From bad177fa75e607e396cd57daaaed881450d7a471 Mon Sep 17 00:00:00 2001 From: Alessandro Rinaldi Date: Fri, 26 Jun 2026 16:36:00 +0200 Subject: drm/amd/display: Force PWM backlight on Lenovo Legion 5 15ARH05 The Lenovo Legion 5 15ARH05 (Renoir) ships a BOE 0x08DF eDP panel that advertises AUX/DPCD backlight control, so amdgpu's automatic detection (amdgpu_backlight == -1) selects AUX. On this panel the AUX backlight path has no effect: brightness writes are accepted but the panel level never changes, the display is stuck at a fixed brightness and max_brightness is reported as a bogus 511000. As a result neither the desktop brightness slider nor the brightness hotkeys do anything. Forcing PWM backlight (amdgpu.backlight=0) restores working control: max_brightness becomes 65535 and the level tracks writes. This has long been applied by users as a manual kernel-parameter workaround. Extend the generic panel backlight quirk with a force_pwm flag, add an entry for the Legion 5 15ARH05 / BOE 0x08DF panel, and have amdgpu disable AUX backlight (use PWM) when the quirk matches and the user lets the driver auto-select the backlight type. Signed-off-by: Alessandro Rinaldi Tested-by: Alessandro Rinaldi Reviewed-by: George Zhang Signed-off-by: Alex Deucher (cherry picked from commit 81b39f43e7e53589491e2eef6bad5389626b4b9c) Cc: stable@vger.kernel.org --- include/drm/drm_utils.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/drm/drm_utils.h b/include/drm/drm_utils.h index 6a46f755daba..7e077484c5bb 100644 --- a/include/drm/drm_utils.h +++ b/include/drm/drm_utils.h @@ -19,6 +19,7 @@ int drm_get_panel_orientation_quirk(int width, int height); struct drm_panel_backlight_quirk { u16 min_brightness; u32 brightness_mask; + bool force_pwm; }; const struct drm_panel_backlight_quirk * -- cgit v1.2.3