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drm/amd/display: Force PWM backlight on Lenovo Legion 5 15ARH05

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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 <ale@alerinaldi.it>
Tested-by: Alessandro Rinaldi <ale@alerinaldi.it>
Reviewed-by: George Zhang <george.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 81b39f43e7e53589491e2eef6bad5389626b4b9c)
Cc: stable@vger.kernel.org
This commit is contained in:
Alessandro Rinaldi
2026-06-26 16:36:00 +02:00
committed by Alex Deucher
parent b240f792ae
commit bad177fa75
3 changed files with 15 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
View File

@@ -4069,6 +4069,8 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
caps->ext_caps = &aconnector->dc_link->dpcd_sink_ext_caps;
caps->aux_support = false;
panel_backlight_quirk = drm_get_panel_backlight_quirk(aconnector->drm_edid);
if (caps->ext_caps->bits.oled == 1
/*
* ||
@@ -4081,6 +4083,9 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
caps->aux_support = false;
else if (amdgpu_backlight == 1)
caps->aux_support = true;
else if (!IS_ERR_OR_NULL(panel_backlight_quirk) &&
panel_backlight_quirk->force_pwm)
caps->aux_support = false;
if (caps->aux_support)
aconnector->dc_link->backlight_control_type = BACKLIGHT_CONTROL_AMD_AUX;
@@ -4096,8 +4101,6 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
else
caps->aux_min_input_signal = 1;
panel_backlight_quirk =
drm_get_panel_backlight_quirk(aconnector->drm_edid);
if (!IS_ERR_OR_NULL(panel_backlight_quirk)) {
if (panel_backlight_quirk->min_brightness) {
caps->min_input_signal =

9
drivers/gpu/drm/drm_panel_backlight_quirks.c
View File

@@ -20,6 +20,15 @@ struct drm_get_panel_backlight_quirk {
};
static const struct drm_get_panel_backlight_quirk drm_panel_min_backlight_quirks[] = {
/* Lenovo Legion 5 15ARH05, AUX backlight non-functional, force PWM */
{
.dmi_match.field = DMI_SYS_VENDOR,
.dmi_match.value = "LENOVO",
.dmi_match_other.field = DMI_PRODUCT_VERSION,
.dmi_match_other.value = "Lenovo Legion 5 15ARH05",
.ident.panel_id = drm_edid_encode_panel_id('B', 'O', 'E', 0x08df),
.quirk = { .force_pwm = true, },
},
/* 13 inch matte panel */
{
.dmi_match.field = DMI_BOARD_VENDOR,

1
include/drm/drm_utils.h
View File

@@ -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 *