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

Jie Gan
2026-04-12T01:10:06Z

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");
>