[PATCH v2 6/8] drm/panel: add driver for samsung amb655x

[Dmitry Baryshkov]

On Sun, Jun 30, 2024 at 08:36:29PM GMT, Caleb Connolly wrote:
> This is a 1080x2400 120hz panel used on the OnePlus 8T. It uses DSC but
> with many non-standard DCS commands.
> 
> The only user of this panel (the OnePlus 8T) has a bug somewhere in the
> DSI stack whereby it isn't possible to properly initialize this panel
> after a reset. As a result, the reset GPIO is made optional so it can be
> left unused on that device.
> 
> Signed-off-by: Caleb Connolly <caleb at postmarketos.org>
> ---
>  MAINTAINERS                                   |   7 +
>  drivers/gpu/drm/panel/Kconfig                 |   9 +
>  drivers/gpu/drm/panel/Makefile                |   1 +
>  drivers/gpu/drm/panel/panel-samsung-amb655x.c | 399 ++++++++++++++++++++++++++
>  4 files changed, 416 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 807feae089c4..2b9cfbf92d7a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7142,8 +7142,15 @@ M:	Robert Chiras <robert.chiras at nxp.com>
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/display/panel/raydium,rm67191.yaml
>  F:	drivers/gpu/drm/panel/panel-raydium-rm67191.c
>  
> +DRM DRIVER FOR SAMSUNG AMB655X PANEL
> +M:	Caleb Connolly <caleb at postmarketos.org>
> +S:	Maintained
> +T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
> +F:	Documentation/devicetree/bindings/display/panel/samsung,amb655x.yaml
> +F:	drivers/gpu/drm/panel/panel-samsung-amb655x.c
> +
>  DRM DRIVER FOR SAMSUNG DB7430 PANELS
>  M:	Linus Walleij <linus.walleij at linaro.org>
>  S:	Maintained
>  T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index bf4eadfe21cb..7203d16ab20a 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -590,8 +590,17 @@ config DRM_PANEL_SAMSUNG_S6E88A0_AMS452EF01
>  	depends on OF
>  	select DRM_MIPI_DSI
>  	select VIDEOMODE_HELPERS
>  
> +config DRM_PANEL_SAMSUNG_AMB655X
> +	tristate "Samsung AMB655X DSI panel"
> +	depends on OF
> +	depends on DRM_MIPI_DSI
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	help
> +	  DRM panel driver for the Samsung AMB655X panel.
> +	  This panel has a resolution of 1080x2400 @ 60hz or 120Hz.
> +
>  config DRM_PANEL_SAMSUNG_ATNA33XC20
>  	tristate "Samsung ATNA33XC20 eDP panel"
>  	depends on OF
>  	depends on BACKLIGHT_CLASS_DEVICE
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 051b75b3df7b..be6d500a56a4 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -58,8 +58,9 @@ obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM67191) += panel-raydium-rm67191.o
>  obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM68200) += panel-raydium-rm68200.o
>  obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM692E5) += panel-raydium-rm692e5.o
>  obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM69380) += panel-raydium-rm69380.o
>  obj-$(CONFIG_DRM_PANEL_RONBO_RB070D30) += panel-ronbo-rb070d30.o
> +obj-$(CONFIG_DRM_PANEL_SAMSUNG_AMB655X) += panel-samsung-amb655x.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_ATNA33XC20) += panel-samsung-atna33xc20.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_DB7430) += panel-samsung-db7430.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6D16D0) += panel-samsung-s6d16d0.o


> +static int samsung_amb655x_prepare(struct drm_panel *panel)
> +{
> +	struct samsung_amb655x *ctx = to_samsung_amb655x(panel);
> +	struct device *dev = &ctx->dsi->dev;
> +	int ret;
> +
> +	/*
> +	 * During the first call to prepare, the regulators are already enabled
> +	 * since they're boot-on. Avoid enabling them twice so we keep the refcounts
> +	 * balanced.

I see your intent, but I don't think this is fully correct. If the
driver gets rebound, then it will perform one extra disable call. On the
next driver probe / enable / disable / remove cycle the driver will
perform one more, underflowing enable count. I think
regulator_init_complete_work_function should give the phone enough time
to boot the panel.

> +	 */
> +	if (!regulator_is_enabled(ctx->supplies[0].consumer)) {
> +		ret = regulator_bulk_enable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
> +		if (ret) {
> +			dev_err(dev, "Failed to enable regulators: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +

-- 
With best wishes
Dmitry