Revert "drm/amd/display: Only restore backlight after amdgpu_dm_init or dm_resume"

This fix regressed the original issue that commit 7875afa
("drm/amd/display: Fix brightness level not retained over reboot") solved,
so revert it until a different approach to solve the regression that
it caused with AMD_PRIVATE_COLOR is found.

Fixes: a490c8d ("drm/amd/display: Only restore backlight after amdgpu_dm_init or dm_resume")
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4620
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: matte-schwartz

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -2085,8 +2085,6 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 
 	dc_hardware_init(adev->dm.dc);
 
-	adev->dm.restore_backlight = true;
-
 	adev->dm.hpd_rx_offload_wq = hpd_rx_irq_create_workqueue(adev);
 	if (!adev->dm.hpd_rx_offload_wq) {
 		drm_err(adev_to_drm(adev), "failed to create hpd rx offload workqueue.\n");
@@ -3442,7 +3440,6 @@ static int dm_resume(struct amdgpu_ip_block *ip_block)
 		dc_set_power_state(dm->dc, DC_ACPI_CM_POWER_STATE_D0);
 
 		dc_resume(dm->dc);
-		adev->dm.restore_backlight = true;
 
 		amdgpu_dm_irq_resume_early(adev);
 
@@ -9969,6 +9966,7 @@ static void amdgpu_dm_commit_streams(struct drm_atomic_state *state,
 	bool mode_set_reset_required = false;
 	u32 i;
 	struct dc_commit_streams_params params = {dc_state->streams, dc_state->stream_count};
+	bool set_backlight_level = false;
 
 	/* Disable writeback */
 	for_each_old_connector_in_state(state, connector, old_con_state, i) {
@@ -10088,6 +10086,7 @@ static void amdgpu_dm_commit_streams(struct drm_atomic_state *state,
 			acrtc->hw_mode = new_crtc_state->mode;
 			crtc->hwmode = new_crtc_state->mode;
 			mode_set_reset_required = true;
+			set_backlight_level = true;
 		} else if (modereset_required(new_crtc_state)) {
 			drm_dbg_atomic(dev,
 				       "Atomic commit: RESET. crtc id %d:[%p]\n",
@@ -10144,16 +10143,13 @@ static void amdgpu_dm_commit_streams(struct drm_atomic_state *state,
 	 * to fix a flicker issue.
 	 * It will cause the dm->actual_brightness is not the current panel brightness
 	 * level. (the dm->brightness is the correct panel level)
-	 * So we set the backlight level with dm->brightness value after initial
-	 * set mode. Use restore_backlight flag to avoid setting backlight level
-	 * for every subsequent mode set.
+	 * So we set the backlight level with dm->brightness value after set mode
 	 */
-	if (dm->restore_backlight) {
+	if (set_backlight_level) {
 		for (i = 0; i < dm->num_of_edps; i++) {
 			if (dm->backlight_dev[i])
 				amdgpu_dm_backlight_set_level(dm, i, dm->brightness[i]);
 		}
-		dm->restore_backlight = false;
 	}
 }
 

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

@@ -630,13 +630,6 @@ struct amdgpu_display_manager {
 	 */
 	u32 actual_brightness[AMDGPU_DM_MAX_NUM_EDP];
 
-	/**
-	 * @restore_backlight:
-	 *
-	 * Flag to indicate whether to restore backlight after modeset.
-	 */
-	bool restore_backlight;
-
 	/**
 	 * @aux_hpd_discon_quirk:
 	 *