drm/amd/display/amdgpu_dm: Fix backlight_device_register() error handling

backlight_device_register() returns an ERR_PTR on error, but other code
such as amdgpu_dm_connector_destroy() assumes dm->backlight_dev[i] is NULL
if no backlight is registered.

Clear dm->backlight_dev[i] on registration failure, to avoid other code
trying to deref an ERR_PTR pointer.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 eeaeca8b51f4d49ccfe9ec58a5ba18338c5d3ff2..1c69353defb583f15090e37119a6999045df2afc 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4218,9 +4218,10 @@ amdgpu_dm_register_backlight_device(struct amdgpu_display_manager *dm)
                                                                       &amdgpu_dm_backlight_ops,
                                                                       &props);
 
-       if (IS_ERR(dm->backlight_dev[dm->num_of_edps]))
+       if (IS_ERR(dm->backlight_dev[dm->num_of_edps])) {
                DRM_ERROR("DM: Backlight registration failed!\n");
-       else
+               dm->backlight_dev[dm->num_of_edps] = NULL;
+       } else
                DRM_DEBUG_DRIVER("DM: Registered Backlight device: %s\n", bl_name);
 }