128b/132b supports using 64 slots starting from 0, while 8b/10b reserves
slot 0 for metadata.

Commit d6c6a76f80a1 ("drm: Update MST First Link Slot Information Based
on Encoding Format") added support for updating the topology state
accordingly, and commit 41724ea273cd ("drm/amd/display: Add DP 2.0 MST
DM Support") started using it in the amd driver.

This feels more than a little cumbersome, especially updating the
information in atomic check. For i915, add the update to MST connector
.atomic_check hook rather than iterating over all MST managers and
connectors in global mode config .atomic_check. Fingers crossed.

Cc: Bhawanpreet Lakha <[email protected]>
Cc: Lyude Paul <[email protected]>
Cc: Uma Shankar <[email protected]>
Cc: Ville Syrjälä <[email protected]>
Signed-off-by: Jani Nikula <[email protected]>
---
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c 
b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index b8bc7d397c81..d13c7952a8d6 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -302,6 +302,8 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
        if (!old_conn_state->crtc)
                return 0;
 
+       mgr = 
&enc_to_mst(to_intel_encoder(old_conn_state->best_encoder))->primary->dp.mst_mgr;
+
        /* We only want to free VCPI if this state disables the CRTC on this
         * connector
         */
@@ -309,6 +311,15 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
                struct intel_crtc *crtc = to_intel_crtc(new_crtc);
                struct intel_crtc_state *crtc_state =
                        intel_atomic_get_new_crtc_state(state, crtc);
+               struct drm_dp_mst_topology_state *topology_state;
+               u8 link_coding_cap = intel_dp_is_uhbr(crtc_state) ?
+                       DP_CAP_ANSI_128B132B : DP_CAP_ANSI_8B10B;
+
+               topology_state = 
drm_atomic_get_mst_topology_state(&state->base, mgr);
+               if (IS_ERR(topology_state))
+                       return PTR_ERR(topology_state);
+
+               drm_dp_mst_update_slots(topology_state, link_coding_cap);
 
                if (!crtc_state ||
                    !drm_atomic_crtc_needs_modeset(&crtc_state->uapi) ||
@@ -316,7 +327,6 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
                        return 0;
        }
 
-       mgr = 
&enc_to_mst(to_intel_encoder(old_conn_state->best_encoder))->primary->dp.mst_mgr;
        ret = drm_dp_atomic_release_vcpi_slots(&state->base, mgr,
                                               intel_connector->port);
 
@@ -357,6 +367,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state 
*state,
        struct intel_connector *connector =
                to_intel_connector(old_conn_state->connector);
        struct drm_i915_private *i915 = to_i915(connector->base.dev);
+       int start_slot = intel_dp_is_uhbr(old_crtc_state) ? 0 : 1;
        int ret;
 
        drm_dbg_kms(&i915->drm, "active links %d\n",
@@ -366,7 +377,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state 
*state,
 
        drm_dp_mst_reset_vcpi_slots(&intel_dp->mst_mgr, connector->port);
 
-       ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, 1);
+       ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, start_slot);
        if (ret) {
                drm_dbg_kms(&i915->drm, "failed to update payload %d\n", ret);
        }
@@ -475,6 +486,7 @@ static void intel_mst_pre_enable_dp(struct 
intel_atomic_state *state,
        struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
        struct intel_connector *connector =
                to_intel_connector(conn_state->connector);
+       int start_slot = intel_dp_is_uhbr(pipe_config) ? 0 : 1;
        int ret;
        bool first_mst_stream;
 
@@ -509,7 +521,7 @@ static void intel_mst_pre_enable_dp(struct 
intel_atomic_state *state,
 
        intel_dp->active_mst_links++;
 
-       ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, 1);
+       ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, start_slot);
 
        /*
         * Before Gen 12 this is not done as part of
-- 
2.30.2

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