On 2026-08-06 16:54, Fangzhi Zuo wrote: > why: > HDMI 2.1 Auto Low-Latency Mode (ALLM) lets a Source request the Sink's > low-latency mode through the HF-VSIF. amdgpu never set ALLM_Mode in the > HF-VSIF, so ALLM was never signalled to the sink. > > how: > - In create_stream_for_sink(), build the HF-VSIF with ALLM_Mode set when > the sink advertises ALLM (connector->display_info.hdmi.allm, parsed by > DRM core from the HF-VSDB) and the content type is Game (content-type = > Game is how userspace requests low-latency mode, HDMI GCTS HF1-56). > - In update_freesync_state_on_stream(), also set ALLM_Mode when > Gaming-VRR is active (VRR_EN=1, HDMI GCTS HF1-58 step 8.3.1), and push > the updated HF-VSIF (vsp_infopacket) as a stream update. > > Signed-off-by: Fangzhi Zuo <[email protected]>
Reviewed-by: Harry Wentland <[email protected]> Harry > --- > .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 ++- > .../display/amdgpu_dm/amdgpu_dm_connector.c | 18 +++++++++-- > .../display/amdgpu_dm/amdgpu_dm_freesync.c | 31 +++++++++++++++++++ > 3 files changed, 51 insertions(+), 3 deletions(-) > > 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 567bf04979ee..ff0db0cb9880 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -4029,9 +4029,12 @@ static void amdgpu_dm_commit_planes(struct > drm_atomic_commit *state, > } > > if (acrtc_state->stream) { > - if (acrtc_state->freesync_vrr_info_changed) > + if (acrtc_state->freesync_vrr_info_changed) { > bundle->stream_update.vrr_infopacket = > &acrtc_state->stream->vrr_infopacket; > + bundle->stream_update.vsp_infopacket = > + &acrtc_state->stream->vsp_infopacket; > + } > } > } > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c > index df39bc70ec6c..6cfd7526ab56 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c > @@ -1572,8 +1572,22 @@ create_stream_for_sink(struct drm_connector *connector, > update_stream_signal(stream, sink); > > if (stream->signal == SIGNAL_TYPE_HDMI_TYPE_A || > - stream->signal == SIGNAL_TYPE_HDMI_FRL) > - mod_build_hf_vsif_infopacket(stream, &stream->vsp_infopacket, > false, false); > + stream->signal == SIGNAL_TYPE_HDMI_FRL) { > + /* > + * Enable HDMI ALLM (Auto Low-Latency Mode) when the sink > + * advertises ALLM in the SCDS and the content type is Game. > + * Setting content-type = Game is how userspace requests the > + * Sink's low-latency mode (HDMI GCTS HF1-56). > + */ > + bool allm = connector->display_info.hdmi.allm && > + stream->content_type == DISPLAY_CONTENT_TYPE_GAME; > + > + drm_dbg_driver(dev, > + "ALLM: set mode: sink_allm=%d content_type=%d -> > ALLM_Mode=%d\n", > + connector->display_info.hdmi.allm, > stream->content_type, allm); > + > + mod_build_hf_vsif_infopacket(stream, &stream->vsp_infopacket, > allm, allm); > + } > > if (stream->signal == SIGNAL_TYPE_DISPLAY_PORT || > stream->signal == SIGNAL_TYPE_DISPLAY_PORT_MST || > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c > index cb49184813de..c4bc6e717df9 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c > @@ -252,6 +252,37 @@ void amdgpu_dm_update_freesync_state_on_stream( > new_stream->vrr_infopacket = vrr_infopacket; > new_stream->allow_freesync = > mod_freesync_get_freesync_enabled(&vrr_params); > > + /* > + * HDMI ALLM: transmit the HF-VSIF with ALLM_Mode=1 when the sink > + * advertises ALLM in the SCDS and either the content type is Game > + * (HF1-56) or Gaming-VRR is active (VRR_EN=1, HF1-58 step 8.3.1). > + * HDMI 2.1 7.6.6. > + */ > + if (new_stream->signal == SIGNAL_TYPE_HDMI_TYPE_A || > + new_stream->signal == SIGNAL_TYPE_HDMI_FRL) { > + struct dc_info_packet vsp_infopacket = {0}; > + bool sink_allm = aconn && aconn->base.display_info.hdmi.allm; > + bool allm = sink_allm && > + (new_stream->content_type == DISPLAY_CONTENT_TYPE_GAME > || > + vrr_params.state == VRR_STATE_ACTIVE_VARIABLE || > + vrr_params.state == VRR_STATE_ACTIVE_FIXED); > + bool allm_changed; > + > + mod_build_hf_vsif_infopacket(new_stream, &vsp_infopacket, allm, > allm); > + > + allm_changed = memcmp(&new_stream->vsp_infopacket, > &vsp_infopacket, > + sizeof(vsp_infopacket)) != 0; > + new_crtc_state->freesync_vrr_info_changed |= allm_changed; > + new_stream->vsp_infopacket = vsp_infopacket; > + > + if (allm_changed) > + drm_dbg_driver(adev_to_drm(adev), > + "ALLM: flip on crtc=%u: sink_allm=%d > content_type=%d vrr_state=%d -> ALLM_Mode=%d\n", > + new_crtc_state->base.crtc->base.id, > + sink_allm, > + new_stream->content_type, vrr_params.state, > allm); > + } > + > if (new_crtc_state->freesync_vrr_info_changed) > drm_dbg_kms(adev_to_drm(adev), "VRR packet update: crtc=%u > enabled=%d state=%d", > new_crtc_state->base.crtc->base.id,
