Message-ID: <7b165177-083d-4940-89d0-d81a163d7c1f@linaro.org>
Date: Wed, 29 Oct 2025 22:00:00 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Kaustabh Chakraborty <kauschluss@...root.org>,
 Jessica Zhang <quic_jesszhan@...cinc.com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Jessica Zhang <jessica.zhang@....qualcomm.com>
Cc: dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v5 2/2] drm: panel: add support for Synaptics TDDI
 series DSI panels

On 10/9/25 18:22, Kaustabh Chakraborty wrote:
> Synaptics TDDI (Touch/Display Integration) panels utilize a single chip
> for display and touch controllers. Implement a simple device driver for
> such panels, along with its built-in LED backlight controller, and add
> support for TD4101 and TD4300 panels in the driver.
> 
> Signed-off-by: Kaustabh Chakraborty <kauschluss@...root.org>
> ---
>   drivers/gpu/drm/panel/Kconfig                |  11 ++
>   drivers/gpu/drm/panel/Makefile               |   1 +
>   drivers/gpu/drm/panel/panel-synaptics-tddi.c | 276 +++++++++++++++++++++++++++
>   3 files changed, 288 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 407c5f6a268b2ec66e5d0eddae26b3368e4cb2cb..98708979ab45281628620bbe803fe8b597eb812d 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -1045,6 +1045,17 @@ config DRM_PANEL_SYNAPTICS_R63353
>   	  Say Y if you want to enable support for panels based on the
>   	  Synaptics R63353 controller.
>   
> +config DRM_PANEL_SYNAPTICS_TDDI
> +	tristate "Synaptics TDDI display panels"
> +	depends on OF
> +	depends on DRM_MIPI_DSI
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	help
> +	  Say Y if you want to enable support for the Synaptics TDDI display
> +	  panels. There are multiple MIPI DSI panels manufactured under the TDDI
> +	  namesake, with varying resolutions and data lanes. They also have a
> +	  built-in LED backlight and a touch controller.
> +
>   config DRM_PANEL_TDO_TL070WSH30
>   	tristate "TDO TL070WSH30 DSI panel"
>   	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 3615a761b44f9de0b4a653be157d8e0bcbc8f6b7..2535e1c9df76451d1c66d7d211ac9bfbf18dc80e 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -100,6 +100,7 @@ obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7703) += panel-sitronix-st7703.o
>   obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7789V) += panel-sitronix-st7789v.o
>   obj-$(CONFIG_DRM_PANEL_SUMMIT) += panel-summit.o
>   obj-$(CONFIG_DRM_PANEL_SYNAPTICS_R63353) += panel-synaptics-r63353.o
> +obj-$(CONFIG_DRM_PANEL_SYNAPTICS_TDDI) += panel-synaptics-tddi.o
>   obj-$(CONFIG_DRM_PANEL_SONY_ACX565AKM) += panel-sony-acx565akm.o
>   obj-$(CONFIG_DRM_PANEL_SONY_TD4353_JDI) += panel-sony-td4353-jdi.o
>   obj-$(CONFIG_DRM_PANEL_SONY_TULIP_TRULY_NT35521) += panel-sony-tulip-truly-nt35521.o
> diff --git a/drivers/gpu/drm/panel/panel-synaptics-tddi.c b/drivers/gpu/drm/panel/panel-synaptics-tddi.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..a4b3cbdebb6ca4062c02c6e7ac184f3ec245926a
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-synaptics-tddi.c
> @@ -0,0 +1,276 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Synaptics TDDI display panel driver.
> + *
> + * Copyright (C) 2025 Kaustabh Chakraborty <kauschluss@...root.org>
> + */
> +
> +#include <linux/backlight.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +
> +#include <video/mipi_display.h>
> +
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_probe_helper.h>
> +
> +struct tddi_panel_data {
> +	u8 lanes;
> +	/* wait timings for panel enable */
> +	u8 delay_ms_sleep_exit;
> +	u8 delay_ms_display_on;
> +	/* wait timings for panel disable */
> +	u8 delay_ms_display_off;
> +	u8 delay_ms_sleep_enter;
> +};
> +
> +struct tddi_ctx {
> +	struct drm_panel panel;
> +	struct mipi_dsi_device *dsi;
> +	struct drm_display_mode mode;
> +	struct backlight_device *backlight;
> +	const struct tddi_panel_data *data;
> +	struct regulator_bulk_data *supplies;
> +	struct gpio_desc *reset_gpio;
> +	struct gpio_desc *backlight_gpio;
> +};
> +
> +static const struct regulator_bulk_data tddi_supplies[] = {
> +	{ .supply = "vio" },
> +	{ .supply = "vsn" },
> +	{ .supply = "vsp" },
> +};
> +
> +static inline struct tddi_ctx *to_tddi_ctx(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct tddi_ctx, panel);
> +}
> +
> +static int tddi_update_status(struct backlight_device *backlight)
> +{
> +	struct tddi_ctx *ctx = bl_get_data(backlight);
> +	struct mipi_dsi_multi_context dsi = { .dsi = ctx->dsi };
> +	u8 brightness = backlight_get_brightness(backlight);
> +
> +	if (!ctx->panel.enabled)
> +		return 0;
> +
> +	mipi_dsi_dcs_set_display_brightness_multi(&dsi, brightness);
> +
> +	return dsi.accum_err;
> +}
> +
> +static int tddi_prepare(struct drm_panel *panel)
> +{
> +	struct tddi_ctx *ctx = to_tddi_ctx(panel);
> +	struct device *dev = &ctx->dsi->dev;
> +	int ret;
> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(tddi_supplies), ctx->supplies);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to enable regulators: %d\n", ret);
> +		return ret;
> +	}
> +
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> +	usleep_range(5000, 6000);
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> +	usleep_range(5000, 6000);
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> +	usleep_range(10000, 11000);
> +
> +	gpiod_set_value_cansleep(ctx->backlight_gpio, 0);
> +	usleep_range(5000, 6000);
> +
> +	return 0;
> +}
> +
> +static int tddi_unprepare(struct drm_panel *panel)
> +{
> +	struct tddi_ctx *ctx = to_tddi_ctx(panel);
> +
> +	gpiod_set_value_cansleep(ctx->backlight_gpio, 1);
> +	usleep_range(5000, 6000);
> +
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> +	usleep_range(5000, 6000);
> +
> +	regulator_bulk_disable(ARRAY_SIZE(tddi_supplies), ctx->supplies);
> +
> +	return 0;
> +}
> +
> +static int tddi_enable(struct drm_panel *panel)
> +{
> +	struct tddi_ctx *ctx = to_tddi_ctx(panel);
> +	struct mipi_dsi_multi_context dsi = { .dsi = ctx->dsi };
> +	u8 brightness = ctx->backlight->props.brightness;
> +
> +	mipi_dsi_dcs_write_seq_multi(&dsi, MIPI_DCS_WRITE_POWER_SAVE, 0x00);
> +	mipi_dsi_dcs_write_seq_multi(&dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY, 0x0c);
> +
> +	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi);
> +	mipi_dsi_msleep(&dsi, ctx->data->delay_ms_sleep_exit);
> +
> +	/* sync the panel with the backlight's brightness level */
> +	mipi_dsi_dcs_set_display_brightness_multi(&dsi, brightness);
> +
> +	mipi_dsi_dcs_set_display_on_multi(&dsi);
> +	mipi_dsi_msleep(&dsi, ctx->data->delay_ms_display_on);
> +
> +	return dsi.accum_err;
> +};
> +
> +static int tddi_disable(struct drm_panel *panel)
> +{
> +	struct tddi_ctx *ctx = to_tddi_ctx(panel);
> +	struct mipi_dsi_multi_context dsi = { .dsi = ctx->dsi };
> +
> +	mipi_dsi_dcs_set_display_off_multi(&dsi);
> +	mipi_dsi_msleep(&dsi, ctx->data->delay_ms_display_off);
> +
> +	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi);
> +	mipi_dsi_msleep(&dsi, ctx->data->delay_ms_sleep_enter);
> +
> +	return dsi.accum_err;
> +}
> +
> +static int tddi_get_modes(struct drm_panel *panel,
> +			  struct drm_connector *connector)
> +{
> +	struct tddi_ctx *ctx = to_tddi_ctx(panel);
> +
> +	return drm_connector_helper_get_modes_fixed(connector, &ctx->mode);
> +}
> +
> +static const struct backlight_ops tddi_bl_ops = {
> +	.update_status = tddi_update_status,
> +};
> +
> +static const struct backlight_properties tddi_bl_props = {
> +	.type = BACKLIGHT_PLATFORM,
> +	.brightness = 255,
> +	.max_brightness = 255,
> +};
> +
> +static const struct drm_panel_funcs tddi_drm_panel_funcs = {
> +	.prepare = tddi_prepare,
> +	.unprepare = tddi_unprepare,
> +	.enable = tddi_enable,
> +	.disable = tddi_disable,
> +	.get_modes = tddi_get_modes,
> +};
> +
> +static int tddi_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct tddi_ctx *ctx;
> +	int ret;
> +
> +	ctx = devm_drm_panel_alloc(dev, struct tddi_ctx, panel,
> +				   &tddi_drm_panel_funcs, DRM_MODE_CONNECTOR_DSI);
> +	if (IS_ERR(ctx))
> +		return PTR_ERR(ctx);
> +
> +	ctx->data = of_device_get_match_data(dev);
> +
> +	ctx->dsi = dsi;
> +	mipi_dsi_set_drvdata(dsi, ctx);
> +
> +	ret = devm_regulator_bulk_get_const(dev, ARRAY_SIZE(tddi_supplies),
> +					    tddi_supplies, &ctx->supplies);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "failed to get regulators\n");
> +
> +	ctx->backlight_gpio = devm_gpiod_get_optional(dev, "backlight", GPIOD_ASIS);
> +	if (IS_ERR(ctx->backlight_gpio))
> +		return dev_err_probe(dev, PTR_ERR(ctx->backlight_gpio),
> +				     "failed to get backlight-gpios\n");
> +
> +	ctx->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_ASIS);
> +	if (IS_ERR(ctx->reset_gpio))
> +		return dev_err_probe(dev, PTR_ERR(ctx->reset_gpio),
> +				     "failed to get reset-gpios\n");
> +
> +	ret = of_get_drm_panel_display_mode(dev->of_node, &ctx->mode, NULL);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "failed to get panel timings\n");
> +
> +	ctx->backlight = devm_backlight_device_register(dev, dev_name(dev), dev,
> +							ctx, &tddi_bl_ops,
> +							&tddi_bl_props);
> +	if (IS_ERR(ctx->backlight))
> +		return dev_err_probe(dev, PTR_ERR(ctx->backlight),
> +				     "failed to register backlight device");
> +
> +	dsi->lanes = ctx->data->lanes;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
> +			  MIPI_DSI_MODE_VIDEO_NO_HFP;
> +
> +	ctx->panel.prepare_prev_first = true;
> +	drm_panel_add(&ctx->panel);
> +
> +	ret = devm_mipi_dsi_attach(dev, dsi);
> +	if (ret < 0) {
> +		drm_panel_remove(&ctx->panel);
> +		return dev_err_probe(dev, ret, "failed to attach to DSI host\n");
> +	}
> +
> +	return 0;
> +}
> +
> +static void tddi_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct tddi_ctx *ctx = mipi_dsi_get_drvdata(dsi);
> +
> +	drm_panel_remove(&ctx->panel);
> +}
> +
> +static const struct tddi_panel_data td4101_panel_data = {
> +	.lanes = 2,
> +	/* wait timings for panel enable */
> +	.delay_ms_sleep_exit = 100,
> +	.delay_ms_display_on = 0,
> +	/* wait timings for panel disable */
> +	.delay_ms_display_off = 20,
> +	.delay_ms_sleep_enter = 90,
> +};
> +
> +static const struct tddi_panel_data td4300_panel_data = {
> +	.lanes = 4,
> +	/* wait timings for panel enable */
> +	.delay_ms_sleep_exit = 100,
> +	.delay_ms_display_on = 0,
> +	/* wait timings for panel disable */
> +	.delay_ms_display_off = 0,
> +	.delay_ms_sleep_enter = 0,
> +};
> +
> +static const struct of_device_id tddi_of_device_id[] = {
> +	{
> +		.compatible = "syna,td4101-panel",
> +		.data = &td4101_panel_data,
> +	}, {
> +		.compatible = "syna,td4300-panel",
> +		.data = &td4300_panel_data,
> +	}, { }
> +};
> +MODULE_DEVICE_TABLE(of, tddi_of_device_id);
> +
> +static struct mipi_dsi_driver tddi_dsi_driver = {
> +	.probe = tddi_probe,
> +	.remove = tddi_remove,
> +	.driver = {
> +		.name = "panel-synaptics-tddi",
> +		.of_match_table = tddi_of_device_id,
> +	},
> +};
> +module_mipi_dsi_driver(tddi_dsi_driver);
> +
> +MODULE_AUTHOR("Kaustabh Chakraborty <kauschluss@...root.org>");
> +MODULE_DESCRIPTION("Synaptics TDDI Display Panel Driver");
> +MODULE_LICENSE("GPL");
> 

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>

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