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 <[email protected]>
---
  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 <[email protected]>
  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 <[email protected]>
+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 <[email protected]>
  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?

+        */
+       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;
+               }
+       }
+

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