linux-kernel - [PATCH v2] Revert "drm/amd/display: Only restore backlight after amdgpu_dm_init or dm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251009121900.12777-1-matthew.schwartz@linux.dev>
Date: Thu,  9 Oct 2025 14:19:00 +0200
From: Matthew Schwartz <matthew.schwartz@...ux.dev>
To: harry.wentland@....com,
	christian.koenig@....com,
	sunpeng.li@....com,
	airlied@...il.com,
	simona@...ll.ch,
	alexander.deucher@....com
Cc: linux-kernel@...r.kernel.org,
	mario.limonciello@....com,
	amd-gfx@...ts.freedesktop.org,
	regressions@...ts.linux.dev,
	Matthew Schwartz <matthew.schwartz@...ux.dev>,
	stable@...r.kernel.org
Subject: [PATCH v2] Revert "drm/amd/display: Only restore backlight after amdgpu_dm_init or dm_resume"

This fix regressed the original issue that commit d83c747a1225
("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: a490c8d77d50 ("drm/amd/display: Only restore backlight after amdgpu_dm_init or dm_resume")
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4620
Cc: stable@...r.kernel.org
Signed-off-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
---
v1 -> v2:
- Fix missing stable tag
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 12 ++++--------
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  7 -------
 2 files changed, 4 insertions(+), 15 deletions(-)

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 8e1622bf7a42..21281e684b84 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2081,8 +2081,6 @@ 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");
@@ -3438,7 +3436,6 @@ 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);
 
@@ -9965,6 +9962,7 @@ 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) {
@@ -10084,6 +10082,7 @@ 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",
@@ -10140,16 +10139,13 @@ 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;
 	}
 }
 
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index 009f206226f0..db75e991ac7b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/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:
 	 *
-- 
2.51.0