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Subject: Re: [PATCH v22 2/2] drm/bridge: Add I2C based driver for ps8640
 bridge
From:   Enric Balletbo i Serra <enric.balletbo@collabora.com>
To:     linux-kernel@vger.kernel.org
Cc:     Collabora Kernel ML <kernel@collabora.com>, matthias.bgg@gmail.com,
        drinkcat@chromium.org, hsinyi@chromium.org,
        Jitao Shi <jitao.shi@mediatek.com>,
        Daniel Kurtz <djkurtz@chromium.org>,
        Ulrich Hecht <uli@fpond.eu>,
        linux-arm-kernel@lists.infradead.org,
        Andrzej Hajda <a.hajda@samsung.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        dri-devel@lists.freedesktop.org,
        Neil Armstrong <narmstrong@baylibre.com>,
        linux-mediatek@lists.infradead.org,
        David Airlie <airlied@linux.ie>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Daniel Vetter <daniel@ffwll.ch>
References: <20191223143538.20327-1-enric.balletbo@collabora.com>
 <20191223143538.20327-3-enric.balletbo@collabora.com>
Message-ID: <7840b18d-39de-dd8a-eca8-6dc0cc23116c@collabora.com>
Date:   Mon, 23 Dec 2019 16:51:53 +0100
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Precedence: bulk

Hi Laurent,

On 23/12/19 15:35, Enric Balletbo i Serra wrote:
> From: Jitao Shi <jitao.shi@mediatek.com>
> 
> This patch adds drm_bridge driver for parade DSI to eDP bridge chip.
> 
> Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
> [uli: followed API changes, removed FW update feature]
> Signed-off-by: Ulrich Hecht <uli@fpond.eu>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> Tested-by: Hsin-Yi Wang <hsinyi@chromium.org>
> ---
> One of the reviews from Laurent was to use 'i2c_new_ancillary_device'. I
> didn't change this for two reasons.
> 1) It doesn't have a devm version, so the remove path is more simple
> using the devm_i2c_new_dummy_device family.
> 2) IIUC the ancillary function is useful when you want to retrieve the
> address from the firmware or DT, that's not really the case here, as we
> have a base address and fixed offset to the base address which I think
> is not configurable.
> 
> Let me know if you still think that I should use the ancillary call.
> 
> Changes in v23:
> - Merge mute/unmute functions into one (Nicolas Boichat)
> - Use enum for ENABLE/DISABLE instead of bool (Ezequiel Garcia)
> - Rename mute/unmute to vdo_control and fix error messages (Nicolas Boichat and Enric)
> - Add space between address and address parameter 'address%02x' (Nicolas Boichat)
> - Add Tested-by Hsin-Yi
> - Added me as author after the refactor
> 
> Changes in v22:
> - Remove sysfs attributes because are not really used (Enric Balletbo)
> - Use enum for address page offsets (Ezequiel Garcia)
> - Remove enable tracking (Enric Balletbo)
> - Use panel_bridge API (Laurent Pinchart)
> - Do not use kernel-doc format for non kernel-doc formatted commands (Enric Balletbo)
> - Remove verbose message for PAGE1_VSTART command (Ezequiel Garcia)
> - Use time_is_after_jiffies idiom (Ezequiel Garcia)
> - Remove unused macros (Ezequiel Garcia)
> - Fix weird alignment in dsi->mode_flags (Laurent Pinchart)
> - Use drm_of_find_panel_or_bridge helper (Laurent Pinchart)
> - Remove mode-sel-gpios as is not used (Laurent Pinchart)
> - Remove error messages to get gpios as the core will already report it (Enric Balletbo)
> - Remove redundant message getting the regulators (Laurent Pinchart)
> - Rename sleep-gpios to powerdown-gpios (Laurent Pinchart)
> - Use ARRAY_SIZE(ps_bridge->page) instead of MAX_DEV when possible (Laurent Pinchart)
> - Fix race with userspace accessing the sysfs attributes (Laurent Pinchart)
> - Remove id_table as is only used on DR platforms (Laurent Pinchart)
> - Convert to new i2c device probe() (Laurent Pinchart)
> - Use i2c_smbus_read/write helpers instead of open coding it (Laurent Pinchart)
> - Remove unnused global variables (Laurent Pinchart)
> - Remove unnused fields in ps8640 struct (Laurent Pinchart)
> - Remove commented-out headers (Laurent Pinchart)
> 
> Changes in v21:
>  - Use devm_i2c_new_dummy_device and fix build issue using deprecated i2c_new_dummy
>  - Fix build issue due missing drm_bridge.h
>  - Do not remove in ps8640_remove device managed resources
> 
> Changes in v19:
>  - fixed return value of ps8640_probe() when no panel is found
> 
> Changes in v18:
>  - followed DRM API changes
>  - use DEVICE_ATTR_RO()
>  - remove firmware update code
>  - add SPDX identifier
> 
> Changes in v17:
>  - remove some unused head files.
>  - add macros for ps8640 pages.
>  - remove ddc_i2c client
>  - add mipi_dsi_device_register_full
>  - remove the manufacturer from the name and i2c_device_id
> 
> Changes in v16:
>  - Disable ps8640 DSI MCS Function.
>  - Rename gpios name more clearly.
>  - Tune the ps8640 power on sequence.
> 
> Changes in v15:
>  - Drop drm_connector_(un)register calls from parade ps8640.
>    The main DRM driver mtk_drm_drv now calls
>    drm_connector_register_all() after drm_dev_register() in the
>    mtk_drm_bind() function. That function should iterate over all
>    connectors and call drm_connector_register() for each of them.
>    So, remove drm_connector_(un)register calls from parade ps8640.
> 
> Changes in v14:
>  - update copyright info.
>  - change bridge_to_ps8640 and connector_to_ps8640 to inline function.
>  - fix some coding style.
>  - use sizeof as array counter.
>  - use drm_get_edid when read edid.
>  - add mutex when firmware updating.
> 
> Changes in v13:
>  - add const on data, ps8640_write_bytes(struct i2c_client *client, const u8 *data, u16 data_len)
>  - fix PAGE2_SW_REST tyro.
>  - move the buf[3] init to entrance of the function.
> 
> Changes in v12:
>  - fix hw_chip_id build warning
> 
> Changes in v11:
>  - Remove depends on I2C, add DRM depends
>  - Reuse ps8640_write_bytes() in ps8640_write_byte()
>  - Use timer check for polling like the routines in <linux/iopoll.h>
>  - Fix no drm_connector_unregister/drm_connector_cleanup when ps8640_bridge_attach fail
>  - Check the ps8640 hardware id in ps8640_validate_firmware
>  - Remove fw_version check
>  - Move ps8640_validate_firmware before ps8640_enter_bl
>  - Add ddc_i2c unregister when probe fail and ps8640_remove
> 
>  drivers/gpu/drm/bridge/Kconfig         |  11 +
>  drivers/gpu/drm/bridge/Makefile        |   1 +
>  drivers/gpu/drm/bridge/parade-ps8640.c | 348 +++++++++++++++++++++++++
>  3 files changed, 360 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/parade-ps8640.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 4734f6993858..3e0a63011723 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -101,6 +101,17 @@ config DRM_PARADE_PS8622
>  	---help---
>  	  Parade eDP-LVDS bridge chip driver.
>  
> +config DRM_PARADE_PS8640
> +	tristate "Parade PS8640 MIPI DSI to eDP Converter"
> +	depends on OF
> +	select DRM_KMS_HELPER
> +	select DRM_MIPI_DSI
> +	select DRM_PANEL
> +	help
> +	  Choose this option if you have PS8640 for display
> +	  The PS8640 is a high-performance and low-power
> +	  MIPI DSI to eDP converter
> +
>  config DRM_SIL_SII8620
>  	tristate "Silicon Image SII8620 HDMI/MHL bridge"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 1c0c92667ac4..91490c595b38 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_DRM_LVDS_ENCODER) += lvds-encoder.o
>  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
>  obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
>  obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
> +obj-$(CONFIG_DRM_PARADE_PS8640) += parade-ps8640.o
>  obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o
>  obj-$(CONFIG_DRM_SII902X) += sii902x.o
>  obj-$(CONFIG_DRM_SII9234) += sii9234.o
> diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
> new file mode 100644
> index 000000000000..646ac649d175
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
> @@ -0,0 +1,348 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2016 MediaTek Inc.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of_graph.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>
> +
> +#define PAGE2_GPIO_H		0xa7
> +#define PS_GPIO9		BIT(1)
> +#define PAGE2_I2C_BYPASS	0xea
> +#define I2C_BYPASS_EN		0xd0
> +#define PAGE2_MCS_EN		0xf3
> +#define MCS_EN			BIT(0)
> +#define PAGE3_SET_ADD		0xfe
> +#define VDO_CTL_ADD		0x13
> +#define VDO_DIS			0x18
> +#define VDO_EN			0x1c
> +
> +/*
> + * PS8640 uses multiple addresses:
> + * page[0]: for DP control
> + * page[1]: for VIDEO Bridge
> + * page[2]: for control top
> + * page[3]: for DSI Link Control1
> + * page[4]: for MIPI Phy
> + * page[5]: for VPLL
> + * page[6]: for DSI Link Control2
> + * page[7]: for SPI ROM mapping
> + */
> +enum page_addr_offset {
> +	PAGE0_DP_CNTL = 0,
> +	PAGE1_VDO_BDG,
> +	PAGE2_TOP_CNTL,
> +	PAGE3_DSI_CNTL1,
> +	PAGE4_MIPI_PHY,
> +	PAGE5_VPLL,
> +	PAGE6_DSI_CNTL2,
> +	PAGE7_SPI_CNTL,
> +	MAX_DEVS
> +};
> +
> +enum ps8640_vdo_control {
> +	DISABLE = VDO_DIS,
> +	ENABLE = VDO_EN,
> +};
> +
> +struct ps8640 {
> +	struct drm_bridge bridge;
> +	struct drm_bridge *panel_bridge;
> +	struct mipi_dsi_device *dsi;
> +	struct i2c_client *page[MAX_DEVS];
> +	struct regulator_bulk_data supplies[2];
> +	struct gpio_desc *gpio_reset;
> +	struct gpio_desc *gpio_powerdown;
> +};
> +
> +static inline struct ps8640 *bridge_to_ps8640(struct drm_bridge *e)
> +{
> +	return container_of(e, struct ps8640, bridge);
> +}
> +
> +static int ps8640_bridge_vdo_control(struct ps8640 *ps_bridge,
> +				     const enum ps8640_vdo_control ctrl)
> +{
> +	struct i2c_client *client = ps_bridge->page[PAGE3_DSI_CNTL1];
> +	u8 vdo_ctrl_buf[] = { VDO_CTL_ADD, ctrl };
> +	int ret;
> +
> +	ret = i2c_smbus_write_i2c_block_data(client, PAGE3_SET_ADD,
> +					     sizeof(vdo_ctrl_buf),
> +					     vdo_ctrl_buf);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static void ps8640_pre_enable(struct drm_bridge *bridge)
> +{
> +	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> +	struct i2c_client *client = ps_bridge->page[PAGE2_TOP_CNTL];
> +	unsigned long timeout;
> +	int ret, status;
> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(ps_bridge->supplies),
> +				    ps_bridge->supplies);
> +	if (ret < 0) {
> +		DRM_ERROR("cannot enable regulators %d\n", ret);
> +		return;
> +	}
> +
> +	gpiod_set_value(ps_bridge->gpio_powerdown, 1);
> +	gpiod_set_value(ps_bridge->gpio_reset, 0);
> +	usleep_range(2000, 2500);
> +	gpiod_set_value(ps_bridge->gpio_reset, 1);
> +
> +	/*
> +	 * Wait for the ps8640 embedded MCU to be ready
> +	 * First wait 200ms and then check the MCU ready flag every 20ms
> +	 */
> +	msleep(200);
> +
> +	timeout = jiffies + msecs_to_jiffies(200) + 1;
> +
> +	while (time_is_after_jiffies(timeout)) {
> +		status = i2c_smbus_read_byte_data(client, PAGE2_GPIO_H);
> +		if (status < 0) {
> +			DRM_ERROR("failed read PAGE2_GPIO_H: %d\n", status);
> +			goto err_regulators_disable;
> +		}
> +		if ((status & PS_GPIO9) == PS_GPIO9)
> +			break;
> +
> +		msleep(20);
> +	}
> +
> +	msleep(50);
> +
> +	/*
> +	 * The Manufacturer Command Set (MCS) is a device dependent interface
> +	 * intended for factory programming of the display module default
> +	 * parameters. Once the display module is configured, the MCS shall be
> +	 * disabled by the manufacturer. Once disabled, all MCS commands are
> +	 * ignored by the display interface.
> +	 */
> +	status = i2c_smbus_read_byte_data(client, PAGE2_MCS_EN);
> +	if (status < 0) {
> +		DRM_ERROR("failed read PAGE2_MCS_EN: %d\n", status);
> +		goto err_regulators_disable;
> +	}
> +
> +	ret = i2c_smbus_write_byte_data(client, PAGE2_MCS_EN,
> +					status & ~MCS_EN);
> +	if (ret < 0) {
> +		DRM_ERROR("failed write PAGE2_MCS_EN: %d\n", ret);
> +		goto err_regulators_disable;
> +	}
> +
> +	ret = ps8640_bridge_vdo_control(ps_bridge, ENABLE);
> +	if (ret) {
> +		DRM_ERROR("failed to enable VDO: %d\n", ret);
> +		goto err_regulators_disable;
> +	}
> +
> +	/* Switch access edp panel's edid through i2c */
> +	ret = i2c_smbus_write_byte_data(client, PAGE2_I2C_BYPASS,
> +					I2C_BYPASS_EN);
> +	if (ret < 0) {
> +		DRM_ERROR("failed write PAGE2_I2C_BYPASS: %d\n", ret);
> +		goto err_regulators_disable;
> +	}
> +
> +	return;
> +
> +err_regulators_disable:
> +	regulator_bulk_disable(ARRAY_SIZE(ps_bridge->supplies),
> +			       ps_bridge->supplies);
> +}
> +
> +static void ps8640_post_disable(struct drm_bridge *bridge)
> +{
> +	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> +	int ret;
> +
> +	ret = ps8640_bridge_vdo_control(ps_bridge, DISABLE);
> +	if (ret < 0)
> +		DRM_ERROR("failed to disable VDO: %d\n", ret);
> +
> +	gpiod_set_value(ps_bridge->gpio_reset, 0);
> +	gpiod_set_value(ps_bridge->gpio_powerdown, 0);
> +	ret = regulator_bulk_disable(ARRAY_SIZE(ps_bridge->supplies),
> +				     ps_bridge->supplies);
> +	if (ret < 0)
> +		DRM_ERROR("cannot disable regulators %d\n", ret);
> +}
> +
> +int ps8640_bridge_attach(struct drm_bridge *bridge)
> +{
> +	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> +	struct device *dev = &ps_bridge->page[0]->dev;
> +	struct device_node *in_ep, *dsi_node;
> +	struct mipi_dsi_device *dsi;
> +	struct mipi_dsi_host *host;
> +	int ret;
> +	const struct mipi_dsi_device_info info = { .type = "ps8640",
> +						   .channel = 0,
> +						   .node = NULL,
> +						 };
> +	/* port@0 is ps8640 dsi input port */
> +	in_ep = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
> +	if (!in_ep)
> +		return -ENODEV;
> +
> +	dsi_node = of_graph_get_remote_port_parent(in_ep);
> +	of_node_put(in_ep);
> +	if (!dsi_node)
> +		return -ENODEV;
> +
> +	host = of_find_mipi_dsi_host_by_node(dsi_node);
> +	of_node_put(dsi_node);
> +	if (!host)
> +		return -ENODEV;
> +
> +	dsi = mipi_dsi_device_register_full(host, &info);
> +	if (IS_ERR(dsi)) {
> +		dev_err(dev, "failed to create dsi device\n");
> +		ret = PTR_ERR(dsi);
> +		return ret;
> +	}
> +
> +	ps_bridge->dsi = dsi;
> +
> +	dsi->host = host;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO |
> +			  MIPI_DSI_MODE_VIDEO_SYNC_PULSE;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->lanes = 4;
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret)
> +		goto err_dsi_attach;
> +
> +	/* Attach the panel-bridge to the dsi bridge */
> +	return drm_bridge_attach(bridge->encoder, ps_bridge->panel_bridge,
> +				 &ps_bridge->bridge);
> +
> +err_dsi_attach:
> +	mipi_dsi_device_unregister(dsi);
> +	return ret;
> +}
> +
> +static const struct drm_bridge_funcs ps8640_bridge_funcs = {
> +	.attach = ps8640_bridge_attach,
> +	.post_disable = ps8640_post_disable,
> +	.pre_enable = ps8640_pre_enable,
> +};
> +
> +static int ps8640_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct device_node *np = dev->of_node;
> +	struct ps8640 *ps_bridge;
> +	struct drm_panel *panel;
> +	int ret;
> +	u32 i;
> +
> +	ps_bridge = devm_kzalloc(dev, sizeof(*ps_bridge), GFP_KERNEL);
> +	if (!ps_bridge)
> +		return -ENOMEM;
> +
> +	/* port@1 is ps8640 output port */
> +	ret = drm_of_find_panel_or_bridge(np, 1, 0, &panel, NULL);
> +	if (ret < 0)
> +		return ret;
> +	if (!panel)
> +		return -ENODEV;
> +
> +	panel->connector_type = DRM_MODE_CONNECTOR_eDP;
> +
> +	ps_bridge->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
> +	if (IS_ERR(ps_bridge->panel_bridge))
> +		return PTR_ERR(ps_bridge->panel_bridge);
> +
> +	ps_bridge->supplies[0].supply = "vdd33";
> +	ps_bridge->supplies[1].supply = "vdd12";
> +	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ps_bridge->supplies),
> +				      ps_bridge->supplies);
> +	if (ret)
> +		return ret;
> +
> +	ps_bridge->gpio_powerdown = devm_gpiod_get(&client->dev, "powerdown",
> +						   GPIOD_OUT_LOW);
> +	if (IS_ERR(ps_bridge->gpio_powerdown))
> +		return PTR_ERR(ps_bridge->gpio_powerdown);
> +
> +	/*
> +	 * Request the reset pin low to avoid the bridge being
> +	 * initialized prematurely

Ezequiel made me realise that I didn't address one of your comments from the
beginning.

"The polarity is wrong in DT then. Requesting the GPIO low should
deassert reset, in drivers all GPIO descriptors should be handled as
active high. Same for the sleep GPIO."


I fixed my DT and I'll fix this in next version I send. I'll just wait a bit for
if I receive more feedback to no flood more the ML with these patches. Let me
know if you have more comments.

Thanks,
 Enric


> +	 */
> +	ps_bridge->gpio_reset = devm_gpiod_get(&client->dev, "reset",
> +					       GPIOD_OUT_LOW);
> +	if (IS_ERR(ps_bridge->gpio_reset))
> +		return PTR_ERR(ps_bridge->gpio_reset);
> +
> +	ps_bridge->bridge.funcs = &ps8640_bridge_funcs;
> +	ps_bridge->bridge.of_node = dev->of_node;
> +
> +	ps_bridge->page[PAGE0_DP_CNTL] = client;
> +
> +	for (i = 1; i < ARRAY_SIZE(ps_bridge->page); i++) {
> +		ps_bridge->page[i] = devm_i2c_new_dummy_device(&client->dev,
> +							     client->adapter,
> +							     client->addr + i);
> +		if (IS_ERR(ps_bridge->page[i])) {
> +			dev_err(dev, "failed i2c dummy device, address %02x\n",
> +				client->addr + i);
> +			return PTR_ERR(ps_bridge->page[i]);
> +		}
> +	}
> +
> +	i2c_set_clientdata(client, ps_bridge);
> +
> +	drm_bridge_add(&ps_bridge->bridge);
> +
> +	return 0;
> +}
> +
> +static int ps8640_remove(struct i2c_client *client)
> +{
> +	struct ps8640 *ps_bridge = i2c_get_clientdata(client);
> +
> +	drm_bridge_remove(&ps_bridge->bridge);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ps8640_match[] = {
> +	{ .compatible = "parade,ps8640" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ps8640_match);
> +
> +static struct i2c_driver ps8640_driver = {
> +	.probe_new = ps8640_probe,
> +	.remove = ps8640_remove,
> +	.driver = {
> +		.name = "ps8640",
> +		.of_match_table = ps8640_match,
> +	},
> +};
> +module_i2c_driver(ps8640_driver);
> +
> +MODULE_AUTHOR("Jitao Shi <jitao.shi@mediatek.com>");
> +MODULE_AUTHOR("CK Hu <ck.hu@mediatek.com>");
> +MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>");
> +MODULE_DESCRIPTION("PARADE ps8640 DSI-eDP converter driver");
> +MODULE_LICENSE("GPL v2");
>