On 2019-10-23 10:19 a.m., Lukáš Krejčí wrote:
On Mon, 2019-10-21 at 15:44 -0400, sunpeng.li@amd.com wrote:
From: Leo Li sunpeng.li@amd.com
[Why]
Some LED panel drivers might not like fractional PWM. In such cases, backlight flickering may be observed.
[How]
Add a DC feature mask to disable fractional PWM, and associate it with the preexisting dc_config flag.
The flag is only plumbed through the dmcu firmware, so plumb it through the driver path as well.
To disable, add the following to the linux cmdline: amdgpu.dcfeaturemask=0x4
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204957 Signed-off-by: Leo Li sunpeng.li@amd.com
v2: Add bugzilla link
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +++ drivers/gpu/drm/amd/display/dc/dce/dce_abm.c | 4 ++++ drivers/gpu/drm/amd/include/amd_shared.h | 1 + 3 files changed, 8 insertions(+)
Tested on Ubuntu 19.04, vanilla v5.3.7 kernel with the patch applied and amdgpu.dcfeaturemask=0x4 added to the kernel command line, no issues after 8 reboots. (The issue could be reproduced without amdgpu.dcfeaturemask=0x4 on first boot.)
Tested-by: Lukáš Krejčí lskrejci@gmail.com
Applied, thanks! Leo