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Subject: Re: [PATCH v2 2/2] drm/bridge: Add tc358768 driver
To:     Peter Ujfalusi <peter.ujfalusi@ti.com>, airlied@linux.ie,
        daniel@ffwll.ch, robh+dt@kernel.org, mark.rutland@arm.com,
        narmstrong@baylibre.com
Cc:     devicetree@vger.kernel.org, jernej.skrabec@siol.net,
        jonas@kwiboo.se, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, tomi.valkeinen@ti.com,
        Laurent.pinchart@ideasonboard.com
From:   Andrzej Hajda <a.hajda@samsung.com>
Message-ID: <d83804cc-3ebf-cb1a-9168-686fe3669d1b@samsung.com>
Date:   Fri, 24 Jan 2020 15:27:45 +0100
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        <CGME20200124105526eucas1p2085fcb6963697bee59cc96edb20d44a1@eucas1p2.samsung.com>
        <20200124105537.21651-3-peter.ujfalusi@ti.com>
Sender: linux-kernel-owner@vger.kernel.org
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On 24.01.2020 11:55, Peter Ujfalusi wrote:
> Add basic support for the Toshiba TC358768 RGB to DSI bridge.
> Not all the features of the TC358768 is implemented by the initial driver:
> MIPI_DSI_MODE_VIDEO and MIPI_DSI_FMT_RGB888 is only supported and tested.
>
> Only write is implemented for mipi_dsi_host_ops.transfer.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> ---
>  drivers/gpu/drm/bridge/Kconfig    |  10 +
>  drivers/gpu/drm/bridge/Makefile   |   1 +
>  drivers/gpu/drm/bridge/tc358768.c | 992 ++++++++++++++++++++++++++++++
>  3 files changed, 1003 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/tc358768.c
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 0b9ca5862455..3fef3513bdd0 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -122,6 +122,16 @@ config DRM_TOSHIBA_TC358767
>  	---help---
>  	  Toshiba TC358767 eDP bridge chip driver.
>  
> +config DRM_TOSHIBA_TC358768
> +	tristate "Toshiba TC358768 MIPI DSI bridge"
> +	depends on OF
> +	select DRM_KMS_HELPER
> +	select REGMAP_I2C
> +	select DRM_PANEL
> +	select DRM_MIPI_DSI
> +	help
> +	  Toshiba TC358768AXBG/TC358778XBG DSI bridge chip driver.
> +
>  config DRM_TI_TFP410
>  	tristate "TI TFP410 DVI/HDMI bridge"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index cd16ce830270..06fc265de0ef 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_DRM_SII9234) += sii9234.o
>  obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358764) += tc358764.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
> +obj-$(CONFIG_DRM_TOSHIBA_TC358768) += tc358768.o
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
> new file mode 100644
> index 000000000000..5e12b1390254
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/tc358768.c
> @@ -0,0 +1,992 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + *  Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com
> + *  Author: Peter Ujfalusi <peter.ujfalusi@ti.com>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_drv.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <video/mipi_display.h>
> +#include <video/videomode.h>
> +
> +/* Global (16-bit addressable) */
> +#define TC358768_CHIPID			0x0000
> +#define TC358768_SYSCTL			0x0002
> +#define TC358768_CONFCTL		0x0004
> +#define TC358768_VSDLY			0x0006
> +#define TC358768_DATAFMT		0x0008
> +#define TC358768_GPIOEN			0x000E
> +#define TC358768_GPIODIR		0x0010
> +#define TC358768_GPIOIN			0x0012
> +#define TC358768_GPIOOUT		0x0014
> +#define TC358768_PLLCTL0		0x0016
> +#define TC358768_PLLCTL1		0x0018
> +#define TC358768_CMDBYTE		0x0022
> +#define TC358768_PP_MISC		0x0032
> +#define TC358768_DSITX_DT		0x0050
> +#define TC358768_FIFOSTATUS		0x00F8
> +
> +/* Debug (16-bit addressable) */
> +#define TC358768_VBUFCTRL		0x00E0
> +#define TC358768_DBG_WIDTH		0x00E2
> +#define TC358768_DBG_VBLANK		0x00E4
> +#define TC358768_DBG_DATA		0x00E8
> +
> +/* TX PHY (32-bit addressable) */
> +#define TC358768_CLW_DPHYCONTTX		0x0100
> +#define TC358768_D0W_DPHYCONTTX		0x0104
> +#define TC358768_D1W_DPHYCONTTX		0x0108
> +#define TC358768_D2W_DPHYCONTTX		0x010C
> +#define TC358768_D3W_DPHYCONTTX		0x0110
> +#define TC358768_CLW_CNTRL		0x0140
> +#define TC358768_D0W_CNTRL		0x0144
> +#define TC358768_D1W_CNTRL		0x0148
> +#define TC358768_D2W_CNTRL		0x014C
> +#define TC358768_D3W_CNTRL		0x0150
> +
> +/* TX PPI (32-bit addressable) */
> +#define TC358768_STARTCNTRL		0x0204
> +#define TC358768_DSITXSTATUS		0x0208
> +#define TC358768_LINEINITCNT		0x0210
> +#define TC358768_LPTXTIMECNT		0x0214
> +#define TC358768_TCLK_HEADERCNT		0x0218
> +#define TC358768_TCLK_TRAILCNT		0x021C
> +#define TC358768_THS_HEADERCNT		0x0220
> +#define TC358768_TWAKEUP		0x0224
> +#define TC358768_TCLK_POSTCNT		0x0228
> +#define TC358768_THS_TRAILCNT		0x022C
> +#define TC358768_HSTXVREGCNT		0x0230
> +#define TC358768_HSTXVREGEN		0x0234
> +#define TC358768_TXOPTIONCNTRL		0x0238
> +#define TC358768_BTACNTRL1		0x023C
> +
> +/* TX CTRL (32-bit addressable) */
> +#define TC358768_DSI_CONTROL		0x040C
> +#define TC358768_DSI_STATUS		0x0410
> +#define TC358768_DSI_INT		0x0414
> +#define TC358768_DSI_INT_ENA		0x0418
> +#define TC358768_DSICMD_RDFIFO		0x0430
> +#define TC358768_DSI_ACKERR		0x0434
> +#define TC358768_DSI_ACKERR_INTENA	0x0438
> +#define TC358768_DSI_ACKERR_HALT	0x043c
> +#define TC358768_DSI_RXERR		0x0440
> +#define TC358768_DSI_RXERR_INTENA	0x0444
> +#define TC358768_DSI_RXERR_HALT		0x0448
> +#define TC358768_DSI_ERR		0x044C
> +#define TC358768_DSI_ERR_INTENA		0x0450
> +#define TC358768_DSI_ERR_HALT		0x0454
> +#define TC358768_DSI_CONFW		0x0500
> +#define TC358768_DSI_LPCMD		0x0500
> +#define TC358768_DSI_RESET		0x0504
> +#define TC358768_DSI_INT_CLR		0x050C
> +#define TC358768_DSI_START		0x0518
> +
> +/* DSITX CTRL (16-bit addressable) */
> +#define TC358768_DSICMD_TX		0x0600
> +#define TC358768_DSICMD_TYPE		0x0602
> +#define TC358768_DSICMD_WC		0x0604
> +#define TC358768_DSICMD_WD0		0x0610
> +#define TC358768_DSICMD_WD1		0x0612
> +#define TC358768_DSICMD_WD2		0x0614
> +#define TC358768_DSICMD_WD3		0x0616
> +#define TC358768_DSI_EVENT		0x0620
> +#define TC358768_DSI_VSW		0x0622
> +#define TC358768_DSI_VBPR		0x0624
> +#define TC358768_DSI_VACT		0x0626
> +#define TC358768_DSI_HSW		0x0628
> +#define TC358768_DSI_HBPR		0x062A
> +#define TC358768_DSI_HACT		0x062C
> +
> +static const char * const tc358768_supplies[] = {
> +	"vddc", "vddmipi", "vddio"
> +};
> +
> +struct tc358768_dsi_output {
> +	struct mipi_dsi_device *dev;
> +	struct drm_panel *panel;
> +	struct drm_bridge *bridge;
> +};
> +
> +struct tc358768_priv {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct gpio_desc *reset_gpio;
> +	struct regulator_bulk_data supplies[ARRAY_SIZE(tc358768_supplies)];
> +	struct clk *refclk;
> +	int enabled;
> +	int error;
> +
> +	struct mipi_dsi_host dsi_host;
> +	struct drm_bridge bridge;
> +	struct tc358768_dsi_output output;
> +
> +	u32 pd_lines; /* number of Parallel Port Input Data Lines */
> +	u32 dsi_lanes; /* number of DSI Lanes */
> +
> +	/* Parameters for PLL programming */
> +	u32 fbd;	/* PLL feedback divider */
> +	u32 prd;	/* PLL input divider */
> +	u32 frs;	/* PLL Freqency range for HSCK (post divider) */
> +
> +	u32 dsiclk;	/* pll_clk / 2 */
> +};
> +
> +static inline struct tc358768_priv *dsi_host_to_tc358768(struct mipi_dsi_host
> +							 *host)
> +{
> +	return container_of(host, struct tc358768_priv, dsi_host);
> +}
> +
> +static inline struct tc358768_priv *bridge_to_tc358768(struct drm_bridge
> +						       *bridge)
> +{
> +	return container_of(bridge, struct tc358768_priv, bridge);
> +}
> +
> +static int tc358768_clear_error(struct tc358768_priv *priv)
> +{
> +	int ret = priv->error;
> +
> +	priv->error = 0;
> +	return ret;
> +}
> +
> +static void tc358768_write(struct tc358768_priv *priv, u32 reg, u32 val)
> +{
> +	size_t count = 2;
> +
> +	if (priv->error)
> +		return;
> +
> +	/* 16-bit register? */
> +	if (reg < 0x100 || reg >= 0x600)
> +		count = 1;
> +
> +	priv->error = regmap_bulk_write(priv->regmap, reg, &val, count);


Maybe it would be good to log possible error here and after regmap*read,
to have more precise info, unless such log is provided already by
regmap, up to you.


> +}
> +
> +static void tc358768_read(struct tc358768_priv *priv, u32 reg, u32 *val)
> +{
> +	size_t count = 2;
> +
> +	if (priv->error)
> +		return;
> +
> +	/* 16-bit register? */
> +	if (reg < 0x100 || reg >= 0x600) {
> +		*val = 0;
> +		count = 1;
> +	}
> +
> +	priv->error = regmap_bulk_read(priv->regmap, reg, val, count);
> +}
> +
> +static void tc358768_update_bits(struct tc358768_priv *priv, u32 reg, u32 mask,
> +				 u32 val)
> +{
> +	u32 tmp, orig;
> +
> +	tc358768_read(priv, reg, &orig);
> +	tmp = orig & ~mask;
> +	tmp |= val & mask;
> +	if (tmp != orig)
> +		tc358768_write(priv, reg, tmp);
> +}
> +
> +static int tc358768_sw_reset(struct tc358768_priv *priv)
> +{
> +	/* Assert Reset */
> +	tc358768_write(priv, TC358768_SYSCTL, 1);
> +	/* Release Reset, Exit Sleep */
> +	tc358768_write(priv, TC358768_SYSCTL, 0);
> +
> +	return tc358768_clear_error(priv);
> +}
> +
> +static void tc358768_hw_enable(struct tc358768_priv *priv)
> +{
> +	int ret;
> +
> +	if (priv->enabled++ > 0)
> +		return;
> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(priv->supplies), priv->supplies);
> +	if (ret < 0)
> +		dev_err(priv->dev, "error enabling regulators (%d)\n", ret);
> +
> +	if (priv->reset_gpio)
> +		usleep_range(200, 300);
> +
> +	/*
> +	 * The RESX is active low (GPIO_ACTIVE_LOW).
> +	 * DEASSERT (value = 0) the reset_gpio to enable the chip
> +	 */
> +	gpiod_set_value_cansleep(priv->reset_gpio, 0);
> +
> +	/* wait for encoder clocks to stabilize */
> +	usleep_range(1000, 2000);
> +}
> +
> +static void tc358768_hw_disable(struct tc358768_priv *priv)
> +{
> +	int ret;
> +
> +	if (--priv->enabled != 0)
> +		return;
> +
> +	/*
> +	 * The RESX is active low (GPIO_ACTIVE_LOW).
> +	 * ASSERT (value = 1) the reset_gpio to disable the chip
> +	 */
> +	gpiod_set_value_cansleep(priv->reset_gpio, 1);
> +
> +	ret = regulator_bulk_disable(ARRAY_SIZE(priv->supplies),
> +				     priv->supplies);
> +	if (ret < 0)
> +		dev_err(priv->dev, "error disabling regulators (%d)\n", ret);
> +}
> +
> +static u32 tc358768_pll_to_pclk(struct tc358768_priv *priv, u32 pll_clk)
> +{
> +	return (u32)div_u64((u64)pll_clk * priv->dsi_lanes, priv->pd_lines);
> +}
> +
> +static u32 tc358768_pclk_to_pll(struct tc358768_priv *priv, u32 pclk)
> +{
> +	return (u32)div_u64((u64)pclk * priv->pd_lines, priv->dsi_lanes);
> +}
> +
> +static int tc358768_calc_pll(struct tc358768_priv *priv,
> +			     const struct drm_display_mode *mode,
> +			     bool verify_only)
> +{
> +	const u32 frs_limits[] = {
> +		1000000000,
> +		500000000,
> +		250000000,
> +		125000000,
> +		62500000
> +	};
> +	unsigned long refclk;
> +	u32 prd, target_pll, i, max_pll, min_pll;
> +	u32 frs, best_diff, best_pll, best_prd, best_fbd;
> +
> +	target_pll = tc358768_pclk_to_pll(priv, mode->clock * 1000);
> +
> +	/* pll_clk = RefClk * [(FBD + 1)/ (PRD + 1)] * [1 / (2^FRS)] */
> +
> +	for (i = 0; i < ARRAY_SIZE(frs_limits); i++)
> +		if (target_pll >= frs_limits[i])
> +			break;
> +
> +	if (i == ARRAY_SIZE(frs_limits) || i == 0)
> +		return -EINVAL;
> +
> +	frs = i - 1;
> +	max_pll = frs_limits[i - 1];
> +	min_pll = frs_limits[i];
> +
> +	refclk = clk_get_rate(priv->refclk);
> +
> +	best_diff = UINT_MAX;
> +	best_pll = 0;
> +	best_prd = 0;
> +	best_fbd = 0;
> +
> +	for (prd = 0; prd < 16; ++prd) {
> +		u32 divisor = (prd + 1) * (1 << frs);
> +		u32 fbd;
> +
> +		for (fbd = 0; fbd < 512; ++fbd) {
> +			u32 pll, diff;
> +
> +			pll = (u32)div_u64((u64)refclk * (fbd + 1), divisor);
> +
> +			if (pll >= max_pll || pll < min_pll)
> +				continue;
> +
> +			diff = max(pll, target_pll) - min(pll, target_pll);
> +
> +			if (diff < best_diff) {
> +				best_diff = diff;
> +				best_pll = pll;
> +				best_prd = prd;
> +				best_fbd = fbd;
> +			}
> +
> +			if (best_diff == 0)
> +				goto found;


More optimal would be put above check inside block few lines above, at
the cost of another indent, up to you.


> +		}
> +	}
> +
> +found:
> +	if (best_diff == UINT_MAX) {
> +		dev_err(priv->dev, "could not find suitable PLL setup\n");
> +		return -EINVAL;
> +	}
> +
> +	if (verify_only)
> +		return 0;
> +
> +	priv->fbd = best_fbd;
> +	priv->prd = best_prd;
> +	priv->frs = frs;
> +	priv->dsiclk = best_pll / 2;
> +
> +	return 0;
> +}
> +
> +static int tc358768_dsi_host_attach(struct mipi_dsi_host *host,
> +				    struct mipi_dsi_device *dev)
> +{
> +	struct tc358768_priv *priv = dsi_host_to_tc358768(host);
> +	struct drm_bridge *bridge;
> +	struct drm_panel *panel;
> +	struct device_node *ep;
> +	int ret;
> +
> +	if (dev->lanes > 4) {
> +		dev_err(priv->dev, "unsupported number of data lanes(%u)\n",
> +			dev->lanes);
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * tc358768 supports both Video and Pulse mode, but the driver only
> +	 * implements Video (event) mode currently
> +	 */
> +	if (!(dev->mode_flags & MIPI_DSI_MODE_VIDEO)) {
> +		dev_err(priv->dev, "Only MIPI_DSI_MODE_VIDEO is supported\n");
> +		return -ENOTSUPP;
> +	}
> +
> +	/*
> +	 * tc358768 supports RGB888, RGB666, RGB666_PACKED and RGB565, but only
> +	 * RGB888 is verified.
> +	 */
> +	if (dev->format != MIPI_DSI_FMT_RGB888) {
> +		dev_warn(priv->dev, "Only MIPI_DSI_FMT_RGB888 tested!\n");
> +		return -ENOTSUPP;
> +	}
> +
> +	ret = drm_of_find_panel_or_bridge(host->dev->of_node, 1, 0, &panel,
> +					  &bridge);
> +	if (ret)
> +		return ret;
> +
> +	if (panel) {
> +		bridge = drm_panel_bridge_add_typed(panel,
> +						    DRM_MODE_CONNECTOR_DSI);
> +		if (IS_ERR(bridge))
> +			return PTR_ERR(bridge);
> +	}
> +
> +	priv->output.dev = dev;
> +	priv->output.bridge = bridge;
> +	priv->output.panel = panel;
> +
> +	priv->dsi_lanes = dev->lanes;
> +
> +	/* get input ep (port0/endpoint0) */
> +	ret = -EINVAL;
> +	ep = of_graph_get_endpoint_by_regs(host->dev->of_node, 0, 0);
> +	if (ep) {
> +		ret = of_property_read_u32(ep, "data-lines", &priv->pd_lines);
> +
> +		of_node_put(ep);
> +	}
> +
> +	if (ret)
> +		priv->pd_lines = mipi_dsi_pixel_format_to_bpp(dev->format);
> +
> +	drm_bridge_add(&priv->bridge);
> +
> +	return 0;
> +}
> +
> +static int tc358768_dsi_host_detach(struct mipi_dsi_host *host,
> +				    struct mipi_dsi_device *dev)
> +{
> +	struct tc358768_priv *priv = dsi_host_to_tc358768(host);
> +
> +	drm_bridge_remove(&priv->bridge);
> +	if (priv->output.panel)
> +		drm_panel_bridge_remove(priv->output.bridge);
> +
> +	return 0;
> +}
> +
> +static ssize_t tc358768_dsi_host_transfer(struct mipi_dsi_host *host,
> +					  const struct mipi_dsi_msg *msg)
> +{
> +	struct tc358768_priv *priv = dsi_host_to_tc358768(host);
> +	struct mipi_dsi_packet packet;
> +	int ret;
> +
> +	if (msg->rx_len) {
> +		dev_warn(priv->dev, "MIPI rx is not supported\n");
> +		return -ENOTSUPP;
> +	}
> +
> +	if (msg->tx_len > 8) {
> +		dev_warn(priv->dev, "Maximum 8 byte MIPI tx is supported\n");
> +		return -ENOTSUPP;
> +	}
> +
> +	ret = mipi_dsi_create_packet(&packet, msg);
> +	if (ret)
> +		return ret;
> +
> +	tc358768_hw_enable(priv);


This looks suspicious, if you put tc358768_hw_enable here it means you
are assuming hw can be disabled when transfer is requested, it means
that after transfer the hardware will be disabled again, I do not think
it is good thing - DSI bus is not designed for short transfers
interleaved with hw enable/disable cycle, I guess it can be even harmful
for downstream devices.

If this is workaround to allow downstream devices initialization in
.pre_enable/.prepare callbacks I guess it can be solved properly by
avoiding bridge->next callback chain, and calling downstream device
opses directly, or we should think about more convenient solution.


> +
> +	if (mipi_dsi_packet_format_is_short(msg->type)) {
> +		tc358768_write(priv, TC358768_DSICMD_TYPE,
> +			       (0x10 << 8) | (packet.header[0] & 0x3f));
> +		tc358768_write(priv, TC358768_DSICMD_WC, 0);
> +		tc358768_write(priv, TC358768_DSICMD_WD0,
> +			       (packet.header[2] << 8) | packet.header[1]);
> +	} else {
> +		int i;
> +
> +		tc358768_write(priv, TC358768_DSICMD_TYPE,
> +			       (0x40 << 8) | (packet.header[0] & 0x3f));
> +		tc358768_write(priv, TC358768_DSICMD_WC, packet.payload_length);
> +		for (i = 0; i < packet.payload_length; i += 2) {
> +			u16 val = packet.payload[i];
> +
> +			if (i + 1 < packet.payload_length)
> +				val |= packet.payload[i + 1] << 8;
> +
> +			tc358768_write(priv, TC358768_DSICMD_WD0 + i, val);
> +		}
> +	}
> +
> +	/* start transfer */
> +	tc358768_write(priv, TC358768_DSICMD_TX, 1);
> +
> +	tc358768_hw_disable(priv);
> +
> +	return tc358768_clear_error(priv);
> +}
> +
> +static const struct mipi_dsi_host_ops tc358768_dsi_host_ops = {
> +	.attach = tc358768_dsi_host_attach,
> +	.detach = tc358768_dsi_host_detach,
> +	.transfer = tc358768_dsi_host_transfer,
> +};
> +
> +static int tc358768_bridge_attach(struct drm_bridge *bridge)
> +{
> +	struct tc358768_priv *priv = bridge_to_tc358768(bridge);
> +
> +	if (!drm_core_check_feature(bridge->dev, DRIVER_ATOMIC)) {
> +		dev_err(priv->dev, "needs atomic updates support\n");
> +		return -ENOTSUPP;
> +	}
> +
> +	return drm_bridge_attach(bridge->encoder, priv->output.bridge, bridge);
> +}
> +
> +static enum drm_mode_status
> +tc358768_bridge_mode_valid(struct drm_bridge *bridge,
> +			   const struct drm_display_mode *mode)
> +{
> +	struct tc358768_priv *priv = bridge_to_tc358768(bridge);
> +
> +	if (tc358768_calc_pll(priv, mode, true))
> +		return MODE_CLOCK_RANGE;
> +
> +	return MODE_OK;
> +}
> +
> +static void tc358768_bridge_disable(struct drm_bridge *bridge)
> +{
> +	struct tc358768_priv *priv = bridge_to_tc358768(bridge);
> +	int ret;
> +
> +	/* set FrmStop */
> +	tc358768_update_bits(priv, TC358768_PP_MISC, BIT(15), BIT(15));
> +
> +	/* wait at least for one frame */
> +	msleep(50);
> +
> +	/* clear PP_en */
> +	tc358768_update_bits(priv, TC358768_CONFCTL, BIT(6), 0);
> +
> +	/* set RstPtr */
> +	tc358768_update_bits(priv, TC358768_PP_MISC, BIT(14), BIT(14));
> +
> +	ret = tc358768_clear_error(priv);
> +	if (ret)
> +		dev_warn(priv->dev, "Software disable failed: %d\n", ret);
> +
> +	tc358768_hw_disable(priv);
> +}
> +
> +static int tc358768_setup_pll(struct tc358768_priv *priv,
> +			      const struct drm_display_mode *mode)
> +{
> +	u32 fbd, prd, frs;
> +	int ret;
> +
> +	ret = tc358768_calc_pll(priv, mode, false);
> +	if (ret) {
> +		dev_err(priv->dev, "PLL calculation failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	fbd = priv->fbd;
> +	prd = priv->prd;
> +	frs = priv->frs;
> +
> +	dev_dbg(priv->dev, "PLL: refclk %lu, fbd %u, prd %u, frs %u\n",
> +		clk_get_rate(priv->refclk), fbd, prd, frs);
> +	dev_dbg(priv->dev, "PLL: pll_clk: %u, DSIClk %u, DSIByteClk %u\n",
> +		priv->dsiclk * 2, priv->dsiclk, priv->dsiclk / 4);
> +	dev_dbg(priv->dev, "PLL: pclk %u (panel: %u)\n",
> +		tc358768_pll_to_pclk(priv, priv->dsiclk * 2),
> +		mode->clock * 1000);
> +
> +	/* PRD[15:12] FBD[8:0] */
> +	tc358768_write(priv, TC358768_PLLCTL0, (prd << 12) | fbd);
> +
> +	/* FRS[11:10] LBWS[9:8] CKEN[4] RESETB[1] EN[0] */
> +	tc358768_write(priv, TC358768_PLLCTL1,
> +		       (frs << 10) | (0x2 << 8) | BIT(1) | BIT(0));
> +
> +	/* wait for lock */
> +	usleep_range(1000, 2000);
> +
> +	/* FRS[11:10] LBWS[9:8] CKEN[4] PLL_CKEN[4] RESETB[1] EN[0] */
> +	tc358768_write(priv, TC358768_PLLCTL1,
> +		       (frs << 10) | (0x2 << 8) | BIT(4) | BIT(1) | BIT(0));
> +
> +	return tc358768_clear_error(priv);
> +}
> +
> +#define TC358768_PRECISION	1000
> +static u32 tc358768_ns_to_cnt(u32 ns, u32 period_nsk)
> +{
> +	return (ns * TC358768_PRECISION + period_nsk) / period_nsk;
> +}
> +
> +static u32 tc358768_to_ns(u32 nsk)
> +{
> +	return (nsk / TC358768_PRECISION);
> +}
> +
> +static void tc358768_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct tc358768_priv *priv = bridge_to_tc358768(bridge);
> +	struct mipi_dsi_device *dsi_dev = priv->output.dev;
> +	u32 val, val2, lptxcnt, hact, data_type;
> +	const struct drm_display_mode *mode;
> +	u32 dsibclk_nsk, dsiclk_nsk, ui_nsk, phy_delay_nsk;
> +	u32 dsiclk, dsibclk;
> +	int ret, i;
> +
> +	tc358768_hw_enable(priv);
> +
> +	ret = tc358768_sw_reset(priv);
> +	if (ret) {
> +		dev_err(priv->dev, "Software reset failed: %d\n", ret);
> +		return;
> +	}


I think above code (maybe more) should go to pre_enable, bridges should
follow quite well established practices for panels [1], ie
bridge.pre_enable should do similar things as panel.prepare, etc,

this can be separated if user requiring it appears.

https://dri.freedesktop.org/docs/drm/gpu/drm-kms-helpers.html?highlight=drm_panel_funcs#c.drm_panel_funcs


> +
> +	mode = &bridge->encoder->crtc->state->adjusted_mode;
> +	ret = tc358768_setup_pll(priv, mode);
> +	if (ret) {
> +		dev_err(priv->dev, "PLL setup failed: %d\n", ret);
> +		return;
> +	}
> +
> +	dsiclk = priv->dsiclk;
> +	dsibclk = dsiclk / 4;
> +
> +	/* Data Format Control Register */
> +	val = BIT(2) | BIT(1) | BIT(0); /* rdswap_en | dsitx_en | txdt_en */
> +	switch (dsi_dev->format) {
> +	case MIPI_DSI_FMT_RGB888:
> +		val |= (0x3 << 4);
> +		hact = mode->hdisplay * 3;
> +		data_type = MIPI_DSI_PACKED_PIXEL_STREAM_24;
> +		break;
> +	case MIPI_DSI_FMT_RGB666:
> +		val |= (0x4 << 4);
> +		hact = mode->hdisplay * 3;
> +		data_type = MIPI_DSI_PACKED_PIXEL_STREAM_18;
> +		break;
> +
> +	case MIPI_DSI_FMT_RGB666_PACKED:
> +		val |= (0x4 << 4) | BIT(3);
> +		hact = mode->hdisplay * 18 / 8;
> +		data_type = MIPI_DSI_PIXEL_STREAM_3BYTE_18;
> +		break;
> +
> +	case MIPI_DSI_FMT_RGB565:
> +		val |= (0x5 << 4);
> +		hact = mode->hdisplay * 2;
> +		data_type = MIPI_DSI_PACKED_PIXEL_STREAM_16;
> +		break;
> +	default:
> +		dev_err(priv->dev, "Invalid data format (%u)\n",
> +			dsi_dev->format);
> +		return;
> +	}
> +
> +	/* VSDly[9:0] */
> +	tc358768_write(priv, TC358768_VSDLY, 1);
> +
> +	tc358768_write(priv, TC358768_DATAFMT, val);
> +	tc358768_write(priv, TC358768_DSITX_DT, data_type);
> +
> +	/* Enable D-PHY (HiZ->LP11) */
> +	tc358768_write(priv, TC358768_CLW_CNTRL, 0x0000);
> +	/* Enable lanes */
> +	for (i = 0; i < dsi_dev->lanes; i++)
> +		tc358768_write(priv, TC358768_D0W_CNTRL + i * 4, 0x0000);
> +
> +	/* DSI Timings */
> +	dsibclk_nsk = (u32)div_u64((u64)1000000000 * TC358768_PRECISION,
> +				  dsibclk);
> +	dsiclk_nsk = (u32)div_u64((u64)1000000000 * TC358768_PRECISION, dsiclk);
> +	ui_nsk = dsiclk_nsk / 2;
> +	phy_delay_nsk = dsibclk_nsk + 2 * dsiclk_nsk;
> +	dev_dbg(priv->dev, "dsiclk_nsk: %u\n", dsiclk_nsk);
> +	dev_dbg(priv->dev, "ui_nsk: %u\n", ui_nsk);
> +	dev_dbg(priv->dev, "dsibclk_nsk: %u\n", dsibclk_nsk);
> +	dev_dbg(priv->dev, "phy_delay_nsk: %u\n", phy_delay_nsk);
> +
> +	/* LP11 > 100us for D-PHY Rx Init */
> +	val = tc358768_ns_to_cnt(100 * 1000, dsibclk_nsk) - 1;
> +	dev_dbg(priv->dev, "LINEINITCNT: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_LINEINITCNT, val);
> +
> +	/* LPTimeCnt > 50ns */
> +	val = tc358768_ns_to_cnt(50, dsibclk_nsk) - 1;
> +	lptxcnt = val;
> +	dev_dbg(priv->dev, "LPTXTIMECNT: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_LPTXTIMECNT, val);
> +
> +	/* 38ns < TCLK_PREPARE < 95ns */
> +	val = tc358768_ns_to_cnt(65, dsibclk_nsk) - 1;
> +	/* TCLK_PREPARE > 300ns */
> +	val2 = tc358768_ns_to_cnt(300 + tc358768_to_ns(3 * ui_nsk),
> +				  dsibclk_nsk);
> +	val |= (val2 - tc358768_to_ns(phy_delay_nsk - dsibclk_nsk)) << 8;
> +	dev_dbg(priv->dev, "TCLK_HEADERCNT: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_TCLK_HEADERCNT, val);
> +
> +	/* TCLK_TRAIL > 60ns + 3*UI */
> +	val = 60 + tc358768_to_ns(3 * ui_nsk);
> +	val = tc358768_ns_to_cnt(val, dsibclk_nsk) - 5;
> +	dev_dbg(priv->dev, "TCLK_TRAILCNT: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_TCLK_TRAILCNT, val);
> +
> +	/* 40ns + 4*UI < THS_PREPARE < 85ns + 6*UI */
> +	val = 50 + tc358768_to_ns(4 * ui_nsk);
> +	val = tc358768_ns_to_cnt(val, dsibclk_nsk) - 1;
> +	/* THS_ZERO > 145ns + 10*UI */
> +	val2 = tc358768_ns_to_cnt(145 - tc358768_to_ns(ui_nsk), dsibclk_nsk);
> +	val |= (val2 - tc358768_to_ns(phy_delay_nsk)) << 8;
> +	dev_dbg(priv->dev, "THS_HEADERCNT: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_THS_HEADERCNT, val);
> +
> +	/* TWAKEUP > 1ms in lptxcnt steps */
> +	val = tc358768_ns_to_cnt(1020000, dsibclk_nsk);
> +	val = val / (lptxcnt + 1) - 1;
> +	dev_dbg(priv->dev, "TWAKEUP: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_TWAKEUP, val);
> +
> +	/* TCLK_POSTCNT > 60ns + 52*UI */
> +	val = tc358768_ns_to_cnt(60 + tc358768_to_ns(52 * ui_nsk),
> +				 dsibclk_nsk) - 3;
> +	dev_dbg(priv->dev, "TCLK_POSTCNT: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_TCLK_POSTCNT, val);
> +
> +	/* 60ns + 4*UI < THS_PREPARE < 105ns + 12*UI */
> +	val = tc358768_ns_to_cnt(60 + tc358768_to_ns(15 * ui_nsk),
> +				 dsibclk_nsk) - 5;
> +	dev_dbg(priv->dev, "THS_TRAILCNT: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_THS_TRAILCNT, val);
> +
> +	val = BIT(0);
> +	for (i = 0; i < dsi_dev->lanes; i++)
> +		val |= BIT(i + 1);
> +	tc358768_write(priv, TC358768_HSTXVREGEN, val);
> +
> +	if (!(dsi_dev->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
> +		tc358768_write(priv, TC358768_TXOPTIONCNTRL, 0x1);
> +
> +	/* TXTAGOCNT[26:16] RXTASURECNT[10:0] */
> +	val = tc358768_to_ns((lptxcnt + 1) * dsibclk_nsk * 4);
> +	val = tc358768_ns_to_cnt(val, dsibclk_nsk) - 1;
> +	val2 = tc358768_ns_to_cnt(tc358768_to_ns((lptxcnt + 1) * dsibclk_nsk),
> +				  dsibclk_nsk) - 2;
> +	val |= val2 << 16;
> +	dev_dbg(priv->dev, "BTACNTRL1: 0x%x\n", val);
> +	tc358768_write(priv, TC358768_BTACNTRL1, val);
> +
> +	/* START[0] */
> +	tc358768_write(priv, TC358768_STARTCNTRL, 1);
> +
> +	/* Set event mode */
> +	tc358768_write(priv, TC358768_DSI_EVENT, 1);
> +
> +	/* vsw (+ vbp) */
> +	tc358768_write(priv, TC358768_DSI_VSW,
> +		       mode->vtotal - mode->vsync_start);
> +	/* vbp (not used in event mode) */
> +	tc358768_write(priv, TC358768_DSI_VBPR, 0);
> +	/* vact */
> +	tc358768_write(priv, TC358768_DSI_VACT, mode->vdisplay);
> +
> +	/* (hsw + hbp) * byteclk * ndl / pclk */
> +	val = (u32)div_u64((mode->htotal - mode->hsync_start) *
> +			   ((u64)priv->dsiclk / 4) * priv->dsi_lanes,
> +			   mode->clock * 1000);
> +	tc358768_write(priv, TC358768_DSI_HSW, val);
> +	/* hbp (not used in event mode) */
> +	tc358768_write(priv, TC358768_DSI_HBPR, 0);
> +	/* hact (bytes) */
> +	tc358768_write(priv, TC358768_DSI_HACT, hact);
> +
> +	/* VSYNC polarity */
> +	if (!(mode->flags & DRM_MODE_FLAG_NVSYNC))
> +		tc358768_update_bits(priv, TC358768_CONFCTL, BIT(5), BIT(5));
> +	/* HSYNC polarity */
> +	if (mode->flags & DRM_MODE_FLAG_PHSYNC)
> +		tc358768_update_bits(priv, TC358768_PP_MISC, BIT(0), BIT(0));
> +
> +	/* Start DSI Tx */
> +	tc358768_write(priv, TC358768_DSI_START, 0x1);
> +
> +	/* Configure DSI_Control register */
> +	val = (6 << 29) | (0x3 << 24); /* CLEAR, DSI_Control */
> +	val |= BIT(7) | BIT(5) | 0x3 << 1 | BIT(0);
> +	tc358768_write(priv, TC358768_DSI_CONFW, val);
> +
> +	val = (5 << 29) | (0x3 << 24); /* SET, DSI_Control */
> +	if (!(dsi_dev->mode_flags & MIPI_DSI_MODE_LPM))
> +		val |= BIT(7);
> +	if (!(dsi_dev->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
> +		val |= BIT(5);
> +	val |= (dsi_dev->lanes - 1) << 1;
> +	if (dsi_dev->mode_flags & MIPI_DSI_MODE_EOT_PACKET)
> +		val |= BIT(0);
> +	tc358768_write(priv, TC358768_DSI_CONFW, val);
> +
> +	val = (6 << 29) | (0x3 << 24); /* CLEAR, DSI_Control */
> +	val |= 0x8000; /* DSI mode */
> +	tc358768_write(priv, TC358768_DSI_CONFW, val);
> +
> +	/* clear FrmStop and RstPtr */
> +	tc358768_update_bits(priv, TC358768_PP_MISC, 0x3 << 14, 0);
> +
> +	/* set PP_en */
> +	tc358768_update_bits(priv, TC358768_CONFCTL, BIT(6), BIT(6));
> +
> +	ret = tc358768_clear_error(priv);
> +	if (ret) {
> +		dev_err(priv->dev, "Bridge enable failed: %d\n", ret);
> +		tc358768_bridge_disable(bridge);
> +	}
> +}
> +
> +static const struct drm_bridge_funcs tc358768_bridge_funcs = {
> +	.attach = tc358768_bridge_attach,
> +	.mode_valid = tc358768_bridge_mode_valid,
> +	.disable = tc358768_bridge_disable,
> +	.enable = tc358768_bridge_enable,
> +};
> +
> +static const struct drm_bridge_timings default_tc358768_timings = {
> +	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE
> +		 | DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE
> +		 | DRM_BUS_FLAG_DE_HIGH,
> +};
> +
> +static bool tc358768_is_reserved_reg(unsigned int reg)
> +{
> +	switch (reg) {
> +	case 0x114 ... 0x13f:
> +	case 0x200:
> +	case 0x20c:
> +	case 0x400 ... 0x408:
> +	case 0x41c ... 0x42f:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static bool tc358768_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	if (tc358768_is_reserved_reg(reg))
> +		return false;
> +
> +	switch (reg) {
> +	case TC358768_CHIPID:
> +	case TC358768_FIFOSTATUS:
> +	case TC358768_DSITXSTATUS ... (TC358768_DSITXSTATUS + 2):
> +	case TC358768_DSI_CONTROL ... (TC358768_DSI_INT_ENA + 2):
> +	case TC358768_DSICMD_RDFIFO ... (TC358768_DSI_ERR_HALT + 2):
> +		return false;
> +	default:
> +		return true;
> +	}
> +}
> +
> +static bool tc358768_readable_reg(struct device *dev, unsigned int reg)
> +{
> +	if (tc358768_is_reserved_reg(reg))
> +		return false;
> +
> +	switch (reg) {
> +	case TC358768_STARTCNTRL:
> +	case TC358768_DSI_CONFW ... (TC358768_DSI_CONFW + 2):
> +	case TC358768_DSI_INT_CLR ... (TC358768_DSI_INT_CLR + 2):
> +	case TC358768_DSI_START ... (TC358768_DSI_START + 2):
> +	case TC358768_DBG_DATA:
> +		return false;
> +	default:
> +		return true;
> +	}
> +}
> +
> +static const struct regmap_config tc358768_regmap_config = {
> +	.name = "tc358768",
> +	.reg_bits = 16,
> +	.val_bits = 16,
> +	.max_register = TC358768_DSI_HACT,
> +	.cache_type = REGCACHE_NONE,
> +	.writeable_reg = tc358768_writeable_reg,
> +	.readable_reg = tc358768_readable_reg,
> +	.reg_format_endian = REGMAP_ENDIAN_BIG,
> +	.val_format_endian = REGMAP_ENDIAN_BIG,
> +};
> +
> +static const struct i2c_device_id tc358768_i2c_ids[] = {
> +	{ "tc358768", 0 },
> +	{ "tc358778", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, tc358768_i2c_ids);
> +
> +static const struct of_device_id tc358768_of_ids[] = {
> +	{ .compatible = "toshiba,tc358768", },
> +	{ .compatible = "toshiba,tc358778", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, tc358768_of_ids);
> +
> +static int tc358768_get_regulators(struct tc358768_priv *priv)
> +{
> +	int i, ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(priv->supplies); ++i)
> +		priv->supplies[i].supply = tc358768_supplies[i];
> +
> +	ret = devm_regulator_bulk_get(priv->dev, ARRAY_SIZE(priv->supplies),
> +				      priv->supplies);
> +	if (ret < 0)
> +		dev_err(priv->dev, "failed to get regulators: %d\n", ret);
> +
> +	return ret;
> +}
> +
> +static int tc358768_i2c_probe(struct i2c_client *client,
> +			      const struct i2c_device_id *id)
> +{
> +	struct tc358768_priv *priv;
> +	struct device *dev = &client->dev;
> +	struct device_node *np = dev->of_node;
> +	int ret;
> +
> +	if (!np)
> +		return -ENODEV;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	dev_set_drvdata(dev, priv);
> +	priv->dev = dev;
> +
> +	ret = tc358768_get_regulators(priv);
> +	if (ret)
> +		return ret;
> +
> +	priv->refclk = devm_clk_get(dev, "refclk");
> +	if (IS_ERR(priv->refclk))
> +		return PTR_ERR(priv->refclk);
> +
> +	/*
> +	 * RESX is low active, to disable tc358768 initially (keep in reset)
> +	 * the gpio line must be LOW. This is the ASSERTED state of
> +	 * GPIO_ACTIVE_LOW (GPIOD_OUT_HIGH == ASSERTED).
> +	 */
> +	priv->reset_gpio  = devm_gpiod_get_optional(dev, "reset",
> +						    GPIOD_OUT_HIGH);
> +	if (IS_ERR(priv->reset_gpio))
> +		return PTR_ERR(priv->reset_gpio);
> +
> +	priv->regmap = devm_regmap_init_i2c(client, &tc358768_regmap_config);
> +	if (IS_ERR(priv->regmap)) {
> +		dev_err(dev, "Failed to init regmap\n");
> +		return PTR_ERR(priv->regmap);
> +	}
> +
> +	priv->dsi_host.dev = dev;
> +	priv->dsi_host.ops = &tc358768_dsi_host_ops;
> +
> +	priv->bridge.funcs = &tc358768_bridge_funcs;
> +	priv->bridge.timings = &default_tc358768_timings;
> +	priv->bridge.of_node = np;
> +
> +	i2c_set_clientdata(client, priv);
> +
> +	ret = mipi_dsi_host_register(&priv->dsi_host);
> +	if (ret)
> +		return ret;
> +
> +	return 0;


It could be replaced by:

    return mipi_dsi_host_register(&priv->dsi_host);

Matter of taste, up to you.


Overall the driver is in good shape, except hw_enable refcounting, which
I hope we will clarify quickly.


Regards

Andrzej


> +}
> +
> +static int tc358768_i2c_remove(struct i2c_client *client)
> +{
> +	struct tc358768_priv *priv = i2c_get_clientdata(client);
> +
> +	mipi_dsi_host_unregister(&priv->dsi_host);
> +
> +	return 0;
> +}
> +
> +static struct i2c_driver tc358768_driver = {
> +	.driver = {
> +		.name = "tc358768",
> +		.of_match_table = tc358768_of_ids,
> +	},
> +	.id_table = tc358768_i2c_ids,
> +	.probe = tc358768_i2c_probe,
> +	.remove	= tc358768_i2c_remove,
> +};
> +module_i2c_driver(tc358768_driver);
> +
> +MODULE_AUTHOR("Peter Ujfalusi <peter.ujfalusi@ti.com>");
> +MODULE_DESCRIPTION("TC358768AXBG/TC358778XBG DSI bridge");
> +MODULE_LICENSE("GPL v2");