On Tue, Oct 27, 2026 at 5:41 AM Richard Lane <[email protected]> wrote: > > When driving both 2560x2880 tiles of an Apple 5K iMac panel, Display > Core's program_timing_sync() already aligns both CRTCs in hardware > during dc_commit_streams() because the two streams share identical > timings. > > However, on DCE < 12 (iMac15,1 through Polaris-based iMac19,1), Display > Core leaves pp_display_cfg.all_displays_in_sync unset. Because PowerPlay > is not informed that the two streams have synchronized vertical blanking > intervals, SMU7 prevents MCLK switching at idle or causes modeset > underflows. > > Report all_displays_in_sync = true to PowerPlay after committing both > tiled streams so SMU7 knows the tiles blank simultaneously and can > safely downclock MCLK at idle. > > Signed-off-by: Richard Lane <[email protected]> > --- > drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > index 548f975c7324..384a81371f80 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -4788,6 +4788,19 @@ static void amdgpu_dm_commit_streams(struct > drm_atomic_commit *state, > mutex_lock(&dm->dc_lock); > dc_exit_ips_for_hw_access(dm->dc); > WARN_ON(!dc_commit_streams(dm->dc, ¶ms)); > + /* > + * DCE < 12 leaves all_displays_in_sync unset; report synchronized > + * Apple 5K tiles to PowerPlay after commit so SMU7 can downclock MCLK > + * at idle without modeset underflows. > + */ > + if (params.stream_count == 2 && > + params.streams[0]->link->tiled_peer == params.streams[1]->link) {
This should be made generic for any combination of displays with identical timings. Alex > + struct dm_pp_display_configuration *pp_cfg = > + &dm->dc->current_state->pp_display_cfg; > + > + pp_cfg->all_displays_in_sync = true; > + dm_pp_apply_display_requirements(dm->dc->ctx, pp_cfg); > + } > > bool frl_stream_found = false; > > -- > 2.55.0
