On Mon, Nov 15, 2021 at 2:35 AM Samuel Čavoj samuel@cavoj.net wrote:
Hello,
the backlight control no longer works on my ASUS UM325 (Ryzen 5700U) OLED laptop. I have bisected the breakage to commit 7fd13baeb7a3a48.
commit 7fd13baeb7a3a48cae12c36c52f06bf4e9e7d728 (HEAD, refs/bisect/bad) Author: Alex Deucher <alexander.deucher@amd.com> Date: Thu Jul 8 16:31:10 2021 -0400 drm/amdgpu/display: add support for multiple backlights On platforms that support multiple backlights, register each one separately. This lets us manage them independently rather than registering a single backlight and applying the same settings to both. v2: fix typo: Reported-by: kernel test robot <lkp@intel.com> Reviewed-by: Roman Li <Roman.Li@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>I have encountered another user with the same issue on reddit[0].
The node in /sys/class/backlight exists, writing to it just does nothing. I would be glad to help debugging the issue. Thank you very much.
That patch adds support for systems with multiple backlights. Do you have multiple backlight devices now? If so, does the other one work?
Can you also try this patch?
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c index 4811b0faafd9..67163c9d49e6 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c @@ -854,8 +854,8 @@ int amdgpu_acpi_init(struct amdgpu_device *adev) if (amdgpu_device_has_dc_support(adev)) { #if defined(CONFIG_DRM_AMD_DC) struct amdgpu_display_manager *dm = &adev->dm; - if (dm->backlight_dev[0]) - atif->bd = dm->backlight_dev[0]; + if (dm->backlight_dev[1]) + atif->bd = dm->backlight_dev[1]; #endif } else { struct drm_encoder *tmp;
Alex
Regards, Samuel Čavoj