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Subject: Re: [PATCH v6 4/6] drm: bridge: add support for Cadence MHDP DPI/DP
 bridge
To:     Damian Kos <dkos@cadence.com>, David Airlie <airlied@linux.ie>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Archit Taneja <architt@codeaurora.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Gustavo Padovan <gustavo@padovan.org>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Sean Paul <sean@poorly.run>, Sandy Huang <hjc@rock-chips.com>,
        =?UTF-8?Q?Heiko_St=c3=bcbner?= <heiko@sntech.de>,
        Quentin Schulz <quentin.schulz@free-electrons.com>,
        Piotr Sroka <piotrs@cadence.com>,
        dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org
Cc:     rafalc@cadence.com, quentin.schulz@bootlin.com, jbergsagel@ti.com
From:   Andrzej Hajda <a.hajda@samsung.com>
Message-ID: <9b3685ab-c2ce-04b5-b044-a536137eee15@samsung.com>
Date:   Mon, 5 Nov 2018 14:10:57 +0100
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On 08.10.2018 23:42, Damian Kos wrote:
> From: Quentin Schulz <quentin.schulz@free-electrons.com>
>
> This adds basic support for Cadence MHDP DPI to DP bridge.
>
> Basically, it takes a DPI stream as input and output it encoded in DP
> format. It's missing proper HPD, HDCP and currently supports only
> SST mode.
>
> Changes made in the low level driver (cdn-dp-reg.*):
> - moved it to from drivers/gpu/drm/rockchip to
>   drivers/gpu/drm/bridge/cdns-mhdp-common.c and
>   include/drm/bridge/cdns-mhdp-common.h
> - functions for sending/receiving commands are now public
> - added functions for reading registers and link training
>   adjustment
>
> Changes made in RK's driver (cdn-dp-core.*):
> - Moved audio_info and audio_pdev fields from cdn_dp_device to
>   cdns_mhdp_device structure.
>
> Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
> Signed-off-by: Damian Kos <dkos@cadence.com>
> ---
>  drivers/gpu/drm/bridge/Kconfig                |    9 +
>  drivers/gpu/drm/bridge/Makefile               |    3 +
>  .../cdns-mhdp-common.c}                       |  136 +-
>  drivers/gpu/drm/bridge/cdns-mhdp.c            | 1304 +++++++++++++++++
>  drivers/gpu/drm/rockchip/Kconfig              |    4 +-
>  drivers/gpu/drm/rockchip/Makefile             |    2 +-
>  drivers/gpu/drm/rockchip/cdn-dp-core.c        |   16 +-
>  drivers/gpu/drm/rockchip/cdn-dp-core.h        |    5 +-
>  .../drm/bridge/cdns-mhdp-common.h             |   21 +-
>  9 files changed, 1480 insertions(+), 20 deletions(-)
>  rename drivers/gpu/drm/{rockchip/cdn-dp-reg.c => bridge/cdns-mhdp-common.c} (87%)
>  create mode 100644 drivers/gpu/drm/bridge/cdns-mhdp.c
>  rename drivers/gpu/drm/rockchip/cdn-dp-reg.h => include/drm/bridge/cdns-mhdp-common.h (95%)
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 9eeb8ef0b174..90a4810a8c96 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -35,6 +35,15 @@ config DRM_CDNS_DSI
>  	  Support Cadence DPI to DSI bridge. This is an internal
>  	  bridge and is meant to be directly embedded in a SoC.
>  
> +config DRM_CDNS_MHDP
> +	tristate "Cadence DPI/DP bridge"
> +	select DRM_KMS_HELPER
> +	select DRM_PANEL_BRIDGE
> +	depends on OF
> +	help
> +	  Support Cadence DPI to DP bridge. This is an internal
> +	  bridge and is meant to be directly embedded in a SoC.
> +
>  config DRM_DUMB_VGA_DAC
>  	tristate "Dumb VGA DAC Bridge support"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 4934fcf5a6f8..e802fdb85750 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -16,4 +16,7 @@ obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> +obj-$(CONFIG_DRM_CDNS_MHDP) += mhdp8546.o


Alphabetic order?


>  obj-y += synopsys/
> +
> +mhdp8546-objs := cdns-mhdp-common.o cdns-mhdp.o
> diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.c b/drivers/gpu/drm/bridge/cdns-mhdp-common.c
> similarity index 87%
> rename from drivers/gpu/drm/rockchip/cdn-dp-reg.c
> rename to drivers/gpu/drm/bridge/cdns-mhdp-common.c
> index c1a76e6fff88..fda1bee7adb5 100644
> --- a/drivers/gpu/drm/rockchip/cdn-dp-reg.c
> +++ b/drivers/gpu/drm/bridge/cdns-mhdp-common.c
> @@ -19,8 +19,9 @@
>  #include <linux/iopoll.h>
>  #include <linux/reset.h>
>  
> -#include "cdn-dp-core.h"
> -#include "cdn-dp-reg.h"
> +#include <drm/drm_print.h>
> +#include <drm/drm_modes.h>
> +#include <drm/bridge/cdns-mhdp-common.h>
>  
>  #define CDNS_DP_SPDIF_CLK		200000000
>  #define FW_ALIVE_TIMEOUT_US		1000000
> @@ -33,6 +34,7 @@ void cdns_mhdp_set_fw_clk(struct cdns_mhdp_device *mhdp, unsigned long clk)
>  {
>  	writel(clk / 1000000, mhdp->regs + SW_CLK_H);
>  }
> +EXPORT_SYMBOL(cdns_mhdp_set_fw_clk);
>  
>  void cdns_mhdp_clock_reset(struct cdns_mhdp_device *mhdp)
>  {
> @@ -82,6 +84,7 @@ void cdns_mhdp_clock_reset(struct cdns_mhdp_device *mhdp)
>  	/* enable Mailbox and PIF interrupt */
>  	writel(0, mhdp->regs + APB_INT_MASK);
>  }
> +EXPORT_SYMBOL(cdns_mhdp_clock_reset);
>  
>  static int cdns_mhdp_mailbox_read(struct cdns_mhdp_device *mhdp)
>  {
> @@ -189,7 +192,56 @@ static int cdns_mhdp_mailbox_send(struct cdns_mhdp_device *mhdp, u8 module_id,
>  	return 0;
>  }
>  
> -static int cdns_mhdp_reg_write(struct cdns_mhdp_device *mhdp, u16 addr, u32 val)
> +int cdns_mhdp_reg_read(struct cdns_mhdp_device *mhdp, u32 addr, u32 *value)
> +{
> +	u8 msg[4], resp[8];
> +	int ret;
> +
> +	if (addr == 0) {
> +		ret = -EINVAL;
> +		goto err_reg_read;
> +	}
> +
> +	msg[0] = (u8)(addr >> 24);
> +	msg[1] = (u8)(addr >> 16);
> +	msg[2] = (u8)(addr >> 8);
> +	msg[3] = (u8)addr;


addr is u16, so  addr >> 16 is always 0, the core question what type of
addr we should use?

To avoid byte shifts you can use put_unaligned_le32 - little more generic.


> +
> +	ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_GENERAL,
> +				     GENERAL_REGISTER_READ,
> +				     sizeof(msg), msg);
> +	if (ret)
> +		goto err_reg_read;
> +
> +	ret = cdns_mhdp_mailbox_validate_receive(mhdp, MB_MODULE_ID_GENERAL,
> +						 GENERAL_REGISTER_READ,
> +						 sizeof(resp));
> +	if (ret)
> +		goto err_reg_read;
> +
> +	ret = cdns_mhdp_mailbox_read_receive(mhdp, resp, sizeof(resp));
> +	if (ret)
> +		goto err_reg_read;
> +
> +	/* Returned address value should be the same as requested */
> +	if (memcmp(msg, resp, sizeof(msg))) {
> +		ret = -EINVAL;
> +		goto err_reg_read;
> +	}
> +
> +	*value = (resp[4] << 24) | (resp[5] << 16) | (resp[6] << 8) | resp[7];


*value = get_unaligned_be32(resp + 4);

and it can be put after if clause below.

> +
> +err_reg_read:
> +	if (ret) {
> +		DRM_DEV_ERROR(mhdp->dev, "Failed to read register.\n");
> +		*value = 0;
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(cdns_mhdp_reg_read);
> +
> +int cdns_mhdp_reg_write(struct cdns_mhdp_device *mhdp, u16 addr, u32 val)
>  {
>  	u8 msg[6];
>  
> @@ -202,8 +254,9 @@ static int cdns_mhdp_reg_write(struct cdns_mhdp_device *mhdp, u16 addr, u32 val)
>  	return cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX,
>  				      DPTX_WRITE_REGISTER, sizeof(msg), msg);
>  }
> +EXPORT_SYMBOL(cdns_mhdp_reg_write);
>  
> -static int cdns_mhdp_reg_write_bit(struct cdns_mhdp_device *mhdp, u16 addr,
> +int cdns_mhdp_reg_write_bit(struct cdns_mhdp_device *mhdp, u16 addr,
>  				   u8 start_bit, u8 bits_no, u32 val)
>  {
>  	u8 field[8];
> @@ -220,6 +273,7 @@ static int cdns_mhdp_reg_write_bit(struct cdns_mhdp_device *mhdp, u16 addr,
>  	return cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX,
>  				      DPTX_WRITE_FIELD, sizeof(field), field);
>  }
> +EXPORT_SYMBOL(cdns_mhdp_reg_write_bit);
>  
>  int cdns_mhdp_dpcd_read(struct cdns_mhdp_device *mhdp,
>  			u32 addr, u8 *data, u16 len)
> @@ -252,6 +306,7 @@ int cdns_mhdp_dpcd_read(struct cdns_mhdp_device *mhdp,
>  err_dpcd_read:
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_dpcd_read);
>  
>  int cdns_mhdp_dpcd_write(struct cdns_mhdp_device *mhdp, u32 addr, u8 value)
>  {
> @@ -286,6 +341,7 @@ int cdns_mhdp_dpcd_write(struct cdns_mhdp_device *mhdp, u32 addr, u8 value)
>  		DRM_DEV_ERROR(mhdp->dev, "dpcd write failed: %d\n", ret);
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_dpcd_write);
>  
>  int cdns_mhdp_load_firmware(struct cdns_mhdp_device *mhdp, const u32 *i_mem,
>  			    u32 i_size, const u32 *d_mem, u32 d_size)
> @@ -328,6 +384,7 @@ int cdns_mhdp_load_firmware(struct cdns_mhdp_device *mhdp, const u32 *i_mem,
>  
>  	return 0;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_load_firmware);
>  
>  int cdns_mhdp_set_firmware_active(struct cdns_mhdp_device *mhdp, bool enable)
>  {
> @@ -362,6 +419,7 @@ int cdns_mhdp_set_firmware_active(struct cdns_mhdp_device *mhdp, bool enable)
>  		DRM_DEV_ERROR(mhdp->dev, "set firmware active failed\n");
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_set_firmware_active);
>  
>  int cdns_mhdp_set_host_cap(struct cdns_mhdp_device *mhdp, u8 lanes, bool flip)
>  {
> @@ -391,6 +449,7 @@ int cdns_mhdp_set_host_cap(struct cdns_mhdp_device *mhdp, u8 lanes, bool flip)
>  		DRM_DEV_ERROR(mhdp->dev, "set host cap failed: %d\n", ret);
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_set_host_cap);
>  
>  int cdns_mhdp_event_config(struct cdns_mhdp_device *mhdp)
>  {
> @@ -408,11 +467,13 @@ int cdns_mhdp_event_config(struct cdns_mhdp_device *mhdp)
>  
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_event_config);
>  
>  u32 cdns_mhdp_get_event(struct cdns_mhdp_device *mhdp)
>  {
>  	return readl(mhdp->regs + SW_EVENTS0);
>  }
> +EXPORT_SYMBOL(cdns_mhdp_get_event);
>  
>  int cdns_mhdp_get_hpd_status(struct cdns_mhdp_device *mhdp)
>  {
> @@ -440,6 +501,7 @@ int cdns_mhdp_get_hpd_status(struct cdns_mhdp_device *mhdp)
>  	DRM_DEV_ERROR(mhdp->dev, "get hpd status failed: %d\n", ret);
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_get_hpd_status);
>  
>  int cdns_mhdp_get_edid_block(void *data, u8 *edid,
>  			  unsigned int block, size_t length)
> @@ -482,6 +544,7 @@ int cdns_mhdp_get_edid_block(void *data, u8 *edid,
>  
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_get_edid_block);
>  
>  static int cdns_mhdp_training_start(struct cdns_mhdp_device *mhdp)
>  {
> @@ -580,6 +643,7 @@ int cdns_mhdp_train_link(struct cdns_mhdp_device *mhdp)
>  			  mhdp->link.num_lanes);
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_train_link);
>  
>  int cdns_mhdp_set_video_status(struct cdns_mhdp_device *mhdp, int active)
>  {
> @@ -595,6 +659,7 @@ int cdns_mhdp_set_video_status(struct cdns_mhdp_device *mhdp, int active)
>  
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_set_video_status);
>  
>  static int cdns_mhdp_get_msa_misc(struct video_info *video,
>  				  struct drm_display_mode *mode)
> @@ -797,6 +862,7 @@ int cdns_mhdp_config_video(struct cdns_mhdp_device *mhdp)
>  		DRM_DEV_ERROR(mhdp->dev, "config video failed: %d\n", ret);
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_config_video);
>  
>  int cdns_mhdp_audio_stop(struct cdns_mhdp_device *mhdp,
>  			 struct audio_info *audio)
> @@ -831,6 +897,7 @@ int cdns_mhdp_audio_stop(struct cdns_mhdp_device *mhdp,
>  
>  	return 0;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_audio_stop);
>  
>  int cdns_mhdp_audio_mute(struct cdns_mhdp_device *mhdp, bool enable)
>  {
> @@ -842,6 +909,7 @@ int cdns_mhdp_audio_mute(struct cdns_mhdp_device *mhdp, bool enable)
>  
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_audio_mute);
>  
>  static void cdns_mhdp_audio_config_i2s(struct cdns_mhdp_device *mhdp,
>  				       struct audio_info *audio)
> @@ -977,3 +1045,63 @@ int cdns_mhdp_audio_config(struct cdns_mhdp_device *mhdp,
>  		DRM_DEV_ERROR(mhdp->dev, "audio config failed: %d\n", ret);
>  	return ret;
>  }
> +EXPORT_SYMBOL(cdns_mhdp_audio_config);
> +
> +int cdns_mhdp_adjust_lt(struct cdns_mhdp_device *mhdp,
> +			u8 nlanes, u16 udelay, u8 *lanes_data, u8 *dpcd)
> +{
> +	u8 payload[7];
> +	u8 hdr[5]; /* For DPCD read response header */
> +	u32 addr;
> +	u8 const nregs = 6; /* Registers 0x202-0x207 */
> +	int ret;
> +
> +	if (nlanes != 4 && nlanes != 2 && nlanes != 1) {
> +		DRM_DEV_ERROR(mhdp->dev, "invalid number of lanes: %d\n",
> +			      nlanes);
> +		ret = -EINVAL;
> +		goto err_adjust_lt;
> +	}
> +
> +	payload[0] = nlanes;
> +	payload[1] = (u8)(udelay >> 8);
> +	payload[2] = (u8)udelay;
> +
> +	payload[3] = lanes_data[0];
> +	if (nlanes > 1)
> +		payload[4] = lanes_data[1];
> +	if (nlanes > 2) {
> +		payload[5] = lanes_data[2];
> +		payload[6] = lanes_data[3];
> +	}


    memcpy(payload+3, lanes_data, nlanes); ?


> +
> +	ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX,
> +				     DPTX_ADJUST_LT,
> +				     sizeof(payload), payload);
> +	if (ret)
> +		goto err_adjust_lt;
> +
> +	/* Yes, read the DPCD read command response */
> +	ret = cdns_mhdp_mailbox_validate_receive(mhdp, MB_MODULE_ID_DP_TX,
> +						 DPTX_READ_DPCD,
> +						 sizeof(hdr) + nregs);
> +	if (ret)
> +		goto err_adjust_lt;
> +
> +	ret = cdns_mhdp_mailbox_read_receive(mhdp, hdr, sizeof(hdr));
> +	if (ret)
> +		goto err_adjust_lt;
> +
> +	addr = (hdr[2] << 24) | (hdr[3] << 8) | hdr[4];


again get_unaligned_*


> +	if (addr != DP_LANE0_1_STATUS)
> +		goto err_adjust_lt;
> +
> +	ret = cdns_mhdp_mailbox_read_receive(mhdp, dpcd, nregs);
> +
> +err_adjust_lt:
> +	if (ret)
> +		DRM_DEV_ERROR(mhdp->dev, "Failed to adjust Link Training.\n");
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(cdns_mhdp_adjust_lt);


Lot of exports here, do we really need them all?


> diff --git a/drivers/gpu/drm/bridge/cdns-mhdp.c b/drivers/gpu/drm/bridge/cdns-mhdp.c
> new file mode 100644
> index 000000000000..a3bbc0e809a5
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/cdns-mhdp.c
> @@ -0,0 +1,1304 @@
> +// SPDX-License-Identifier: GPL v2
> +/*
> + * Cadence MHDP DP bridge driver.
> + *
> + * Copyright: 2018 Cadence Design Systems, Inc.
> + *
> + * Author: Quentin Schulz <quentin.schulz@free-electrons.com>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/firmware.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_connector.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_dp_helper.h>
> +#include <drm/drm_modeset_helper_vtables.h>
> +#include <drm/bridge/cdns-mhdp-common.h>
> +
> +#include <sound/hdmi-codec.h>
> +
> +
> +#define DEBUG_MSG
> +
> +#define FW_NAME					"cadence/mhdp8546.bin"
> +
> +#define CDNS_APB_CFG				0x00000
> +#define CDNS_APB_CTRL				(CDNS_APB_CFG + 0x00)
> +#define CDNS_MAILBOX_FULL			(CDNS_APB_CFG + 0x08)
> +#define CDNS_MAILBOX_EMPTY			(CDNS_APB_CFG + 0x0c)
> +#define CDNS_MAILBOX_TX_DATA			(CDNS_APB_CFG + 0x10)
> +#define CDNS_MAILBOX_RX_DATA			(CDNS_APB_CFG + 0x14)
> +#define CDNS_KEEP_ALIVE				(CDNS_APB_CFG + 0x18)
> +#define CDNS_KEEP_ALIVE_MASK			GENMASK(7, 0)
> +
> +#define CDNS_SW_CLK_L				(CDNS_APB_CFG + 0x3c)
> +#define CDNS_SW_CLK_H				(CDNS_APB_CFG + 0x40)
> +#define CDNS_SW_EVENT0				(CDNS_APB_CFG + 0x44)
> +#define CDNS_DPTX_HPD				BIT(0)
> +
> +#define CDNS_SW_EVENT1				(CDNS_APB_CFG + 0x48)
> +#define CDNS_SW_EVENT2				(CDNS_APB_CFG + 0x4c)
> +#define CDNS_SW_EVENT3				(CDNS_APB_CFG + 0x50)
> +
> +#define CDNS_DPTX_CAR				(CDNS_APB_CFG + 0x904)
> +#define CDNS_VIF_CLK_EN				BIT(0)
> +#define CDNS_VIF_CLK_RSTN			BIT(1)
> +
> +#define CDNS_SOURCE_VIDEO_INTERFACE		0x00b00
> +#define CDNS_BND_HSYNC2VSYNC			(CDNS_SOURCE_VIDEO_INTERFACE + \
> +						 0x00)
> +#define CDNS_IP_DTCT_WIN			GENMASK(11, 0)
> +#define CDNS_IP_DET_INTERLACE_FORMAT		BIT(12)
> +#define CDNS_IP_BYPASS_V_INTERFACE		BIT(13)
> +
> +#define CDNS_HSYNC2VSYNC_POL_CTRL		(CDNS_SOURCE_VIDEO_INTERFACE + \
> +						 0x10)
> +#define CDNS_H2V_HSYNC_POL_ACTIVE_LOW		BIT(1)
> +#define CDNS_H2V_VSYNC_POL_ACTIVE_LOW		BIT(2)
> +
> +#define CDNS_DPTX_PHY_CONFIG			0x02000
> +#define CDNS_PHY_TRAINING_EN			BIT(0)
> +#define CDNS_PHY_TRAINING_TYPE(x)		(((x) & GENMASK(3, 0)) << 1)
> +#define CDNS_PHY_SCRAMBLER_BYPASS		BIT(5)
> +#define CDNS_PHY_ENCODER_BYPASS			BIT(6)
> +#define CDNS_PHY_SKEW_BYPASS			BIT(7)
> +#define CDNS_PHY_TRAINING_AUTO			BIT(8)
> +#define CDNS_PHY_LANE0_SKEW(x)			(((x) & GENMASK(2, 0)) << 9)
> +#define CDNS_PHY_LANE1_SKEW(x)			(((x) & GENMASK(2, 0)) << 12)
> +#define CDNS_PHY_LANE2_SKEW(x)			(((x) & GENMASK(2, 0)) << 15)
> +#define CDNS_PHY_LANE3_SKEW(x)			(((x) & GENMASK(2, 0)) << 18)
> +#define CDNS_PHY_COMMON_CONFIG			(CDNS_PHY_LANE1_SKEW(1) | \
> +						CDNS_PHY_LANE2_SKEW(2) |  \
> +						CDNS_PHY_LANE3_SKEW(3))
> +#define CDNS_PHY_10BIT_EN			BIT(21)
> +
> +#define CDNS_DPTX_FRAMER			0x02200
> +#define CDNS_DP_FRAMER_GLOBAL_CONFIG		(CDNS_DPTX_FRAMER + 0x00)
> +#define CDNS_DP_NUM_LANES(x)			(x - 1)
> +#define CDNS_DP_FRAMER_EN			BIT(3)
> +#define CDNS_DP_RATE_GOVERNOR_EN		BIT(4)
> +#define CDNS_DP_NO_VIDEO_MODE			BIT(5)
> +#define CDNS_DP_DISABLE_PHY_RST			BIT(6)
> +#define CDNS_DP_WR_FAILING_EDGE_VSYNC		BIT(7)
> +
> +#define CDNS_DP_SW_RESET			(CDNS_DPTX_FRAMER + 0x04)
> +#define CDNS_DP_FRAMER_TU			(CDNS_DPTX_FRAMER + 0x08)
> +#define CDNS_DP_FRAMER_TU_SIZE(x)		(((x) & GENMASK(6, 0)) << 8)
> +#define CDNS_DP_FRAMER_TU_VS(x)			((x) & GENMASK(5, 0))
> +#define CDNS_DP_FRAMER_TU_CNT_RST_EN		BIT(15)
> +
> +#define CDNS_DPTX_STREAM			0x03000
> +#define CDNS_DP_MSA_HORIZONTAL_0		(CDNS_DPTX_STREAM + 0x00)
> +#define CDNS_DP_MSAH0_H_TOTAL(x)		(x)
> +#define CDNS_DP_MSAH0_HSYNC_START(x)		((x) << 16)
> +
> +#define CDNS_DP_MSA_HORIZONTAL_1		(CDNS_DPTX_STREAM + 0x04)
> +#define CDNS_DP_MSAH1_HSYNC_WIDTH(x)		(x)
> +#define CDNS_DP_MSAH1_HSYNC_POL_LOW		BIT(15)
> +#define CDNS_DP_MSAH1_HDISP_WIDTH(x)		((x) << 16)
> +
> +#define CDNS_DP_MSA_VERTICAL_0			(CDNS_DPTX_STREAM + 0x08)
> +#define CDNS_DP_MSAV0_V_TOTAL(x)		(x)
> +#define CDNS_DP_MSAV0_VSYNC_START(x)		((x) << 16)
> +
> +#define CDNS_DP_MSA_VERTICAL_1			(CDNS_DPTX_STREAM + 0x0c)
> +#define CDNS_DP_MSAV1_VSYNC_WIDTH(x)		(x)
> +#define CDNS_DP_MSAV1_VSYNC_POL_LOW		BIT(15)
> +#define CDNS_DP_MSAV1_VDISP_WIDTH(x)		((x) << 16)
> +
> +#define CDNS_DP_MSA_MISC			(CDNS_DPTX_STREAM + 0x10)
> +#define CDNS_DP_STREAM_CONFIG			(CDNS_DPTX_STREAM + 0x14)
> +#define CDNS_DP_RATE_GOVERNOR_STATUS		(CDNS_DPTX_STREAM + 0x2c)
> +#define CDNS_DP_RG_TU_VS_DIFF(x)		((x) << 8)
> +
> +#define CDNS_DP_HORIZONTAL			(CDNS_DPTX_STREAM + 0x30)
> +#define CDNS_DP_H_HSYNC_WIDTH(x)		(x)
> +#define CDNS_DP_H_H_TOTAL(x)			((x) << 16)
> +
> +#define CDNS_DP_VERTICAL_0			(CDNS_DPTX_STREAM + 0x34)
> +#define CDNS_DP_V0_VHEIGHT(x)			(x)
> +#define CDNS_DP_V0_VSTART(x)			((x) << 16)
> +
> +#define CDNS_DP_VERTICAL_1			(CDNS_DPTX_STREAM + 0x38)
> +#define CDNS_DP_V1_VTOTAL(x)			(x)
> +#define CDNS_DP_V1_VTOTAL_EVEN			BIT(16)
> +
> +#define CDNS_DP_FRAMER_PXL_REPR			(CDNS_DPTX_STREAM + 0x4c)
> +#define CDNS_DP_FRAMER_6_BPC			BIT(0)
> +#define CDNS_DP_FRAMER_8_BPC			BIT(1)
> +#define CDNS_DP_FRAMER_10_BPC			BIT(2)
> +#define CDNS_DP_FRAMER_12_BPC			BIT(3)
> +#define CDNS_DP_FRAMER_16_BPC			BIT(4)
> +#define CDNS_DP_FRAMER_PXL_FORMAT		0x8
> +#define CDNS_DP_FRAMER_RGB			BIT(0)
> +#define CDNS_DP_FRAMER_YCBCR444			BIT(1)
> +#define CDNS_DP_FRAMER_YCBCR422			BIT(2)
> +#define CDNS_DP_FRAMER_YCBCR420			BIT(3)
> +#define CDNS_DP_FRAMER_Y_ONLY			BIT(4)
> +
> +#define CDNS_DP_FRAMER_SP			(CDNS_DPTX_STREAM + 0x10)
> +#define CDNS_DP_FRAMER_VSYNC_POL_LOW		BIT(0)
> +#define CDNS_DP_FRAMER_HSYNC_POL_LOW		BIT(1)
> +#define CDNS_DP_FRAMER_INTERLACE		BIT(2)
> +
> +#define CDNS_DP_LINE_THRESH			(CDNS_DPTX_STREAM + 0x64)
> +#define CDNS_DP_VB_ID				(CDNS_DPTX_STREAM + 0x68)
> +#define CDNS_DP_VB_ID_INTERLACED		BIT(2)
> +
> +#define CDNS_DP_FRONT_BACK_PORCH		(CDNS_DPTX_STREAM + 0x78)
> +#define CDNS_DP_BACK_PORCH(x)			(x)
> +#define CDNS_DP_FRONT_PORCH(x)			((x) << 16)
> +
> +#define CDNS_DP_BYTE_COUNT			(CDNS_DPTX_STREAM + 0x7c)
> +
> +#define CDNS_DPTX_GLOBAL			0x02300
> +#define CDNS_DP_LANE_EN				(CDNS_DPTX_GLOBAL + 0x00)
> +#define CDNS_DP_LANE_EN_LANES(x)		GENMASK(x - 1, 0)
> +#define CDNS_DP_ENHNCD				(CDNS_DPTX_GLOBAL + 0x04)
> +
> +#define CDNS_MHDP_IMEM				0x10000
> +#define CDNS_MHDP_DMEM				0x20000
> +
> +#define CDNS_DP_TRAINING_PATTERN_4		0x7
> +
> +/* 3min delay because of EDID mb being VERY slow */
> +/* FIXME: should be >615000 when upstreaming */
> +#define CDNS_TIMEOUT_MAILBOX			(1000 * 1000 * 60 * 3)
> +
> +/* FIXME: Should be 2000 */
> +#define CDNS_KEEP_ALIVE_TIMEOUT			40000
> +#define CDNS_SW_EVENT0_TIMEOUT			40000
> +
> +static const struct of_device_id mhdp_ids[] = {
> +	{ .compatible = "cdns,mhdp8546", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, mhdp_ids);
> +
> +#define CDNS_LANE_1				BIT(0)
> +#define CDNS_LANE_2				BIT(1)
> +#define CDNS_LANE_4				BIT(2)
> +#define CDNS_SSC				BIT(3)
> +#define CDNS_SCRAMBLER				BIT(4)
> +
> +#define CDNS_VOLT_SWING(x)			((x) & GENMASK(1, 0))
> +#define CDNS_FORCE_VOLT_SWING			BIT(2)
> +
> +#define CDNS_PRE_EMPHASIS(x)			((x) & GENMASK(1, 0))
> +#define CDNS_FORCE_PRE_EMPHASIS			BIT(2)
> +
> +#define CDNS_SUPPORT_TPS(x)			BIT((x) - 1)
> +
> +#define CDNS_FAST_LINK_TRAINING			BIT(0)
> +
> +#define CDNS_LANE_MAPPING_TYPE_C_LANE_0(x)	((x) & GENMASK(1, 0))
> +#define CDNS_LANE_MAPPING_TYPE_C_LANE_1(x)	((x) & GENMASK(3, 2))
> +#define CDNS_LANE_MAPPING_TYPE_C_LANE_2(x)	((x) & GENMASK(5, 4))
> +#define CDNS_LANE_MAPPING_TYPE_C_LANE_3(x)	((x) & GENMASK(7, 6))
> +#define CDNS_LANE_MAPPING_NORMAL		0xe4
> +#define CDNS_LANE_MAPPING_FLIPPED		0x1b
> +
> +#define CDNS_DP_MAX_NUM_LANES			4
> +#define CDNS_DP_TEST_VSC_SDP			(1 << 6) /* 1.3+ */
> +#define CDNS_DP_TEST_COLOR_FORMAT_RAW_Y_ONLY	(1 << 7)
> +
> +static inline struct cdns_mhdp_device *connector_to_mhdp(
> +	struct drm_connector *conn)
> +{
> +	return container_of(conn, struct cdns_mhdp_device, connector);
> +}
> +
> +static inline struct cdns_mhdp_device *bridge_to_mhdp(
> +	struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct cdns_mhdp_device, bridge);
> +}
> +
> +static unsigned int max_link_rate(struct cdns_mhdp_host host,
> +				  struct cdns_mhdp_sink sink)
> +{
> +	return min(host.link_rate, sink.link_rate);
> +}
> +
> +static u8 eq_training_pattern_supported(struct cdns_mhdp_host host,
> +					struct cdns_mhdp_sink sink)
> +{
> +	return fls(host.pattern_supp & sink.pattern_supp);
> +}
> +
> +static ssize_t mhdp_transfer(struct drm_dp_aux *aux,
> +			     struct drm_dp_aux_msg *msg)
> +{
> +	struct cdns_mhdp_device *mhdp = dev_get_drvdata(aux->dev);
> +	int ret;
> +
> +	if (msg->request != DP_AUX_NATIVE_WRITE &&
> +	    msg->request != DP_AUX_NATIVE_READ)
> +		return -ENOTSUPP;
> +
> +	if (msg->request == DP_AUX_NATIVE_WRITE) {
> +		int i;
> +
> +		for (i = 0; i < msg->size; ++i) {
> +			ret = cdns_mhdp_dpcd_write(mhdp,
> +						   msg->address + i,
> +						   *((u8 *)msg->buffer + i));

Maybe alias would be more readable:

const u8 *buf = msg->buffer;

...

ret = cdns_mhdp_dpcd_write(mhdp, msg->address + i, buf[i]);

> +			if (!ret)
> +				continue;
> +
> +			DRM_DEV_ERROR(mhdp->dev, "Failed to write DPCD\n");
> +
> +			return i;


Here you return number of bytes transfered, and drops error code. It
would be good if somebody confirms it is correctly implemented
aux.transfer error handling. Docs says:

"Upon success, the implementation should return the number of payload
bytes that were transferred, or a negative error-code on failure." - I
would not call this situation success, but maybe I am wrong.


> +		}
> +	} else {
> +		ret = cdns_mhdp_dpcd_read(mhdp, msg->address,
> +					  msg->buffer, msg->size);
> +		if (ret) {
> +			DRM_DEV_ERROR(mhdp->dev, "Failed to read DPCD\n");
> +			return 0;
> +		}
> +	}
> +
> +	return msg->size;
> +}
> +
> +static int cdns_mhdp_get_modes(struct drm_connector *connector)
> +{
> +	struct cdns_mhdp_device *mhdp = connector_to_mhdp(connector);
> +	struct edid *edid;
> +	int num_modes;
> +
> +	edid = drm_do_get_edid(connector, cdns_mhdp_get_edid_block, mhdp);
> +
> +	drm_connector_update_edid_property(connector, edid);
> +
> +	num_modes = drm_add_edid_modes(connector, edid);


Shouldn't edid be released?


> +
> +	return num_modes;
> +}
> +
> +static const struct drm_connector_helper_funcs cdns_mhdp_conn_helper_funcs = {
> +	.get_modes = cdns_mhdp_get_modes,
> +};
> +
> +static enum drm_connector_status cdns_mhdp_detect(struct drm_connector *conn,
> +						  bool force)
> +{
> +	struct cdns_mhdp_device *mhdp = connector_to_mhdp(conn);
> +	enum drm_connector_status status = connector_status_disconnected;
> +	int ret;
> +
> +	ret = cdns_mhdp_get_hpd_status(mhdp);
> +	if (ret > 0)
> +		status = connector_status_connected;
> +	else if (ret < 0)
> +		dev_err(mhdp->dev, "Failed to obtain HPD state\n");
> +
> +	return status;
            if (ret > 0)
                return connector_status_connected;
            if (ret < 0)
                dev_err(mhdp->dev, "Failed to obtain HPD state\n");
            return connector_status_disconnected;
> +}
> +
> +static const struct drm_connector_funcs cdns_mhdp_conn_funcs = {
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +	.reset = drm_atomic_helper_connector_reset,
> +	.destroy = drm_connector_cleanup,
> +	.dpms = drm_helper_connector_dpms,
> +	.detect = cdns_mhdp_detect,
> +};
> +
> +static int cdns_mhdp_attach(struct drm_bridge *bridge)
> +{
> +	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
> +	struct drm_connector *conn = &mhdp->connector;
> +	int ret;
> +
> +	conn->polled = DRM_CONNECTOR_POLL_CONNECT |
> +		DRM_CONNECTOR_POLL_DISCONNECT;
> +
> +	ret = drm_connector_init(bridge->dev, conn, &cdns_mhdp_conn_funcs,
> +				 DRM_MODE_CONNECTOR_DisplayPort);
> +	if (ret) {
> +		dev_err(mhdp->dev, "failed to init connector\n");
> +		return ret;
> +	}
> +
> +	drm_connector_helper_add(conn, &cdns_mhdp_conn_helper_funcs);
> +
> +	ret = drm_connector_attach_encoder(conn, bridge->encoder);
> +	if (ret) {
> +		dev_err(mhdp->dev, "failed to attach connector to encoder\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +enum pixel_format {
> +	PIXEL_FORMAT_RGB = 1,
> +	PIXEL_FORMAT_YCBCR_444 = 2,
> +	PIXEL_FORMAT_YCBCR_422 = 4,
> +	PIXEL_FORMAT_YCBCR_420 = 8,
> +	PIXEL_FORMAT_Y_ONLY = 16,
> +};
> +
> +static void mhdp_link_training_init(struct cdns_mhdp_device *mhdp)
> +{
> +	u32 reg32;
> +
> +	drm_dp_dpcd_writeb(&mhdp->aux, DP_TRAINING_PATTERN_SET,
> +			   DP_TRAINING_PATTERN_DISABLE);
> +
> +	/* Reset PHY configuration */
> +	reg32 = CDNS_PHY_COMMON_CONFIG | CDNS_PHY_TRAINING_TYPE(1);
> +	if (!(mhdp->host.lanes_cnt & CDNS_SCRAMBLER))
> +		reg32 |= CDNS_PHY_SCRAMBLER_BYPASS;
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DPTX_PHY_CONFIG, reg32);
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_ENHNCD,
> +			    mhdp->sink.enhanced & mhdp->host.enhanced);
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_LANE_EN,
> +			    CDNS_DP_LANE_EN_LANES(mhdp->link.num_lanes));
> +
> +	drm_dp_link_configure(&mhdp->aux, &mhdp->link);
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DPTX_PHY_CONFIG,
> +			    CDNS_PHY_COMMON_CONFIG |
> +			    CDNS_PHY_TRAINING_EN |
> +			    CDNS_PHY_TRAINING_TYPE(1) |
> +			    CDNS_PHY_SCRAMBLER_BYPASS);
> +
> +	drm_dp_dpcd_writeb(&mhdp->aux, DP_TRAINING_PATTERN_SET,
> +			   DP_TRAINING_PATTERN_1 | DP_LINK_SCRAMBLING_DISABLE);
> +}
> +
> +static void mhdp_get_adjust_train(struct cdns_mhdp_device *mhdp,
> +				  u8 link_status[DP_LINK_STATUS_SIZE],
> +				  u8 lanes_data[CDNS_DP_MAX_NUM_LANES])
> +{
> +	unsigned int i;
> +	u8 adjust, max_pre_emphasis, max_volt_swing;
> +
> +	max_pre_emphasis = CDNS_PRE_EMPHASIS(mhdp->host.pre_emphasis)
> +		<< DP_TRAIN_PRE_EMPHASIS_SHIFT;
> +	max_volt_swing = CDNS_VOLT_SWING(mhdp->host.volt_swing);
> +
> +	for (i = 0; i < mhdp->link.num_lanes; i++) {
> +		adjust = drm_dp_get_adjust_request_voltage(link_status, i);
> +		lanes_data[i] = min_t(u8, adjust, max_volt_swing);
> +		if (lanes_data[i] != adjust)
> +			lanes_data[i] |= DP_TRAIN_MAX_SWING_REACHED;
> +
> +		adjust = drm_dp_get_adjust_request_pre_emphasis(link_status, i);
> +		lanes_data[i] |= min_t(u8, adjust, max_pre_emphasis);
> +		if ((lanes_data[i] >> DP_TRAIN_PRE_EMPHASIS_SHIFT) != adjust)
> +			lanes_data[i] |= DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
> +	}
> +}
> +
> +static void mhdp_set_adjust_request_voltage(
> +	u8 link_status[DP_LINK_STATUS_SIZE], int lane, u8 volt)
> +{
> +	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
> +	int s = ((lane & 1) ?
> +		 DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT :
> +		 DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT);
> +	int idx = i - DP_LANE0_1_STATUS;
> +
> +	link_status[idx] &= ~(DP_ADJUST_VOLTAGE_SWING_LANE0_MASK << s);
> +	link_status[idx] |= volt << s;
> +}
> +
> +static void mhdp_set_adjust_request_pre_emphasis(
> +	u8 link_status[DP_LINK_STATUS_SIZE], int lane, u8 pre_emphasis)
> +{
> +	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
> +	int s = ((lane & 1) ?
> +		 DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT :
> +		 DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT);
> +	int idx = i - DP_LANE0_1_STATUS;
> +
> +	link_status[idx] &= ~(DP_ADJUST_PRE_EMPHASIS_LANE0_MASK << s);
> +	link_status[idx] |= pre_emphasis << s;
> +}
> +
> +static void mhdp_adjust_requested_eq(struct cdns_mhdp_device *mhdp,
> +				     u8 link_status[DP_LINK_STATUS_SIZE])
> +{
> +	unsigned int i;
> +	u8 pre, volt, max_pre = CDNS_VOLT_SWING(mhdp->host.volt_swing),
> +	   max_volt = CDNS_PRE_EMPHASIS(mhdp->host.pre_emphasis);
> +
> +	for (i = 0; i < mhdp->link.num_lanes; i++) {
> +		volt = drm_dp_get_adjust_request_voltage(link_status, i);
> +		pre = drm_dp_get_adjust_request_pre_emphasis(link_status, i);
> +		if (volt + pre > 3)
> +			mhdp_set_adjust_request_voltage(link_status, i,
> +							3 - pre);
> +		if (mhdp->host.volt_swing & CDNS_FORCE_VOLT_SWING)
> +			mhdp_set_adjust_request_voltage(link_status, i,
> +							max_volt);
> +		if (mhdp->host.pre_emphasis & CDNS_FORCE_PRE_EMPHASIS)
> +			mhdp_set_adjust_request_pre_emphasis(link_status, i,
> +							     max_pre);
> +	}
> +}
> +
> +static bool mhdp_link_training_channel_eq(struct cdns_mhdp_device *mhdp,
> +					  u8 eq_tps,
> +					  unsigned int training_interval)
> +{
> +	u8 lanes_data[CDNS_DP_MAX_NUM_LANES], fail_counter_short = 0;
> +	u8 dpcd[DP_LINK_STATUS_SIZE];
> +	u32 reg32;
> +
> +	dev_dbg(mhdp->dev, "Link training - Starting EQ phase\n");
> +
> +	/* Enable link training TPS[eq_tps] in PHY */
> +	reg32 = CDNS_PHY_COMMON_CONFIG | CDNS_PHY_TRAINING_EN |
> +		CDNS_PHY_TRAINING_TYPE(eq_tps);
> +	if (eq_tps != 4)
> +		reg32 |= CDNS_PHY_SCRAMBLER_BYPASS;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DPTX_PHY_CONFIG, reg32);
> +
> +	drm_dp_dpcd_writeb(&mhdp->aux, DP_TRAINING_PATTERN_SET,
> +			   (eq_tps != 4) ? eq_tps | DP_LINK_SCRAMBLING_DISABLE :
> +			   CDNS_DP_TRAINING_PATTERN_4);
> +
> +	drm_dp_dpcd_read_link_status(&mhdp->aux, dpcd);
> +
> +	do {
> +		mhdp_get_adjust_train(mhdp, dpcd, lanes_data);
> +
> +		cdns_mhdp_adjust_lt(mhdp, mhdp->link.num_lanes,
> +				    training_interval, lanes_data, dpcd);
> +
> +		if (!drm_dp_clock_recovery_ok(dpcd, mhdp->link.num_lanes))
> +			goto err;
> +
> +		if (drm_dp_channel_eq_ok(dpcd, mhdp->link.num_lanes)) {
> +			dev_dbg(mhdp->dev,
> +				"Link training: EQ phase succeeded\n");
> +			return true;
> +		}
> +
> +		fail_counter_short++;
> +
> +		mhdp_adjust_requested_eq(mhdp, dpcd);
> +	} while (fail_counter_short < 5);
> +
> +err:
> +	dev_dbg(mhdp->dev,
> +		"Link training - EQ phase failed for %d lanes and %d rate\n",
> +		mhdp->link.num_lanes, mhdp->link.rate);
> +
> +	return false;
> +}
> +
> +static void mhdp_adjust_requested_cr(struct cdns_mhdp_device *mhdp,
> +				     u8 link_status[DP_LINK_STATUS_SIZE],
> +				     u8 *req_volt, u8 *req_pre)
> +{
> +	unsigned int i, max_volt = CDNS_VOLT_SWING(mhdp->host.volt_swing),
> +		     max_pre = CDNS_PRE_EMPHASIS(mhdp->host.pre_emphasis);
> +
> +	for (i = 0; i < mhdp->link.num_lanes; i++) {
> +		if (mhdp->host.volt_swing & CDNS_FORCE_VOLT_SWING)
> +			mhdp_set_adjust_request_voltage(link_status, i,
> +							max_volt);
> +		else
> +			mhdp_set_adjust_request_voltage(link_status, i,
> +							req_volt[i]);
> +
> +		if (mhdp->host.pre_emphasis & CDNS_FORCE_PRE_EMPHASIS)
> +			mhdp_set_adjust_request_pre_emphasis(link_status, i,
> +							     max_pre);
> +		else
> +			mhdp_set_adjust_request_pre_emphasis(link_status, i,
> +							     req_pre[i]);
> +	}
> +}
> +
> +static void mhdp_validate_cr(struct cdns_mhdp_device *mhdp, bool *cr_done,
> +			     bool *same_before_adjust, bool *max_swing_reached,
> +			     u8 before_cr[DP_LINK_STATUS_SIZE],
> +			     u8 after_cr[DP_LINK_STATUS_SIZE], u8 *req_volt,
> +			     u8 *req_pre)
> +{
> +	unsigned int i;
> +	u8 tmp, max_volt = CDNS_VOLT_SWING(mhdp->host.volt_swing),
> +	   max_pre = CDNS_PRE_EMPHASIS(mhdp->host.pre_emphasis);
> +	bool same_pre, same_volt;
> +
> +	*same_before_adjust = false;
> +	*max_swing_reached = false;
> +	*cr_done = drm_dp_clock_recovery_ok(after_cr, mhdp->link.num_lanes);
> +
> +	for (i = 0; i < mhdp->link.num_lanes; i++) {
> +		tmp = drm_dp_get_adjust_request_voltage(after_cr, i);
> +		req_volt[i] = min_t(u8, tmp, max_volt);
> +
> +		tmp = drm_dp_get_adjust_request_pre_emphasis(after_cr, i) >>
> +			DP_TRAIN_PRE_EMPHASIS_SHIFT;
> +		req_pre[i] = min_t(u8, tmp, max_pre);
> +
> +		same_pre = (before_cr[i] & DP_TRAIN_PRE_EMPHASIS_MASK) ==
> +			(req_pre[i] << DP_TRAIN_PRE_EMPHASIS_SHIFT);
> +		same_volt = (before_cr[i] & DP_TRAIN_VOLTAGE_SWING_MASK) ==
> +			req_volt[i];
> +		if (same_pre && same_volt)
> +			*same_before_adjust = true;
> +
> +		/* 3.1.5.2 in DP Standard v1.4. Table 3-1 */
> +		if (!*cr_done && req_volt[i] + req_pre[i] >= 3) {
> +			*max_swing_reached = true;
> +			return;
> +		}
> +	}
> +}
> +
> +static bool mhdp_link_training_clock_recovery(struct cdns_mhdp_device *mhdp)
> +{
> +	u8 lanes_data[CDNS_DP_MAX_NUM_LANES], fail_counter_short = 0,
> +	   fail_counter_cr_long = 0;
> +	u8 dpcd[DP_LINK_STATUS_SIZE];
> +	bool cr_done;
> +
> +	dev_dbg(mhdp->dev, "Link training starting CR phase\n");
> +
> +	mhdp_link_training_init(mhdp);
> +
> +	drm_dp_dpcd_read_link_status(&mhdp->aux, dpcd);
> +
> +	do {
> +		u8 requested_adjust_volt_swing[CDNS_DP_MAX_NUM_LANES] = {},
> +		   requested_adjust_pre_emphasis[CDNS_DP_MAX_NUM_LANES] = {};
> +		bool same_before_adjust, max_swing_reached;
> +
> +		mhdp_get_adjust_train(mhdp, dpcd, lanes_data);
> +
> +		cdns_mhdp_adjust_lt(mhdp, mhdp->link.num_lanes, 100,
> +				    lanes_data, dpcd);
> +
> +		mhdp_validate_cr(mhdp, &cr_done, &same_before_adjust,
> +				 &max_swing_reached, lanes_data, dpcd,
> +				 requested_adjust_volt_swing,
> +				 requested_adjust_pre_emphasis);
> +
> +		if (max_swing_reached)
> +			goto err;
> +
> +		if (cr_done) {
> +			dev_dbg(mhdp->dev,
> +				"Link training: CR phase succeeded\n");
> +			return true;
> +		}
> +
> +		/* Not all CR_DONE bits set */
> +		fail_counter_cr_long++;
> +
> +		if (same_before_adjust) {
> +			fail_counter_short++;
> +			continue;
> +		}
> +
> +		fail_counter_short = 0;
> +		/*
> +		 * Voltage swing/pre-emphasis adjust requested
> +		 * during CR phase
> +		 */
> +		mhdp_adjust_requested_cr(mhdp, dpcd,
> +					 requested_adjust_volt_swing,
> +					 requested_adjust_pre_emphasis);
> +	} while (fail_counter_short < 5 && fail_counter_cr_long < 10);
> +
> +err:
> +	dev_dbg(mhdp->dev,
> +		"Link training: CR phase failed for %d lanes and %d rate\n",
> +		mhdp->link.num_lanes, mhdp->link.rate);
> +
> +	return false;
> +}
> +
> +static void lower_link_rate(struct drm_dp_link *link)
> +{
> +	switch (drm_dp_link_rate_to_bw_code(link->rate)) {
> +	case DP_LINK_BW_2_7:
> +		link->rate = drm_dp_bw_code_to_link_rate(DP_LINK_BW_1_62);
> +		break;
> +	case DP_LINK_BW_5_4:
> +		link->rate = drm_dp_bw_code_to_link_rate(DP_LINK_BW_2_7);
> +		break;
> +	case DP_LINK_BW_8_1:
> +		link->rate = drm_dp_bw_code_to_link_rate(DP_LINK_BW_5_4);
> +		break;
> +	}
> +}


Quite subotpimal code conversion from rates to bw_code and then back.

I suspect the link training code across whole drms is waiting for
generic helpers and refactoring.


> +
> +static int mhdp_link_training(struct cdns_mhdp_device *mhdp,
> +			      unsigned int video_mode,
> +			      unsigned int training_interval)
> +{
> +	u32 reg32;
> +	u8 eq_tps = eq_training_pattern_supported(mhdp->host, mhdp->sink);
> +
> +	while (1) {
> +		if (!mhdp_link_training_clock_recovery(mhdp)) {
> +			if (drm_dp_link_rate_to_bw_code(mhdp->link.rate) !=
> +			    DP_LINK_BW_1_62) {
> +				dev_dbg(mhdp->dev,
> +					"Reducing link rate during CR phase\n");
> +				lower_link_rate(&mhdp->link);
> +				drm_dp_link_configure(&mhdp->aux, &mhdp->link);
> +
> +				continue;
> +			} else if (mhdp->link.num_lanes > 1) {
> +				dev_dbg(mhdp->dev,
> +					"Reducing lanes number during CR phase\n");
> +				mhdp->link.num_lanes >>= 1;
> +				mhdp->link.rate = max_link_rate(mhdp->host,
> +								mhdp->sink);
> +				drm_dp_link_configure(&mhdp->aux, &mhdp->link);
> +
> +				continue;
> +			}
> +
> +			dev_dbg(mhdp->dev,
> +				"Link training failed during CR phase\n");
> +			goto err;
> +		}
> +
> +		if (mhdp_link_training_channel_eq(mhdp, eq_tps,
> +						  training_interval))
> +			break;
> +
> +		if (mhdp->link.num_lanes > 1) {
> +			dev_dbg(mhdp->dev,
> +				"Reducing lanes number during EQ phase\n");
> +			mhdp->link.num_lanes >>= 1;
> +			drm_dp_link_configure(&mhdp->aux, &mhdp->link);
> +
> +			continue;
> +		} else if (drm_dp_link_rate_to_bw_code(mhdp->link.rate) !=
> +			   DP_LINK_BW_1_62) {
> +			dev_dbg(mhdp->dev,
> +				"Reducing link rate during EQ phase\n");
> +			lower_link_rate(&mhdp->link);
> +			drm_dp_link_configure(&mhdp->aux, &mhdp->link);
> +
> +			continue;
> +		}
> +
> +		dev_dbg(mhdp->dev, "Link training failed during EQ phase\n");
> +		goto err;
> +	}
> +
> +	dev_dbg(mhdp->dev, "Link training successful\n");
> +
> +	drm_dp_dpcd_writeb(&mhdp->aux, DP_TRAINING_PATTERN_SET,
> +			   (mhdp->host.lanes_cnt & CDNS_SCRAMBLER) ? 0 :
> +			   DP_LINK_SCRAMBLING_DISABLE);
> +
> +	/* SW reset DPTX framer */
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_SW_RESET, 1);
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_SW_RESET, 0);
> +
> +	/* Enable framer */
> +	/* FIXME: update when MST supported, BIT(2) */
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_FRAMER_GLOBAL_CONFIG,
> +			    CDNS_DP_FRAMER_EN |
> +			    CDNS_DP_NUM_LANES(mhdp->link.num_lanes) |
> +			    CDNS_DP_DISABLE_PHY_RST |
> +			    CDNS_DP_WR_FAILING_EDGE_VSYNC |
> +			    (!video_mode ? CDNS_DP_NO_VIDEO_MODE : 0));
> +
> +	/* Reset PHY config */
> +	reg32 = CDNS_PHY_COMMON_CONFIG | CDNS_PHY_TRAINING_TYPE(1);
> +	if (!(mhdp->host.lanes_cnt & CDNS_SCRAMBLER))
> +		reg32 |= CDNS_PHY_SCRAMBLER_BYPASS;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DPTX_PHY_CONFIG, reg32);
> +
> +	return 0;
> +err:
> +	/* Reset PHY config */
> +	reg32 = CDNS_PHY_COMMON_CONFIG | CDNS_PHY_TRAINING_TYPE(1);
> +	if (!(mhdp->host.lanes_cnt & CDNS_SCRAMBLER))
> +		reg32 |= CDNS_PHY_SCRAMBLER_BYPASS;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DPTX_PHY_CONFIG, reg32);
> +
> +	drm_dp_dpcd_writeb(&mhdp->aux, DP_TRAINING_PATTERN_SET,
> +			   DP_TRAINING_PATTERN_DISABLE);
> +
> +	return -EIO;
> +}
> +
> +static void cdns_mhdp_disable(struct drm_bridge *bridge)
> +{
> +	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
> +
> +	cdns_mhdp_set_video_status(mhdp, 0);
> +
> +	drm_dp_link_power_down(&mhdp->aux, &mhdp->link);
> +}
> +
> +static void cdns_mhdp_enable(struct drm_bridge *bridge)
> +{
> +	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
> +	struct drm_display_mode *mode;
> +	struct drm_display_info *disp_info = &mhdp->connector.display_info;
> +	enum pixel_format pxlfmt;
> +	int pxlclock;
> +	unsigned int rate, tu_size = 30, vs, vs_f, bpp, required_bandwidth,
> +		     available_bandwidth, dp_framer_sp = 0, msa_horizontal_1,
> +		     msa_vertical_1, bnd_hsync2vsync, hsync2vsync_pol_ctrl,
> +		     misc0 = 0, misc1 = 0, line_thresh = 0, pxl_repr,
> +		     front_porch, back_porch, msa_h0, msa_v0, hsync, vsync,
> +		     dp_vertical_1, line_thresh1, line_thresh2;
> +	u32 resp;


Number of variables and number of lines in the function suggests it
should be split.


> +
> +	unsigned int size = DP_RECEIVER_CAP_SIZE, dp_framer_global_config,
> +		     video_mode, training_interval_us;
> +	u8 reg0[size], reg8, amp[2];
> +
> +	mode = &bridge->encoder->crtc->state->adjusted_mode;
> +	pxlclock = mode->crtc_clock;
> +
> +	/*
> +	 * Upon power-on reset/device disconnection: [2:0] bits should be 0b001
> +	 * and [7:5] bits 0b000.
> +	 */
> +	drm_dp_dpcd_writeb(&mhdp->aux, DP_SET_POWER, 1);
> +
> +	drm_dp_link_probe(&mhdp->aux, &mhdp->link);
> +
> +	dev_dbg(mhdp->dev, "Set sink device power state via DPCD\n");
> +	drm_dp_link_power_up(&mhdp->aux, &mhdp->link);
> +	/* FIXME (CDNS): do we have to wait for 100ms before going on? */
> +	mdelay(100);
> +
> +	mhdp->sink.link_rate = mhdp->link.rate;
> +	mhdp->sink.lanes_cnt = mhdp->link.num_lanes;
> +	mhdp->sink.enhanced = !!(mhdp->link.capabilities &
> +				 DP_LINK_CAP_ENHANCED_FRAMING);
> +
> +	drm_dp_dpcd_read(&mhdp->aux, DP_DPCD_REV, reg0, size);
> +
> +	mhdp->sink.pattern_supp = CDNS_SUPPORT_TPS(1) | CDNS_SUPPORT_TPS(2);
> +	if (drm_dp_tps3_supported(reg0))
> +		mhdp->sink.pattern_supp |= CDNS_SUPPORT_TPS(3);
> +	if (drm_dp_tps4_supported(reg0))
> +		mhdp->sink.pattern_supp |= CDNS_SUPPORT_TPS(4);
> +
> +	mhdp->sink.fast_link = !!(reg0[DP_MAX_DOWNSPREAD] &
> +				  DP_NO_AUX_HANDSHAKE_LINK_TRAINING);
> +
> +	mhdp->link.rate = max_link_rate(mhdp->host, mhdp->sink);
> +	mhdp->link.num_lanes = min_t(u8, mhdp->sink.lanes_cnt,
> +				     mhdp->host.lanes_cnt & GENMASK(2, 0));
> +
> +	reg8 = reg0[DP_TRAINING_AUX_RD_INTERVAL] &
> +		DP_TRAINING_AUX_RD_MASK;
> +	switch (reg8) {
> +	case 0:
> +		training_interval_us = 400;
> +		break;
> +	case 1:
> +	case 2:
> +	case 3:
> +	case 4:
> +		training_interval_us = 4000 << (reg8 - 1);
> +		break;
> +	default:
> +		dev_err(mhdp->dev,
> +			"wrong training interval returned by DPCD: %d\n", reg8);
> +		return;
> +	}
> +
> +	cdns_mhdp_reg_read(mhdp, CDNS_DP_FRAMER_GLOBAL_CONFIG, &resp);
> +
> +	dp_framer_global_config = be32_to_cpu(resp);
> +
> +	video_mode = !(dp_framer_global_config & CDNS_DP_NO_VIDEO_MODE);
> +
> +	if (dp_framer_global_config & CDNS_DP_FRAMER_EN)
> +		cdns_mhdp_reg_write(mhdp, CDNS_DP_FRAMER_GLOBAL_CONFIG,
> +				    dp_framer_global_config &
> +				    ~CDNS_DP_FRAMER_EN);
> +
> +	/* Spread AMP if required, enable 8b/10b coding */
> +	amp[0] = (mhdp->host.lanes_cnt & CDNS_SSC) ? DP_SPREAD_AMP_0_5 : 0;
> +	amp[1] = DP_SET_ANSI_8B10B;
> +	drm_dp_dpcd_write(&mhdp->aux, DP_DOWNSPREAD_CTRL, amp, 2);
> +
> +	if (mhdp->host.fast_link & mhdp->sink.fast_link) {
> +		/* FIXME: implement fastlink */
> +		dev_dbg(mhdp->dev, "fastlink\n");
> +	} else {
> +		if (mhdp_link_training(mhdp, video_mode,
> +				       training_interval_us)) {
> +			dev_err(mhdp->dev, "Link training failed. Exiting.\n");
> +			return;
> +		}
> +	}
> +
> +	rate = mhdp->link.rate / 1000;
> +
> +	/* FIXME: what about Y_ONLY? how is it handled in the kernel? */
> +	if (disp_info->color_formats & DRM_COLOR_FORMAT_YCRCB444)
> +		pxlfmt = PIXEL_FORMAT_YCBCR_444;
> +	else if (disp_info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
> +		pxlfmt = PIXEL_FORMAT_YCBCR_422;
> +	else if (disp_info->color_formats & DRM_COLOR_FORMAT_YCRCB420)
> +		pxlfmt = PIXEL_FORMAT_YCBCR_420;
> +	else
> +		pxlfmt = PIXEL_FORMAT_RGB;
> +
> +	/* if YCBCR supported and stream not SD, use ITU709 */
> +	/* FIXME: handle ITU version with YCBCR420 when supported */
> +	if ((pxlfmt == PIXEL_FORMAT_YCBCR_444 ||
> +	     pxlfmt == PIXEL_FORMAT_YCBCR_422) && mode->crtc_vdisplay >= 720)
> +		misc0 = DP_YCBCR_COEFFICIENTS_ITU709;
> +
> +	switch (pxlfmt) {
> +	case PIXEL_FORMAT_RGB:
> +		bpp = disp_info->bpc * 3;
> +		pxl_repr = CDNS_DP_FRAMER_RGB << CDNS_DP_FRAMER_PXL_FORMAT;
> +		misc0 |= DP_COLOR_FORMAT_RGB;
> +		break;
> +	case PIXEL_FORMAT_YCBCR_444:
> +		bpp = disp_info->bpc * 3;
> +		pxl_repr = CDNS_DP_FRAMER_YCBCR444 << CDNS_DP_FRAMER_PXL_FORMAT;
> +		misc0 |= DP_COLOR_FORMAT_YCbCr444 | DP_TEST_DYNAMIC_RANGE_CEA;
> +		break;
> +	case PIXEL_FORMAT_YCBCR_422:
> +		bpp = disp_info->bpc * 2;
> +		pxl_repr = CDNS_DP_FRAMER_YCBCR422 << CDNS_DP_FRAMER_PXL_FORMAT;
> +		misc0 |= DP_COLOR_FORMAT_YCbCr422 | DP_TEST_DYNAMIC_RANGE_CEA;
> +		break;
> +	case PIXEL_FORMAT_YCBCR_420:
> +		bpp = disp_info->bpc * 3 / 2;
> +		pxl_repr = CDNS_DP_FRAMER_YCBCR420 << CDNS_DP_FRAMER_PXL_FORMAT;
> +		break;
> +	default:
> +		bpp = disp_info->bpc;
> +		pxl_repr = CDNS_DP_FRAMER_Y_ONLY << CDNS_DP_FRAMER_PXL_FORMAT;
> +	}
> +
> +	switch (disp_info->bpc) {
> +	case 6:
> +		misc0 |= DP_TEST_BIT_DEPTH_6;
> +		pxl_repr |= CDNS_DP_FRAMER_6_BPC;
> +		break;
> +	case 8:
> +		misc0 |= DP_TEST_BIT_DEPTH_8;
> +		pxl_repr |= CDNS_DP_FRAMER_8_BPC;
> +		break;
> +	case 10:
> +		misc0 |= DP_TEST_BIT_DEPTH_10;
> +		pxl_repr |= CDNS_DP_FRAMER_10_BPC;
> +		break;
> +	case 12:
> +		misc0 |= DP_TEST_BIT_DEPTH_12;
> +		pxl_repr |= CDNS_DP_FRAMER_12_BPC;
> +		break;
> +	case 16:
> +		misc0 |= DP_TEST_BIT_DEPTH_16;
> +		pxl_repr |= CDNS_DP_FRAMER_16_BPC;
> +		break;
> +	}
> +
> +	/* find optimal tu_size */
> +	required_bandwidth = pxlclock * bpp / 8;
> +	available_bandwidth = mhdp->link.num_lanes * rate;
> +	do {
> +		tu_size += 2;
> +
> +		vs_f = tu_size * required_bandwidth / available_bandwidth;
> +		vs = vs_f / 1000;
> +		vs_f = vs_f % 1000;
> +		/*
> +		 * FIXME (CDNS): downspreading?
> +		 * It's unused is what I've been told.
> +		 */
> +	} while ((vs == 1 || ((vs_f > 850 || vs_f < 100) && vs_f != 0) ||
> +		  tu_size - vs < 2) && tu_size < 64);
> +
> +	if (vs > 64)
> +		return;
> +
> +	bnd_hsync2vsync = CDNS_IP_BYPASS_V_INTERFACE;
> +	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
> +		bnd_hsync2vsync |= CDNS_IP_DET_INTERLACE_FORMAT;
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_BND_HSYNC2VSYNC, bnd_hsync2vsync);
> +
> +	if (mode->flags & DRM_MODE_FLAG_INTERLACE &&
> +	    mode->flags & DRM_MODE_FLAG_PHSYNC)
> +		hsync2vsync_pol_ctrl = CDNS_H2V_HSYNC_POL_ACTIVE_LOW |
> +			CDNS_H2V_VSYNC_POL_ACTIVE_LOW;
> +	else
> +		hsync2vsync_pol_ctrl = 0;
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_HSYNC2VSYNC_POL_CTRL,
> +			    hsync2vsync_pol_ctrl);
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_FRAMER_TU,
> +			    CDNS_DP_FRAMER_TU_VS(vs) |
> +			    CDNS_DP_FRAMER_TU_SIZE(tu_size) |
> +			    CDNS_DP_FRAMER_TU_CNT_RST_EN);
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_FRAMER_PXL_REPR, pxl_repr);
> +
> +	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
> +		dp_framer_sp |= CDNS_DP_FRAMER_INTERLACE;
> +	if (mode->flags & DRM_MODE_FLAG_NHSYNC)
> +		dp_framer_sp |= CDNS_DP_FRAMER_HSYNC_POL_LOW;
> +	if (mode->flags & DRM_MODE_FLAG_NVSYNC)
> +		dp_framer_sp |= CDNS_DP_FRAMER_VSYNC_POL_LOW;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_FRAMER_SP, dp_framer_sp);
> +
> +	front_porch = mode->crtc_hsync_start - mode->crtc_hdisplay;
> +	back_porch = mode->crtc_htotal - mode->crtc_hsync_end;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_FRONT_BACK_PORCH,
> +			    CDNS_DP_FRONT_PORCH(front_porch) |
> +			    CDNS_DP_BACK_PORCH(back_porch));
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_BYTE_COUNT,
> +			    mode->crtc_hdisplay * bpp / 8);
> +
> +	msa_h0 = mode->crtc_htotal - mode->crtc_hsync_start;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_MSA_HORIZONTAL_0,
> +			    CDNS_DP_MSAH0_H_TOTAL(mode->crtc_htotal) |
> +			    CDNS_DP_MSAH0_HSYNC_START(msa_h0));
> +
> +	hsync = mode->crtc_hsync_end - mode->crtc_hsync_start;
> +	msa_horizontal_1 = CDNS_DP_MSAH1_HSYNC_WIDTH(hsync) |
> +		CDNS_DP_MSAH1_HDISP_WIDTH(mode->crtc_hdisplay);
> +	if (mode->flags & DRM_MODE_FLAG_NHSYNC)
> +		msa_horizontal_1 |= CDNS_DP_MSAH1_HSYNC_POL_LOW;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_MSA_HORIZONTAL_1,
> +			    msa_horizontal_1);
> +
> +	msa_v0 = mode->crtc_vtotal - mode->crtc_vsync_start;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_MSA_VERTICAL_0,
> +			    CDNS_DP_MSAV0_V_TOTAL(mode->crtc_vtotal) |
> +			    CDNS_DP_MSAV0_VSYNC_START(msa_v0));
> +
> +	vsync = mode->crtc_vsync_end - mode->crtc_vsync_start;
> +	msa_vertical_1 = CDNS_DP_MSAV1_VSYNC_WIDTH(vsync) |
> +		CDNS_DP_MSAV1_VDISP_WIDTH(mode->crtc_vdisplay);
> +	if (mode->flags & DRM_MODE_FLAG_NVSYNC)
> +		msa_vertical_1 |= CDNS_DP_MSAV1_VSYNC_POL_LOW;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_MSA_VERTICAL_1, msa_vertical_1);
> +
> +	if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
> +	    mode->crtc_vtotal % 2 == 0)
> +		misc1 = DP_TEST_INTERLACED;
> +	if (pxlfmt == PIXEL_FORMAT_Y_ONLY)
> +		misc1 |= CDNS_DP_TEST_COLOR_FORMAT_RAW_Y_ONLY;
> +	/* FIXME: use VSC SDP for Y420 */
> +	/* FIXME: (CDNS) no code for Y420 in bare metal test */
> +	if (pxlfmt == PIXEL_FORMAT_YCBCR_420)
> +		misc1 = CDNS_DP_TEST_VSC_SDP;
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_MSA_MISC, misc0 | (misc1 << 8));
> +
> +	/* FIXME: to be changed if MST mode */
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_STREAM_CONFIG, 1);
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_HORIZONTAL,
> +			    CDNS_DP_H_HSYNC_WIDTH(hsync) |
> +			    CDNS_DP_H_H_TOTAL(mode->crtc_hdisplay));
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_VERTICAL_0,
> +			    CDNS_DP_V0_VHEIGHT(mode->crtc_vdisplay) |
> +			    CDNS_DP_V0_VSTART(msa_v0));
> +
> +	dp_vertical_1 = CDNS_DP_V1_VTOTAL(mode->crtc_vtotal);
> +	if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
> +	    mode->crtc_vtotal % 2 == 0)
> +		dp_vertical_1 |= CDNS_DP_V1_VTOTAL_EVEN;
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_VERTICAL_1, dp_vertical_1);
> +
> +	cdns_mhdp_reg_write_bit(mhdp, CDNS_DP_VB_ID, 2, 1,
> +				(mode->flags & DRM_MODE_FLAG_INTERLACE) ?
> +				CDNS_DP_VB_ID_INTERLACED : 0);
> +
> +	line_thresh1 = ((vs + 1) << 5) * 8 / bpp;
> +	line_thresh2 = (pxlclock << 5) / 1000 / rate * (vs + 1) - (1 << 5);
> +	line_thresh = line_thresh1 - line_thresh2 / mhdp->link.num_lanes;
> +	line_thresh = (line_thresh >> 5) + 2;
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_LINE_THRESH,
> +			    line_thresh & GENMASK(5, 0));
> +
> +	cdns_mhdp_reg_write(mhdp, CDNS_DP_RATE_GOVERNOR_STATUS,
> +			    CDNS_DP_RG_TU_VS_DIFF((tu_size - vs > 3) ?
> +						       0 : tu_size - vs));
> +
> +	cdns_mhdp_set_video_status(mhdp, 1);
> +}
> +
> +static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
> +	.enable = cdns_mhdp_enable,
> +	.disable = cdns_mhdp_disable,
> +	.attach = cdns_mhdp_attach,
> +};
> +
> +static int load_firmware(struct cdns_mhdp_device *mhdp, const char *name,
> +			 unsigned int addr)
> +{
> +	const struct firmware *fw;
> +	int ret;
> +
> +	ret = request_firmware(&fw, name, mhdp->dev);
> +	if (ret) {
> +		dev_err(mhdp->dev, "failed to load firmware (%s), ret: %d\n",
> +			name, ret);
> +		return ret;
> +	}
> +
> +	memcpy_toio(mhdp->regs + addr, fw->data, fw->size);
> +
> +	release_firmware(fw);
> +
> +	return 0;
> +}
> +
> +static int cdns_mhdp_audio_hw_params(struct device *dev, void *data,
> +				     struct hdmi_codec_daifmt *daifmt,
> +				     struct hdmi_codec_params *params)
> +{
> +	struct cdns_mhdp_device *mhdp = dev_get_drvdata(dev);
> +	struct audio_info audio = {
> +		.sample_width = params->sample_width,
> +		.sample_rate = params->sample_rate,
> +		.channels = params->channels,
> +	};
> +	int ret;
> +
> +	if (daifmt->fmt != HDMI_I2S) {
> +		DRM_DEV_ERROR(dev, "Invalid format %d\n", daifmt->fmt);
> +		return -EINVAL;
> +	}
> +
> +	audio.format = AFMT_I2S;
> +
> +	ret = cdns_mhdp_audio_config(mhdp, &audio);
> +	if (!ret)
> +		mhdp->audio_info = audio;
> +
> +	return 0;
> +}
> +
> +static void cdns_mhdp_audio_shutdown(struct device *dev, void *data)
> +{
> +	struct cdns_mhdp_device *mhdp = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = cdns_mhdp_audio_stop(mhdp, &mhdp->audio_info);
> +	if (!ret)
> +		mhdp->audio_info.format = AFMT_UNUSED;
> +}
> +
> +static int cdns_mhdp_audio_digital_mute(struct device *dev, void *data,
> +					bool enable)
> +{
> +	struct cdns_mhdp_device *mhdp = dev_get_drvdata(dev);
> +
> +	return cdns_mhdp_audio_mute(mhdp, enable);
> +}
> +
> +static int cdns_mhdp_audio_get_eld(struct device *dev, void *data,
> +				   u8 *buf, size_t len)
> +{
> +	struct cdns_mhdp_device *mhdp = dev_get_drvdata(dev);
> +
> +	memcpy(buf, mhdp->connector.eld,
> +	       min(sizeof(mhdp->connector.eld), len));
> +
> +	return 0;
> +}
> +
> +static const struct hdmi_codec_ops audio_codec_ops = {
> +	.hw_params = cdns_mhdp_audio_hw_params,
> +	.audio_shutdown = cdns_mhdp_audio_shutdown,
> +	.digital_mute = cdns_mhdp_audio_digital_mute,
> +	.get_eld = cdns_mhdp_audio_get_eld,
> +};
> +
> +static int mhdp_probe(struct platform_device *pdev)
> +{
> +	struct resource *regs;
> +	struct cdns_mhdp_device *mhdp;
> +	struct clk *clk;
> +	int ret;
> +	unsigned int reg;
> +	unsigned long rate;
> +	u32 resp;
> +
> +	struct hdmi_codec_pdata codec_data = {
> +		.i2s = 1,
> +		.max_i2s_channels = 8,
> +		.ops = &audio_codec_ops,
> +	};
> +
> +	mhdp = devm_kzalloc(&pdev->dev, sizeof(struct cdns_mhdp_device),
> +			    GFP_KERNEL);
> +	if (!mhdp)
> +		return -ENOMEM;
> +
> +	clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(clk)) {
> +		dev_err(&pdev->dev, "couldn't get clk: %ld\n", PTR_ERR(clk));
> +		return PTR_ERR(clk);
> +	}
> +
> +	mhdp->dev = &pdev->dev;
> +	dev_set_drvdata(&pdev->dev, mhdp);
> +
> +	drm_dp_aux_init(&mhdp->aux);
> +	mhdp->aux.dev = &pdev->dev;
> +	mhdp->aux.transfer = mhdp_transfer;
> +
> +	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	mhdp->regs = devm_ioremap_resource(&pdev->dev, regs);
> +	if (IS_ERR(mhdp->regs))
> +		return PTR_ERR(mhdp->regs);
> +
> +	platform_set_drvdata(pdev, mhdp);
> +
> +	ret = load_firmware(mhdp, FW_NAME, CDNS_MHDP_IMEM);
> +	if (ret)
> +		return ret;
> +
> +	rate = clk_get_rate(clk);
> +	writel(rate % 1000000, mhdp->regs + CDNS_SW_CLK_L);
> +	writel(rate / 1000000, mhdp->regs + CDNS_SW_CLK_H);
> +
> +	/* Leave debug mode */
> +	writel(0, mhdp->regs + CDNS_APB_CTRL);
> +
> +	/*
> +	 * Wait for the KEEP_ALIVE "message" on the first 8 bits.
> +	 * Updated each sched "tick" (~2ms)
> +	 */
> +	ret = readl_poll_timeout(mhdp->regs + CDNS_KEEP_ALIVE, reg,
> +				 reg & CDNS_KEEP_ALIVE_MASK, 500,
> +				 CDNS_KEEP_ALIVE_TIMEOUT);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"device didn't give any life sign: reg %d\n", reg);
> +		return -EIO;
> +	}
> +
> +	/*
> +	 * FIXME (CDNS): how are the characteristics/features of the host
> +	 * defined? Will they be always hardcoded?


At the begining they can be hardcoded, unless there is already
infrastructure to get them from.


> +	 */
> +	/* FIXME: link rate 2.7; num_lanes = 2,	 */


What does it mean?


> +	/* FIXME: read capabilities from PHY */

> +	mhdp->host.link_rate = drm_dp_bw_code_to_link_rate(DP_LINK_BW_5_4);
> +	mhdp->host.lanes_cnt = CDNS_LANE_4 | CDNS_SCRAMBLER;
> +	mhdp->host.volt_swing = CDNS_VOLT_SWING(3);
> +	mhdp->host.pre_emphasis = CDNS_PRE_EMPHASIS(2);
> +	mhdp->host.pattern_supp = CDNS_SUPPORT_TPS(1) |
> +		CDNS_SUPPORT_TPS(2) | CDNS_SUPPORT_TPS(3) |
> +		CDNS_SUPPORT_TPS(4);
> +	mhdp->host.fast_link = 0;
> +	mhdp->host.lane_mapping = CDNS_LANE_MAPPING_FLIPPED;
> +	mhdp->host.enhanced = true;
> +
> +	mhdp->bridge.of_node = pdev->dev.of_node;
> +	mhdp->bridge.funcs = &cdns_mhdp_bridge_funcs;
> +
> +	/* Init events to 0 as it's not cleared by FW at boot but on read */
> +	readl(mhdp->regs + CDNS_SW_EVENT0);
> +	readl(mhdp->regs + CDNS_SW_EVENT1);
> +	readl(mhdp->regs + CDNS_SW_EVENT2);
> +	readl(mhdp->regs + CDNS_SW_EVENT3);
> +
> +	/* Activate uCPU */
> +	ret = cdns_mhdp_set_firmware_active(mhdp, true);
> +	if (ret) {
> +		dev_err(mhdp->dev, "Failed to activate DP\n");
> +		return ret;
> +	}
> +
> +	mhdp->audio_pdev = platform_device_register_data(
> +			   mhdp->dev, HDMI_CODEC_DRV_NAME, PLATFORM_DEVID_AUTO,
> +			   &codec_data, sizeof(codec_data));
> +
> +	/* Enable VIF clock for stream 0 */
> +	cdns_mhdp_reg_read(mhdp, CDNS_DPTX_CAR, &resp);
> +	cdns_mhdp_reg_write(mhdp, CDNS_DPTX_CAR,
> +			    resp | CDNS_VIF_CLK_EN | CDNS_VIF_CLK_RSTN);
> +
> +	/* Loop over HDP change */
> +	/*
> +	 * FIXME: does not work when put in mhdp_bridge_enable.
> +	 * Where should we put it?


It would be good to get rid of these fixmes before final version.

It would be also good to have review from displayport developers - I do
not know DP too much, but I suspect all this link training could be
improved.


Regards

Andrzej


> +	 */
> +	/* Is it still needed with use of mb message HPD STATUS? */
> +	ret = readl_poll_timeout(mhdp->regs + CDNS_SW_EVENT0, reg,
> +				 reg & CDNS_DPTX_HPD, 500,
> +				 CDNS_SW_EVENT0_TIMEOUT);
> +	if (ret) {
> +		dev_err(mhdp->dev, "no HPD received %d\n", reg);
> +		return -ENODEV;
> +	}
> +
> +	drm_bridge_add(&mhdp->bridge);
> +
> +	return 0;
> +}
> +
> +MODULE_FIRMWARE(FW_NAME);
> +
> +static int mhdp_remove(struct platform_device *pdev)
> +{
> +	struct cdns_mhdp_device *mhdp = dev_get_drvdata(&pdev->dev);
> +	int ret;
> +
> +	platform_device_unregister(mhdp->audio_pdev);
> +
> +	drm_bridge_remove(&mhdp->bridge);
> +
> +	ret = cdns_mhdp_set_firmware_active(mhdp, false);
> +	if (ret) {
> +		dev_err(mhdp->dev, "Failed to de-activate DP\n");
> +		return ret;
> +	}
> +
> +	/* FIXME: check for missing functions */
> +
> +	return 0;
> +}
> +
> +static struct platform_driver mhdp_driver = {
> +	.driver	= {
> +		.name		= "cdns-mhdp",
> +		.of_match_table	= of_match_ptr(mhdp_ids),
> +	},
> +	.probe	= mhdp_probe,
> +	.remove	= mhdp_remove,
> +};
> +module_platform_driver(mhdp_driver);
> +
> +MODULE_AUTHOR("Quentin Schulz <quentin.schulz@free-electrons.com>");
> +MODULE_DESCRIPTION("Cadence MHDP DP bridge driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:cdns-mhdp");
> diff --git a/drivers/gpu/drm/rockchip/Kconfig b/drivers/gpu/drm/rockchip/Kconfig
> index 26438d45732b..bd6454b590a2 100644
> --- a/drivers/gpu/drm/rockchip/Kconfig
> +++ b/drivers/gpu/drm/rockchip/Kconfig
> @@ -28,7 +28,9 @@ config ROCKCHIP_ANALOGIX_DP
>  
>  config ROCKCHIP_CDN_DP
>          bool "Rockchip cdn DP"
> -	depends on EXTCON=y || (EXTCON=m && DRM_ROCKCHIP=m)
> +	depends on DRM_ROCKCHIP
> +	select EXTCON
> +	select DRM_CDNS_MHDP
>          help
>  	  This selects support for Rockchip SoC specific extensions
>  	  for the cdn DP driver. If you want to enable Dp on
> diff --git a/drivers/gpu/drm/rockchip/Makefile b/drivers/gpu/drm/rockchip/Makefile
> index 868263ff0302..c908a4fb8a47 100644
> --- a/drivers/gpu/drm/rockchip/Makefile
> +++ b/drivers/gpu/drm/rockchip/Makefile
> @@ -9,7 +9,7 @@ rockchipdrm-y := rockchip_drm_drv.o rockchip_drm_fb.o \
>  rockchipdrm-$(CONFIG_DRM_FBDEV_EMULATION) += rockchip_drm_fbdev.o
>  
>  rockchipdrm-$(CONFIG_ROCKCHIP_ANALOGIX_DP) += analogix_dp-rockchip.o
> -rockchipdrm-$(CONFIG_ROCKCHIP_CDN_DP) += cdn-dp-core.o cdn-dp-reg.o
> +rockchipdrm-$(CONFIG_ROCKCHIP_CDN_DP) += cdn-dp-core.o
>  rockchipdrm-$(CONFIG_ROCKCHIP_DW_HDMI) += dw_hdmi-rockchip.o
>  rockchipdrm-$(CONFIG_ROCKCHIP_DW_MIPI_DSI) += dw-mipi-dsi.o
>  rockchipdrm-$(CONFIG_ROCKCHIP_INNO_HDMI) += inno_hdmi.o
> diff --git a/drivers/gpu/drm/rockchip/cdn-dp-core.c b/drivers/gpu/drm/rockchip/cdn-dp-core.c
> index bf7e206326f0..343f381e3440 100644
> --- a/drivers/gpu/drm/rockchip/cdn-dp-core.c
> +++ b/drivers/gpu/drm/rockchip/cdn-dp-core.c
> @@ -816,7 +816,7 @@ static int cdn_dp_audio_hw_params(struct device *dev,  void *data,
>  
>  	ret = cdns_mhdp_audio_config(&dp->mhdp, &audio);
>  	if (!ret)
> -		dp->audio_info = audio;
> +		dp->mhdp.audio_info = audio;
>  
>  out:
>  	mutex_unlock(&dp->lock);
> @@ -832,9 +832,9 @@ static void cdn_dp_audio_shutdown(struct device *dev, void *data)
>  	if (!dp->active)
>  		goto out;
>  
> -	ret = cdns_mhdp_audio_stop(&dp->mhdp, &dp->audio_info);
> +	ret = cdns_mhdp_audio_stop(&dp->mhdp, &dp->mhdp.audio_info);
>  	if (!ret)
> -		dp->audio_info.format = AFMT_UNUSED;
> +		dp->mhdp.audio_info.format = AFMT_UNUSED;
>  out:
>  	mutex_unlock(&dp->lock);
>  }
> @@ -886,11 +886,11 @@ static int cdn_dp_audio_codec_init(struct cdn_dp_device *dp,
>  		.max_i2s_channels = 8,
>  	};
>  
> -	dp->audio_pdev = platform_device_register_data(
> -			 dev, HDMI_CODEC_DRV_NAME, PLATFORM_DEVID_AUTO,
> -			 &codec_data, sizeof(codec_data));
> +	dp->mhdp.audio_pdev = platform_device_register_data(
> +			      dev, HDMI_CODEC_DRV_NAME, PLATFORM_DEVID_AUTO,
> +			      &codec_data, sizeof(codec_data));
>  
> -	return PTR_ERR_OR_ZERO(dp->audio_pdev);
> +	return PTR_ERR_OR_ZERO(dp->mhdp.audio_pdev);
>  }
>  
>  static int cdn_dp_request_firmware(struct cdn_dp_device *dp)
> @@ -1217,7 +1217,7 @@ static int cdn_dp_remove(struct platform_device *pdev)
>  {
>  	struct cdn_dp_device *dp = platform_get_drvdata(pdev);
>  
> -	platform_device_unregister(dp->audio_pdev);
> +	platform_device_unregister(dp->mhdp.audio_pdev);
>  	cdn_dp_suspend(dp->mhdp.dev);
>  	component_del(&pdev->dev, &cdn_dp_component_ops);
>  
> diff --git a/drivers/gpu/drm/rockchip/cdn-dp-core.h b/drivers/gpu/drm/rockchip/cdn-dp-core.h
> index bad65c2fe610..a086dad31287 100644
> --- a/drivers/gpu/drm/rockchip/cdn-dp-core.h
> +++ b/drivers/gpu/drm/rockchip/cdn-dp-core.h
> @@ -19,8 +19,9 @@
>  #include <drm/drm_crtc_helper.h>
>  #include <drm/drm_dp_helper.h>
>  #include <drm/drm_panel.h>
> +#include <drm/bridge/cdns-mhdp-common.h>
> +
>  #include "rockchip_drm_drv.h"
> -#include "cdn-dp-reg.h"
>  
>  #define MAX_PHY		2
>  
> @@ -45,7 +46,6 @@ struct cdn_dp_device {
>  	struct cdns_mhdp_device mhdp;
>  	struct drm_device *drm_dev;
>  	struct drm_encoder encoder;
> -	struct platform_device *audio_pdev;
>  	struct work_struct event_work;
>  	struct edid *edid;
>  
> @@ -64,7 +64,6 @@ struct cdn_dp_device {
>  	struct reset_control *dptx_rst;
>  	struct reset_control *apb_rst;
>  	struct reset_control *core_rst;
> -	struct audio_info audio_info;
>  	struct cdn_dp_port *port[MAX_PHY];
>  	u8 ports;
>  	u8 lanes;
> diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.h b/include/drm/bridge/cdns-mhdp-common.h
> similarity index 95%
> rename from drivers/gpu/drm/rockchip/cdn-dp-reg.h
> rename to include/drm/bridge/cdns-mhdp-common.h
> index 3cb40d719515..c5a5c4fa7fc4 100644
> --- a/drivers/gpu/drm/rockchip/cdn-dp-reg.h
> +++ b/include/drm/bridge/cdns-mhdp-common.h
> @@ -12,10 +12,13 @@
>   * GNU General Public License for more details.
>   */
>  
> -#ifndef _CDN_DP_REG_H
> -#define _CDN_DP_REG_H
> +#ifndef CDNS_MHDP_COMMON_H_
> +#define CDNS_MHDP_COMMON_H_
>  
>  #include <linux/bitops.h>
> +#include <drm/drm_dp_helper.h>
> +#include <drm/drm_connector.h>
> +#include <drm/drm_bridge.h>
>  
>  #define ADDR_IMEM		0x10000
>  #define ADDR_DMEM		0x20000
> @@ -327,6 +330,7 @@
>  #define GENERAL_TEST_ECHO               0x02
>  #define GENERAL_BUS_SETTINGS            0x03
>  #define GENERAL_TEST_ACCESS             0x04
> +#define GENERAL_REGISTER_READ           0x07
>  
>  #define DPTX_SET_POWER_MNG			0x00
>  #define DPTX_SET_HOST_CAPABILITIES		0x01
> @@ -346,6 +350,7 @@
>  #define DPTX_SET_LINK_BREAK_POINT		0x0f
>  #define DPTX_FORCE_LANES			0x10
>  #define DPTX_HPD_STATE				0x11
> +#define DPTX_ADJUST_LT				0x12
>  
>  #define FW_STANDBY				0
>  #define FW_ACTIVE				1
> @@ -517,6 +522,9 @@ struct cdns_mhdp_device {
>  	struct clk		*spdif_clk;
>  	struct reset_control	*spdif_rst;
>  
> +	struct platform_device	*audio_pdev;
> +	struct audio_info	audio_info;
> +
>  	struct drm_dp_aux	aux;
>  	struct cdns_mhdp_host	host;
>  	struct cdns_mhdp_sink	sink;
> @@ -551,4 +559,11 @@ int cdns_mhdp_audio_stop(struct cdns_mhdp_device *mhdp,
>  int cdns_mhdp_audio_mute(struct cdns_mhdp_device *mhdp, bool enable);
>  int cdns_mhdp_audio_config(struct cdns_mhdp_device *mhdp,
>  			   struct audio_info *audio);
> -#endif /* _CDN_DP_REG_H */
> +int cdns_mhdp_reg_read(struct cdns_mhdp_device *mhdp, u32 addr, u32 *value);
> +int cdns_mhdp_reg_write(struct cdns_mhdp_device *mhdp, u16 addr, u32 val);
> +int cdns_mhdp_reg_write_bit(struct cdns_mhdp_device *mhdp, u16 addr,
> +				   u8 start_bit, u8 bits_no, u32 val);
> +int cdns_mhdp_adjust_lt(struct cdns_mhdp_device *mhdp, u8 nlanes,
> +			u16 udelay, u8 *lanes_data,
> +			u8 *dpcd);
> +#endif /* CDNS_MHDP_COMMON_H_ */