[PATCH v2 3/3] drm/amd/display: Add support backlight quirks

[Thomas Weißschuh]

Not all platforms provide correct PWM backlight capabilities through ATIF.
Use the generic drm backlight quirk infrastructure to override the
capabilities where necessary.

Signed-off-by: Thomas Weißschuh <li...@weissschuh.net>
---
 drivers/gpu/drm/amd/amdgpu/Kconfig                |  1 +
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 28 +++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/Kconfig 
b/drivers/gpu/drm/amd/amdgpu/Kconfig
index 692fa7cf8fd2..4fe0e8e74bb9 100644
--- a/drivers/gpu/drm/amd/amdgpu/Kconfig
+++ b/drivers/gpu/drm/amd/amdgpu/Kconfig
@@ -25,6 +25,7 @@ config DRM_AMDGPU
        select DRM_BUDDY
        select DRM_SUBALLOC_HELPER
        select DRM_EXEC
+       select DRM_PANEL_BACKLIGHT_QUIRKS
        # amdgpu depends on ACPI_VIDEO when ACPI is enabled, for select to work
        # ACPI_VIDEO's dependencies must also be selected.
        select INPUT if ACPI
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 60404385d4d0..2d8a6d875170 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -93,6 +93,7 @@
 #include <drm/drm_fourcc.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_eld.h>
+#include <drm/drm_utils.h>
 #include <drm/drm_vblank.h>
 #include <drm/drm_audio_component.h>
 #include <drm/drm_gem_atomic_helper.h>
@@ -3329,6 +3330,31 @@ static struct drm_mode_config_helper_funcs 
amdgpu_dm_mode_config_helperfuncs = {
        .atomic_commit_setup = drm_dp_mst_atomic_setup_commit,
 };
 
+static void amdgpu_dm_apply_backlight_quirks(struct amdgpu_dm_connector 
*aconnector,
+                                            struct amdgpu_dm_backlight_caps 
*caps)
+{
+       const struct drm_panel_backlight_quirk *quirk;
+       const struct drm_edid *edid;
+
+       edid = drm_edid_alloc(aconnector->edid, EDID_LENGTH * 
(aconnector->edid->extensions + 1));
+       if (!edid)
+               return;
+
+       quirk = drm_get_panel_backlight_quirk(edid);
+
+       drm_edid_free(edid);
+
+       if (!quirk)
+               return;
+
+       if (quirk->overrides.pwm_min_brightness &&
+           caps->min_input_signal != quirk->pwm_min_brightness) {
+               drm_info(aconnector->base.dev,
+                        "Quirk: backlight min_input_signal=%d\n", 
quirk->pwm_min_brightness);
+               caps->min_input_signal = quirk->pwm_min_brightness;
+       }
+}
+
 static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
 {
        struct amdgpu_dm_backlight_caps *caps;
@@ -3369,6 +3395,8 @@ static void update_connector_ext_caps(struct 
amdgpu_dm_connector *aconnector)
                caps->aux_min_input_signal = 0;
                caps->aux_max_input_signal = 512;
        }
+
+       amdgpu_dm_apply_backlight_quirks(aconnector, caps);
 }
 
 void amdgpu_dm_update_connector_after_detect(

-- 
2.45.2