kernel/drivers/gpu/drm/amd/display/dc/hubbub, branch linux-rolling-stable

drm/amd/display: dynamically clock gate before and after prefetch

2025-11-12T02:54:16Z

[Why] An invalidation request arriving during prefetch can potentially hang the system if dynamic clock gating is enabled and memory power requests are disabled. [How] • Disable clock gating and enable memory power requests for the duration of the prefetch. • Turn on clock gating and disable memory power requests again after prefetch is complete. Limit the scope for DCN35 and DCN42 only. Reviewed-by: Nicholas Kazlauskas Signed-off-by: Leo Chen Signed-off-by: Fangzhi Zuo Tested-by: Dan Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Add more DC HW state info to underflow logging

2025-10-28T13:57:44Z

[Why] Debugging underflow issues frequently requires knowing the HW state at the time of underflow. To enable capturing this HW state information, interface functions are needed for the various DC HW blocks. [How] This change adds the interface functions to read HW state for the following DC HW blocks: - HUBBUB - HUBP - DPP - MPC - OPP - DSC - OPTC - DCCG Reviewed-by: George Shen Signed-off-by: Karen Chen Signed-off-by: Wayne Lin Tested-by: Dan Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Set wm_pending when disable stutter w/a used

2025-09-23T14:31:58Z

[WHY&HOW] When stutter is disabled prior to watermark programming due to a w/a, wm_pending should be returned as true. Reviewed-by: Nicholas Kazlauskas Reviewed-by: Aurabindo Pillai Signed-off-by: Dillon Varone Signed-off-by: Ivan Lipski Tested-by: Dan Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Disable stutter when programming watermarks on dcn32

2025-09-23T14:26:10Z

[WHY&HOW] Reprogramming watermarks with stutter allowed can cause instability on some ASICs. Disable it prior to raising watermarks (prepare bandwidth), then re-enable after lowering (optimize bandwidth). Reviewed-by: Alvin Lee Signed-off-by: Dillon Varone Signed-off-by: Ivan Lipski Tested-by: Dan Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Adding interface to log hw state when underflow happens

2025-08-04T18:40:32Z

[why] Will help us better debug underflow issues. Reviewed-by: Nicholas Kazlauskas Signed-off-by: Muhammad Ahmed Signed-off-by: Roman Li Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Add skip rIOMMU dc config option

2025-05-05T16:58:17Z

[Why] Need option to skip rIOMMU calls for dcn21. [How] Added rIOMMU dc config option and check for whether to skip rIOMMU calls. Reviewed-by: Nicholas Kazlauskas Signed-off-by: Kevin Gao Signed-off-by: Ray Wu Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Remove unused hubbub1_toggle_watermark_change_req

2025-02-13T02:03:03Z

hubbub1_toggle_watermark_change_req() last use was removed in 2017 by commit b8fce2c9d773 ("drm/amd/display: Optimize programming front end") Remove it. Signed-off-by: Dr. David Alan Gilbert Signed-off-by: Alex Deucher

drm/amd/display: Allow reuse of of DCN4x code

2025-02-13T02:03:01Z

Remove the static qualifier to make it available for code sharing with other components. Reviewed-by: Charlene Liu Signed-off-by: Dmytro Signed-off-by: Charlene Liu Signed-off-by: Alex Hung Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Fix seamless boot sequence

2025-02-03T17:13:38Z

[WHY] When the system powers up eDP with external monitors in seamless boot sequence, stutter get enabled before TTU and HUBP registers being programmed, which resulting in underflow. [HOW] Enable TTU in hubp_init. Change the sequence that do not perpare_bandwidth and optimize_bandwidth while having seamless boot streams. Cc: Mario Limonciello Cc: Alex Deucher Cc: stable@vger.kernel.org Reviewed-by: Nicholas Kazlauskas Signed-off-by: Lo-an Chen Signed-off-by: Paul Hsieh Signed-off-by: Alex Hung Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Enable Request rate limiter during C-State on dcn401

2024-11-20T14:39:42Z

[WHY] When C-State entry is requested, the rate limiter will be disabled which can result in high contention in the DCHUB return path. [HOW] Enable the rate limiter during C-state requests to prevent contention. Cc: stable@vger.kernel.org # 6.11+ Reviewed-by: Alvin Lee Signed-off-by: Dillon Varone Signed-off-by: Hamza Mahfooz Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher