VRR over MST:
- Remove the hard MST block in intel_vrr_is_capable(); check the
  downstream port's MSA timing par ignore capability via REMOTE_DPCD_READ
  and cache it in connector->dp.mst_msa_timing_par_ignore to avoid hot
  path sideband round-trips.
- Read mst_msa_timing_par_ignore unconditionally from the sink's virtual
  DPCD before the DSC decompression check, so VRR works on MST sinks
  without DSC support.
- Attach vrr_capable property by reusing the root SST connector's existing
  property object (MST connectors are created post device-registration so
  new properties cannot be created).
- Update vrr_capable after EDID read; gate AS-SDP and 
DP_MSA_TIMING_PAR_IGNORE_EN
  writes on pipe_config->vrr.enable (actual state) not intel_vrr_is_capable()
  (capability); allow AS-SDP through MST hubs by excluding only non-MST
  branch devices (PCONs) from the branch device check.

HDR metadata over MST:
- Add VSC SDP, HDR metadata infoframe SDP and AS-SDP computation to
  mst_stream_compute_config() and enable their transmission in
  mst_stream_enable() and intel_ddi_update_pipe().
- Lift the hard 8bpc pipe_bpp cap and use the bpp capability from sink EDID
  for MST streams to allow 10bpc, relying on
  intel_dp_mst_atomic_check_link()'s BW retry loop to fall back if the
  link cannot fit it.

Signed-off-by: Xiao Lu <[email protected]>
---
 drivers/gpu/drm/display/drm_dp_mst_topology.c |  2 +
 drivers/gpu/drm/i915/display/intel_ddi.c      |  3 +
 .../drm/i915/display/intel_display_types.h    |  1 +
 drivers/gpu/drm/i915/display/intel_dp.c       | 36 ++++----
 drivers/gpu/drm/i915/display/intel_dp.h       |  8 ++
 drivers/gpu/drm/i915/display/intel_dp_mst.c   | 83 +++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_vrr.c      | 23 ++++-
 7 files changed, 139 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c 
b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 7ce9e212770a..174fa62cb0dc 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -2164,6 +2164,7 @@ ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
        return drm_dp_send_dpcd_read(port->mgr, port,
                                     offset, size, buffer);
 }
+EXPORT_SYMBOL(drm_dp_mst_dpcd_read);
 
 /**
  * drm_dp_mst_dpcd_write() - write a series of bytes to the DPCD via sideband
@@ -2187,6 +2188,7 @@ ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,
        return drm_dp_send_dpcd_write(port->mgr, port,
                                      offset, size, buffer);
 }
+EXPORT_SYMBOL(drm_dp_mst_dpcd_write);
 
 static int drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, guid_t *guid)
 {
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c 
b/drivers/gpu/drm/i915/display/intel_ddi.c
index b8985e1e0a81..f345d9a2154d 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -3651,6 +3651,9 @@ void intel_ddi_update_pipe(struct intel_atomic_state 
*state,
                intel_ddi_update_pipe_dp(state, encoder, crtc_state,
                                         conn_state);
 
+       if (intel_encoder_is_mst(encoder))
+               intel_dp_set_infoframes(encoder, true, crtc_state, conn_state);
+
        if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI))
                intel_ddi_update_pipe_hdmi(encoder, crtc_state,
                                           conn_state);
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h 
b/drivers/gpu/drm/i915/display/intel_display_types.h
index b7cc361fd955..d09cf18f5376 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -564,6 +564,7 @@ struct intel_connector {
                u8 dsc_hblank_expansion_quirk:1;
                u8 dsc_throughput_quirk:1;
                u8 dsc_decompression_enabled:1;
+               u8 mst_msa_timing_par_ignore:1; /* cached from MST virtual DPCD 
0x007 */
 
                struct {
                        struct {
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c 
b/drivers/gpu/drm/i915/display/intel_dp.c
index 113d767e62e9..4b196d26d27f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2682,15 +2682,18 @@ intel_dp_compute_config_limits(struct intel_dp 
*intel_dp,
 
        limits->pipe.min_bpp = intel_dp_min_bpp(crtc_state->output_format);
        if (is_mst) {
+               struct intel_connector *mst_connector =
+                       to_intel_connector(conn_state->connector);
+               int sink_bpc = mst_connector->base.display_info.bpc ?: 8;
+
                /*
-                * FIXME: If all the streams can't fit into the link with their
-                * current pipe_bpp we should reduce pipe_bpp across the board
-                * until things start to fit. Until then we limit to <= 8bpc
-                * since that's what was hardcoded for all MST streams
-                * previously. This hack should be removed once we have the
-                * proper retry logic in place.
+                * For MST streams, use the sink's EDID-reported color depth
+                * as the max bpp, rather than the pipe_bpp from a previous
+                * modeset (which may be stale) or a hardcoded 8bpc cap.
+                * The BW retry loop in intel_dp_mst_atomic_check_link() will
+                * reduce bpp if the aggregate link bandwidth is insufficient.
                 */
-               limits->pipe.max_bpp = min(crtc_state->max_pipe_bpp, 24);
+               limits->pipe.max_bpp = sink_bpc * 3;
        } else {
                limits->pipe.max_bpp = intel_dp_max_bpp(intel_dp, crtc_state,
                                                        
respect_downstream_limits);
@@ -3107,9 +3110,12 @@ static bool intel_dp_needs_as_sdp(struct intel_dp 
*intel_dp,
                return false;
 
        /*
-        * #TODO: Add AS SDP v1 support for PCONs (DP branch devices).
+        * AS-SDP is not yet supported for PCONs (DP-to-HDMI converters).
+        * MST hubs are also branch devices but do support AS-SDP forwarding
+        * to downstream sinks; allow it for MST streams.
         */
-       if (drm_dp_is_branch(intel_dp->dpcd))
+       if (drm_dp_is_branch(intel_dp->dpcd) &&
+           !intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST))
                return false;
 
        if (intel_psr_needs_alpm_aux_less(intel_dp, crtc_state) &&
@@ -3119,8 +3125,8 @@ static bool intel_dp_needs_as_sdp(struct intel_dp 
*intel_dp,
        return intel_vrr_possible(crtc_state);
 }
 
-static void intel_dp_compute_as_sdp(struct intel_dp *intel_dp,
-                                   struct intel_crtc_state *crtc_state)
+void intel_dp_compute_as_sdp(struct intel_dp *intel_dp,
+                            struct intel_crtc_state *crtc_state)
 {
        struct drm_dp_as_sdp *as_sdp = &crtc_state->infoframes.as_sdp;
        const struct drm_display_mode *adjusted_mode =
@@ -3169,9 +3175,9 @@ static void intel_dp_compute_as_sdp(struct intel_dp 
*intel_dp,
                as_sdp->coasting_vtotal = crtc_state->vrr.vmax;
 }
 
-static void intel_dp_compute_vsc_sdp(struct intel_dp *intel_dp,
-                                    struct intel_crtc_state *crtc_state,
-                                    const struct drm_connector_state 
*conn_state)
+void intel_dp_compute_vsc_sdp(struct intel_dp *intel_dp,
+                             struct intel_crtc_state *crtc_state,
+                             const struct drm_connector_state *conn_state)
 {
        struct drm_dp_vsc_sdp *vsc;
 
@@ -3228,7 +3234,7 @@ intel_dp_in_hdr_mode(const struct drm_connector_state 
*conn_state)
        return hdr_metadata->hdmi_metadata_type1.eotf == HDMI_EOTF_SMPTE_ST2084;
 }
 
-static void
+void
 intel_dp_compute_hdr_metadata_infoframe_sdp(struct intel_dp *intel_dp,
                                            struct intel_crtc_state *crtc_state,
                                            const struct drm_connector_state 
*conn_state)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h 
b/drivers/gpu/drm/i915/display/intel_dp.h
index 04fae203bb69..bb68bc3876d6 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -77,6 +77,8 @@ int intel_dp_compute_config(struct intel_atomic_state *state,
                            struct intel_encoder *encoder,
                            struct intel_crtc_state *pipe_config,
                            struct drm_connector_state *conn_state);
+void intel_dp_compute_as_sdp(struct intel_dp *intel_dp,
+                            struct intel_crtc_state *crtc_state);
 bool intel_dp_needs_8b10b_fec(const struct intel_crtc_state *crtc_state,
                              bool dsc_enabled_on_crtc);
 void intel_dp_dsc_reset_config(struct intel_crtc_state *crtc_state);
@@ -130,6 +132,12 @@ bool intel_dp_joiner_needs_dsc(struct intel_display 
*display,
 bool intel_dp_has_joiner(struct intel_dp *intel_dp);
 bool intel_dp_needs_vsc_colorimetry(const struct intel_crtc_state *crtc_state,
                                    const struct drm_connector_state 
*conn_state);
+void intel_dp_compute_vsc_sdp(struct intel_dp *intel_dp,
+                             struct intel_crtc_state *crtc_state,
+                             const struct drm_connector_state *conn_state);
+void intel_dp_compute_hdr_metadata_infoframe_sdp(struct intel_dp *intel_dp,
+                                                 struct intel_crtc_state 
*crtc_state,
+                                                 const struct 
drm_connector_state *conn_state);
 void intel_dp_set_infoframes(struct intel_encoder *encoder, bool enable,
                             const struct intel_crtc_state *crtc_state,
                             const struct drm_connector_state *conn_state);
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c 
b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 3be1643f8d03..e66f9508cb72 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -793,6 +793,9 @@ static int mst_stream_compute_config(struct 
intel_atomic_state *state,
                        
bxt_dpio_phy_calc_lane_lat_optim_mask(pipe_config->lane_count);
 
        intel_vrr_compute_config(pipe_config, conn_state);
+       intel_dp_compute_as_sdp(intel_dp, pipe_config);
+       intel_dp_compute_vsc_sdp(intel_dp, pipe_config, conn_state);
+       intel_dp_compute_hdr_metadata_infoframe_sdp(intel_dp, pipe_config, 
conn_state);
 
        intel_dp_audio_compute_config(encoder, pipe_config, conn_state);
 
@@ -1157,6 +1160,24 @@ static void mst_stream_post_disable(struct 
intel_atomic_state *state,
         * Power down mst path before disabling the port, otherwise we end
         * up getting interrupts from the sink upon detecting link loss.
         */
+       if (old_crtc_state->vrr.enable) {
+               u8 val;
+               ssize_t ret;
+
+               ret = drm_dp_mst_dpcd_read(&connector->mst.port->aux,
+                                          DP_DOWNSPREAD_CTRL, &val, 1);
+               if (ret < 0) {
+                       drm_dbg_kms(display->drm,
+                                   "[CONNECTOR:%d:%s] Failed to read 
DP_DOWNSPREAD_CTRL: %zd\n",
+                                   connector->base.base.id,
+                                   connector->base.name, ret);
+               } else {
+                       val &= ~DP_MSA_TIMING_PAR_IGNORE_EN;
+                       drm_dp_mst_dpcd_write(&connector->mst.port->aux,
+                                             DP_DOWNSPREAD_CTRL, &val, 1);
+               }
+       }
+
        drm_dp_send_power_updown_phy(&intel_dp->mst.mgr, connector->mst.port,
                                     false);
 
@@ -1274,6 +1295,24 @@ static void mst_stream_pre_enable(struct 
intel_atomic_state *state,
 
        drm_dp_send_power_updown_phy(&intel_dp->mst.mgr, connector->mst.port, 
true);
 
+       if (pipe_config->vrr.enable) {
+               u8 val;
+               ssize_t ret;
+
+               ret = drm_dp_mst_dpcd_read(&connector->mst.port->aux,
+                                          DP_DOWNSPREAD_CTRL, &val, 1);
+               if (ret < 0) {
+                       drm_dbg_kms(display->drm,
+                                   "[CONNECTOR:%d:%s] Failed to read 
DP_DOWNSPREAD_CTRL: %zd\n",
+                                   connector->base.base.id,
+                                   connector->base.name, ret);
+               } else {
+                       val |= DP_MSA_TIMING_PAR_IGNORE_EN;
+                       drm_dp_mst_dpcd_write(&connector->mst.port->aux,
+                                             DP_DOWNSPREAD_CTRL, &val, 1);
+               }
+       }
+
        intel_dp_sink_enable_decompression(state, connector, pipe_config);
 
        if (first_mst_stream) {
@@ -1397,6 +1436,8 @@ static void mst_stream_enable(struct intel_atomic_state 
*state,
 
        intel_enable_transcoder(pipe_config);
 
+       intel_dp_set_infoframes(encoder, true, pipe_config, conn_state);
+
        for_each_pipe_crtc_modeset_enable(display, pipe_crtc, pipe_config) {
                const struct intel_crtc_state *pipe_crtc_state =
                        intel_atomic_get_new_crtc_state(state, pipe_crtc);
@@ -1451,6 +1492,15 @@ static int mst_connector_get_ddc_modes(struct 
drm_connector *_connector)
 
        ret = intel_connector_update_modes(&connector->base, drm_edid);
 
+       if (HAS_VRR(display)) {
+               bool vrr_capable = intel_vrr_is_capable(connector);
+
+               drm_dbg_kms(display->drm, "[CONNECTOR:%d:%s] VRR capable: %s\n",
+                           connector->base.base.id, connector->base.name,
+                           str_yes_no(vrr_capable));
+               drm_connector_set_vrr_capable_property(&connector->base, 
vrr_capable);
+       }
+
        drm_edid_free(drm_edid);
 
        if (intel_dp_tunnel_uhbr_lanes_wa_setup(intel_dp)) {
@@ -1735,6 +1785,10 @@ static int mst_topology_add_connector_properties(struct 
intel_dp *intel_dp,
 
        intel_attach_force_audio_property(&connector->base);
        intel_attach_broadcast_rgb_property(&connector->base);
+       intel_attach_dp_colorspace_property(&connector->base);
+
+       if (intel_dp_has_gamut_metadata_dip(&dp_to_dig_port(intel_dp)->base))
+               
drm_connector_attach_hdr_output_metadata_property(&connector->base);
 
        /*
         * Reuse the prop from the SST connector because we're
@@ -1745,6 +1799,23 @@ static int mst_topology_add_connector_properties(struct 
intel_dp *intel_dp,
        if (connector->base.max_bpc_property)
                drm_connector_attach_max_bpc_property(&connector->base, 6, 12);
 
+       /*
+        * Reuse the vrr_capable prop from the eDP connector (which is always
+        * initialized during driver load before device registration), because
+        * we're not allowed to create new props after device registration.
+        */
+       /*
+        * Reuse the vrr_capable property from the root intel_dp SST connector
+        * which was created during driver load (before device registration).
+        * MST connectors are created after device registration, so we cannot
+        * create new properties here - we must attach the existing one.
+        */
+       if (HAS_VRR(display) && intel_dp->attached_connector &&
+           intel_dp->attached_connector->base.vrr_capable_property)
+               drm_object_attach_property(&connector->base.base,
+                                          
intel_dp->attached_connector->base.vrr_capable_property,
+                                          0);
+
        return drm_connector_set_path_property(&connector->base, pathprop);
 }
 
@@ -1755,6 +1826,18 @@ intel_dp_mst_read_decompression_port_dsc_caps(struct 
intel_dp *intel_dp,
        u8 dpcd_caps[DP_RECEIVER_CAP_SIZE];
        struct drm_dp_desc desc;
 
+       /*
+        * Read MSA timing par ignore capability from the sink's virtual DPCD.
+        * This is independent of DSC support so read it before the DSC check.
+        */
+       {
+               u8 mst_dpcd[DP_RECEIVER_CAP_SIZE];
+
+               if (drm_dp_read_dpcd_caps(&connector->mst.port->aux, mst_dpcd) 
== 0)
+                       connector->dp.mst_msa_timing_par_ignore =
+                               
drm_dp_sink_can_do_video_without_timing_msa(mst_dpcd);
+       }
+
        if (!connector->dp.dsc_decompression_aux)
                return;
 
diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c 
b/drivers/gpu/drm/i915/display/intel_vrr.c
index 51e4f3309b8b..13cd5701bf2c 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -55,8 +55,27 @@ bool intel_vrr_is_capable(struct intel_connector *connector)
                        return false;
                fallthrough;
        case DRM_MODE_CONNECTOR_DisplayPort:
-               if (connector->mst.dp)
-                       return false;
+               if (connector->mst.dp) {
+                       u8 dpcd[DP_RECEIVER_CAP_SIZE];
+
+                       /*
+                        * Use cached MSA timing ignore capability from the DFP
+                        * sink's virtual DPCD, set during connector init.
+                        */
+                       if (!connector->dp.mst_msa_timing_par_ignore)
+                               return false;
+
+                       /*
+                        * Also verify live via LCT=2 REMOTE_DPCD_READ to the
+                        * DFP sink's actual DPCD 0x007.
+                        */
+                       if (drm_dp_read_dpcd_caps(&connector->mst.port->aux, 
dpcd) < 0)
+                               return false;
+                       if (!drm_dp_sink_can_do_video_without_timing_msa(dpcd))
+                               return false;
+
+                       break;
+               }
                intel_dp = intel_attached_dp(connector);
                /*
                 * Among non-MST DP branch devices, only an HDMI 2.1 sink 
connected
-- 
2.43.0

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