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

[Dmitry Baryshkov]

On Tue, 2 Jul 2024 at 12:43, Caleb Connolly <caleb at postmarketos.org> wrote:
>
>
>
> On 01/07/2024 22:32, Dmitry Baryshkov wrote:
> > 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.
>
> I do make an extra call to regulator_bulk_enable() in probe(), does that
> balance things out?

Hmm, I missed it. But if you have it, why not just have a single
regulator_bulk_enable() in pre_enable() like everybody else does?

> >
> >> +     */
> >> +    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