drm/amd/display: check if ext_caps is valid in BL setup

LVDS connectors don't have extended backlight caps so check
if the pointer is valid before accessing it.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/5012
Fixes: 1454642960b0 ("drm/amd: Re-introduce property to control adaptive backlight modulation")
Cc: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 3f797396d7f4eb9bb6eded184bbc6f033628a6f6)
Cc: stable@vger.kernel.org

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 acc3d8dad4a38ec1429f77557c028ef27375cc79..2328c1aa0ead13e0d598b4e35290b7a8ffc819ce 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -5423,7 +5423,7 @@ static void setup_backlight_device(struct amdgpu_display_manager *dm,
        caps = &dm->backlight_caps[aconnector->bl_idx];
 
        /* Only offer ABM property when non-OLED and user didn't turn off by module parameter */
-       if (!caps->ext_caps->bits.oled && amdgpu_dm_abm_level < 0)
+       if (caps->ext_caps && !caps->ext_caps->bits.oled && amdgpu_dm_abm_level < 0)
                drm_object_attach_property(&aconnector->base.base,
                                           dm->adev->mode_info.abm_level_property,
                                           ABM_SYSFS_CONTROL);