Re: [PATCH v2 19/21] drm/panel: add driver for Waveshare 8.8" DSI TOUCH-A panel

[Jie Gan <jie.gan@oss.qualcomm.com>]

On 4/11/2026 8:10 PM, Dmitry Baryshkov wrote:
> Add driver for the panel found on Waveshare 8.8" DSI TOUCH-A kit. It
> uses ota7290b IC as a controller.
> 
> Reviewed-by: Linus Walleij <linusw@kernel.org>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> ---
>   drivers/gpu/drm/panel/Kconfig                    |  12 ++
>   drivers/gpu/drm/panel/Makefile                   |   1 +
>   drivers/gpu/drm/panel/panel-focaltech-ota7290b.c | 208 +++++++++++++++++++++++
>   3 files changed, 221 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index ba527b4d7737..979109c27b9b 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -144,6 +144,18 @@ config DRM_PANEL_FEIYANG_FY07024DI26A30D
>   	  Say Y if you want to enable support for panels based on the
>   	  Feiyang FY07024DI26A30-D MIPI-DSI interface.
>   
> +config DRM_PANEL_FOCALTECH_OTA7290B
> +	tristate "Focaltech OTA7290B"
> +	depends on DRM_MIPI_DSI
> +	depends on I2C
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	select DRM_KMS_HELPER
> +	help
> +	  Enable support for panels using OTA7290B as a controller (for
> +	  example, Waveshare 12.3" DSI TOUCH-A panel). Say Y here if you want
> +	  to enable support for this panel. To compile this driver as a module,
> +	  choose M here.
> +
>   config DRM_PANEL_DSI_CM
>   	tristate "Generic DSI command mode panels"
>   	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index a4291dc3905b..0d694acbfbb6 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_DRM_PANEL_EBBG_FT8719) += panel-ebbg-ft8719.o
>   obj-$(CONFIG_DRM_PANEL_ELIDA_KD35T133) += panel-elida-kd35t133.o
>   obj-$(CONFIG_DRM_PANEL_FEIXIN_K101_IM2BA02) += panel-feixin-k101-im2ba02.o
>   obj-$(CONFIG_DRM_PANEL_FEIYANG_FY07024DI26A30D) += panel-feiyang-fy07024di26a30d.o
> +obj-$(CONFIG_DRM_PANEL_FOCALTECH_OTA7290B) += panel-focaltech-ota7290b.o
>   obj-$(CONFIG_DRM_PANEL_HIMAX_HX8279) += panel-himax-hx8279.o
>   obj-$(CONFIG_DRM_PANEL_HIMAX_HX83102) += panel-himax-hx83102.o
>   obj-$(CONFIG_DRM_PANEL_HIMAX_HX83112A) += panel-himax-hx83112a.o
> diff --git a/drivers/gpu/drm/panel/panel-focaltech-ota7290b.c b/drivers/gpu/drm/panel/panel-focaltech-ota7290b.c
> new file mode 100644
> index 000000000000..991d6a4caf17
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-focaltech-ota7290b.c
> @@ -0,0 +1,208 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2024 Waveshare International Limited
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_probe_helper.h>
> +
> +struct ota7290b {
> +	struct drm_panel panel;
> +	struct mipi_dsi_device *dsi;
> +
> +	struct regulator *power;
> +	struct gpio_desc *reset;
> +	struct regulator *avdd;
> +	struct regulator *iovcc;
> +
> +	enum drm_panel_orientation orientation;
> +};
> +
> +static inline struct ota7290b *panel_to_ota(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct ota7290b, panel);
> +}
> +
> +static int ota7290b_prepare(struct drm_panel *panel)
> +{
> +	struct ota7290b *ctx = panel_to_ota(panel);
> +	struct mipi_dsi_multi_context dsi_ctx = { .dsi = ctx->dsi };
> +	int ret;
> +
> +	if (ctx->iovcc) {
> +		ret = regulator_enable(ctx->iovcc);
> +		if (ret)
> +			dev_err(panel->dev, "failed to enable IO regulator: %d\n", ret);
> +	}
> +
> +	if (ctx->avdd) {
> +		ret = regulator_enable(ctx->avdd);
> +		if (ret)
> +			dev_err(panel->dev, "failed to enable AVDD regulator: %d\n", ret);
> +	}
> +
> +	if (ctx->reset) {
> +		gpiod_set_value_cansleep(ctx->reset, 0);
> +		msleep(60);
> +		gpiod_set_value_cansleep(ctx->reset, 1);
> +		msleep(60);
> +		gpiod_set_value_cansleep(ctx->reset, 0);
> +		msleep(60);
> +	}
> +
> +	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
> +	mipi_dsi_msleep(&dsi_ctx, 120);
> +	mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
> +	mipi_dsi_msleep(&dsi_ctx, 50);
> +
> +	if (dsi_ctx.accum_err < 0)
> +		dev_err(panel->dev, "failed to init panel: %d\n", ret);

better to check dsi_ctx.accum_err instead ret here?

dev_err(panel->dev, "failed to init panel: %d\n", dsi_ctx.accum_err);

Thanks,
Jie

> +
> +	return dsi_ctx.accum_err;
> +}
> +
> +static int ota7290b_unprepare(struct drm_panel *panel)
> +{
> +	struct ota7290b *ctx = panel_to_ota(panel);
> +	struct mipi_dsi_multi_context dsi_ctx = { .dsi = ctx->dsi };
> +
> +	mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
> +	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
> +
> +	if (ctx->reset) {
> +		gpiod_set_value_cansleep(ctx->reset, 1);
> +		msleep(5);
> +	}
> +
> +	if (ctx->avdd)
> +		regulator_disable(ctx->avdd);
> +
> +	if (ctx->iovcc)
> +		regulator_disable(ctx->iovcc);
> +
> +	return 0;
> +}
> +
> +static const struct drm_display_mode waveshare_dsi_touch_8_8_a_mode = {
> +	.clock = 75000,
> +
> +	.hdisplay = 480,
> +	.hsync_start = 480 + 50,
> +	.hsync_end = 480 + 50 + 50,
> +	.htotal = 480 + 50 + 50 + 50,
> +
> +	.vdisplay = 1920,
> +	.vsync_start = 1920 + 20,
> +	.vsync_end = 1920 + 20 + 20,
> +	.vtotal = 1920 + 20 + 20 + 20,
> +
> +	.width_mm = 68,
> +	.height_mm = 219,
> +	.type = DRM_MODE_TYPE_DRIVER,
> +};
> +
> +static int ota7290b_get_modes(struct drm_panel *panel,
> +			      struct drm_connector *connector)
> +{
> +	return drm_connector_helper_get_modes_fixed(connector, &waveshare_dsi_touch_8_8_a_mode);
> +}
> +
> +static enum drm_panel_orientation ota7290b_get_orientation(struct drm_panel *panel)
> +{
> +	struct ota7290b *ctx = panel_to_ota(panel);
> +
> +	return ctx->orientation;
> +}
> +
> +static const struct drm_panel_funcs ota7290b_funcs = {
> +	.prepare = ota7290b_prepare,
> +	.unprepare = ota7290b_unprepare,
> +	.get_modes = ota7290b_get_modes,
> +	.get_orientation = ota7290b_get_orientation,
> +};
> +
> +static int ota7290b_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct ota7290b *ctx;
> +	int ret;
> +
> +	ctx = devm_drm_panel_alloc(&dsi->dev, struct ota7290b, panel,
> +				   &ota7290b_funcs,
> +				   DRM_MODE_CONNECTOR_DSI);
> +	if (!ctx)
> +		return -ENOMEM;
> +	mipi_dsi_set_drvdata(dsi, ctx);
> +	ctx->dsi = dsi;
> +
> +	ctx->reset = devm_gpiod_get_optional(&dsi->dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(ctx->reset))
> +		return dev_err_probe(&dsi->dev, PTR_ERR(ctx->reset),
> +				     "Couldn't get our reset GPIO\n");
> +
> +	ctx->iovcc = devm_regulator_get_optional(&dsi->dev, "iovcc");
> +	if (IS_ERR(ctx->iovcc))
> +		return dev_err_probe(&dsi->dev, PTR_ERR(ctx->iovcc),
> +					"Couldn't get our iovcc supply\n");
> +
> +	ctx->avdd = devm_regulator_get_optional(&dsi->dev, "avdd");
> +	if (IS_ERR(ctx->avdd))
> +		return dev_err_probe(&dsi->dev, PTR_ERR(ctx->avdd),
> +					"Couldn't get our avdd supply\n");
> +
> +	ret = of_drm_get_panel_orientation(
> +			dsi->dev.of_node, &ctx->orientation);
> +	if (ret) {
> +		dev_err(&dsi->dev, "%pOF: failed to get orientation: %d\n",
> +			dsi->dev.of_node, ret);
> +		return ret;
> +	}
> +
> +	ret = drm_panel_of_backlight(&ctx->panel);
> +	if (ret)
> +		return ret;
> +
> +	ctx->panel.prepare_prev_first = true;
> +
> +	ret = devm_drm_panel_add(&dsi->dev, &ctx->panel);
> +	if (ret)
> +		return ret;
> +
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_HSE |
> +		MIPI_DSI_MODE_LPM | MIPI_DSI_CLOCK_NON_CONTINUOUS,
> +	dsi->format = MIPI_DSI_FMT_RGB888,
> +	dsi->lanes = 2;
> +
> +	return devm_mipi_dsi_attach(&dsi->dev, dsi);
> +}
> +
> +static const struct of_device_id ota7290b_of_match[] = {
> +	{ .compatible = "waveshare,8.8-dsi-touch-a", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, ota7290b_of_match);
> +
> +static struct mipi_dsi_driver ota7290b_driver = {
> +	.probe		= ota7290b_probe,
> +	.driver = {
> +		.name		= "focaltech-ota7290b",
> +		.of_match_table	= ota7290b_of_match,
> +	},
> +};
> +module_mipi_dsi_driver(ota7290b_driver);
> +
> +MODULE_DESCRIPTION("Panel driver for Focaltech OTA7290B panels");
> +MODULE_LICENSE("GPL");
>