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<pre>Hi Lyude,<br><br>Jerry is busy these few weeks so I will be taking a look at this. I added the start/total slots to the mst_state and am updating them in atomic_check.<br><br>Also ignore the V2 "<font size="2"><span style="font-size:11pt">* Remove get_mst_link_encoding_cap</span></font>" I got a bit lost in trying to figure out the patch layout that was sent before.<br><br><br>Thanks,<br>Bhawan<br></pre>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com><br>
<b>Sent:</b> October 12, 2021 5:58 PM<br>
<b>To:</b> Zuo, Jerry <Jerry.Zuo@amd.com>; dri-devel@lists.freedesktop.org <dri-devel@lists.freedesktop.org>; lyude@redhat.com <lyude@redhat.com><br>
<b>Cc:</b> Wentland, Harry <Harry.Wentland@amd.com>; Lin, Wayne <Wayne.Lin@amd.com>; Kazlauskas, Nicholas <Nicholas.Kazlauskas@amd.com>; Lakha, Bhawanpreet <Bhawanpreet.Lakha@amd.com><br>
<b>Subject:</b> [PATCH] drm: Update MST First Link Slot Information Based on Encoding Format</font>
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<div class="PlainText">8b/10b encoding format requires to reserve the first slot for<br>
recording metadata. Real data transmission starts from the second slot,<br>
with a total of available 63 slots available.<br>
<br>
In 128b/132b encoding format, metadata is transmitted separately<br>
in LLCP packet before MTP. Real data transmission starts from<br>
the first slot, with a total of 64 slots available.<br>
<br>
v2:<br>
* Remove get_mst_link_encoding_cap<br>
* Move total/start slots to mst_state, and copy it to mst_mgr in<br>
atomic_check<br>
<br>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com><br>
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com><br>
---<br>
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 28 +++++++++++++++<br>
 drivers/gpu/drm/drm_dp_mst_topology.c         | 35 +++++++++++++++----<br>
 include/drm/drm_dp_mst_helper.h               | 13 +++++++<br>
 3 files changed, 69 insertions(+), 7 deletions(-)<br>
<br>
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c<br>
index 5020f2d36fe1..4ad50eb0091a 100644<br>
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c<br>
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c<br>
@@ -10612,6 +10612,8 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,<br>
 #if defined(CONFIG_DRM_AMD_DC_DCN)<br>
         struct dsc_mst_fairness_vars vars[MAX_PIPES];<br>
 #endif<br>
+       struct drm_dp_mst_topology_state *mst_state;<br>
+       struct drm_dp_mst_topology_mgr *mgr;<br>
 <br>
         trace_amdgpu_dm_atomic_check_begin(state);<br>
 <br>
@@ -10819,6 +10821,32 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,<br>
                 lock_and_validation_needed = true;<br>
         }<br>
 <br>
+#if defined(CONFIG_DRM_AMD_DC_DCN)<br>
+       for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {<br>
+               struct amdgpu_dm_connector *aconnector;<br>
+               struct drm_connector *connector;<br>
+               struct drm_connector_list_iter iter;<br>
+               u8 link_coding_cap;<br>
+<br>
+               if (!mgr->mst_state )<br>
+                       continue;<br>
+<br>
+               drm_connector_list_iter_begin(dev, &iter);<br>
+               drm_for_each_connector_iter(connector, &iter) {<br>
+                       int id = connector->index;<br>
+<br>
+                       if (id == mst_state->mgr->conn_base_id) {<br>
+                               aconnector = to_amdgpu_dm_connector(connector);<br>
+                               link_coding_cap = dc_link_dp_mst_decide_link_encoding_format(aconnector->dc_link);<br>
+                               drm_dp_mst_update_coding_cap(mst_state, link_coding_cap);<br>
+<br>
+                               break;<br>
+                       }<br>
+               }<br>
+               drm_connector_list_iter_end(&iter);<br>
+<br>
+       }<br>
+#endif<br>
         /**<br>
          * Streams and planes are reset when there are changes that affect<br>
          * bandwidth. Anything that affects bandwidth needs to go through<br>
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c<br>
index ad0795afc21c..fb5c47c4cb2e 100644<br>
--- a/drivers/gpu/drm/drm_dp_mst_topology.c<br>
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c<br>
@@ -3368,7 +3368,7 @@ int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr)<br>
         struct drm_dp_payload req_payload;<br>
         struct drm_dp_mst_port *port;<br>
         int i, j;<br>
-       int cur_slots = 1;<br>
+       int cur_slots = mgr->start_slot;<br>
         bool skip;<br>
 <br>
         mutex_lock(&mgr->payload_lock);<br>
@@ -4321,7 +4321,7 @@ int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,<br>
         num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);<br>
 <br>
         /* max. time slots - one slot for MTP header */<br>
-       if (num_slots > 63)<br>
+       if (num_slots > mgr->total_avail_slots)<br>
                 return -ENOSPC;<br>
         return num_slots;<br>
 }<br>
@@ -4333,7 +4333,7 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,<br>
         int ret;<br>
 <br>
         /* max. time slots - one slot for MTP header */<br>
-       if (slots > 63)<br>
+       if (slots > mgr->total_avail_slots)<br>
                 return -ENOSPC;<br>
 <br>
         vcpi->pbn = pbn;<br>
@@ -4507,6 +4507,18 @@ int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,<br>
 }<br>
 EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);<br>
 <br>
+void drm_dp_mst_update_coding_cap(struct drm_dp_mst_topology_state *mst_state, uint8_t link_coding_cap)<br>
+{<br>
+       if (link_coding_cap == DP_CAP_ANSI_128B132B) {<br>
+               mst_state->total_avail_slots = 64;<br>
+               mst_state->start_slot = 0;<br>
+       }<br>
+<br>
+       DRM_DEBUG_KMS("%s coding format on mgr 0x%p\n",<br>
+                       (link_coding_cap == DP_CAP_ANSI_128B132B) ? "128b/132b":"8b/10b", mst_state->mgr);<br>
+}<br>
+EXPORT_SYMBOL(drm_dp_mst_update_coding_cap);<br>
+<br>
 /**<br>
  * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel<br>
  * @mgr: manager for this port<br>
@@ -4538,8 +4550,8 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,<br>
 <br>
         ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn, slots);<br>
         if (ret) {<br>
-               drm_dbg_kms(mgr->dev, "failed to init vcpi slots=%d max=63 ret=%d\n",<br>
-                           DIV_ROUND_UP(pbn, mgr->pbn_div), ret);<br>
+               drm_dbg_kms(mgr->dev, "failed to init vcpi slots=%d max=%d ret=%d\n",<br>
+                           DIV_ROUND_UP(pbn, mgr->pbn_div), mgr->total_avail_slots, ret);<br>
                 drm_dp_mst_topology_put_port(port);<br>
                 goto out;<br>
         }<br>
@@ -5226,7 +5238,7 @@ drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,<br>
                                          struct drm_dp_mst_topology_state *mst_state)<br>
 {<br>
         struct drm_dp_vcpi_allocation *vcpi;<br>
-       int avail_slots = 63, payload_count = 0;<br>
+       int avail_slots = mgr->total_avail_slots, payload_count = 0;<br>
 <br>
         list_for_each_entry(vcpi, &mst_state->vcpis, next) {<br>
                 /* Releasing VCPI is always OK-even if the port is gone */<br>
@@ -5255,7 +5267,7 @@ drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,<br>
                 }<br>
         }<br>
         drm_dbg_atomic(mgr->dev, "[MST MGR:%p] mst state %p VCPI avail=%d used=%d\n",<br>
-                      mgr, mst_state, avail_slots, 63 - avail_slots);<br>
+                      mgr, mst_state, avail_slots, mgr->total_avail_slots - avail_slots);<br>
 <br>
         return 0;<br>
 }<br>
@@ -5421,6 +5433,10 @@ int drm_dp_mst_atomic_check(struct drm_atomic_state *state)<br>
                         break;<br>
 <br>
                 mutex_lock(&mgr->lock);<br>
+<br>
+               mgr->start_slot = mst_state->start_slot;<br>
+               mgr->total_avail_slots = mst_state->total_avail_slots;<br>
+<br>
                 ret = drm_dp_mst_atomic_check_mstb_bw_limit(mgr->mst_primary,<br>
                                                             mst_state);<br>
                 mutex_unlock(&mgr->lock);<br>
@@ -5527,11 +5543,16 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,<br>
         if (!mgr->proposed_vcpis)<br>
                 return -ENOMEM;<br>
         set_bit(0, &mgr->payload_mask);<br>
+       mgr->total_avail_slots = 63;<br>
+       mgr->start_slot = 1;<br>
 <br>
         mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);<br>
         if (mst_state == NULL)<br>
                 return -ENOMEM;<br>
 <br>
+       mst_state->total_avail_slots = 63;<br>
+       mst_state->start_slot = 1;<br>
+<br>
         mst_state->mgr = mgr;<br>
         INIT_LIST_HEAD(&mst_state->vcpis);<br>
 <br>
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h<br>
index ddb9231d0309..f8152dfb34ed 100644<br>
--- a/include/drm/drm_dp_mst_helper.h<br>
+++ b/include/drm/drm_dp_mst_helper.h<br>
@@ -554,6 +554,8 @@ struct drm_dp_mst_topology_state {<br>
         struct drm_private_state base;<br>
         struct list_head vcpis;<br>
         struct drm_dp_mst_topology_mgr *mgr;<br>
+       u8 total_avail_slots;<br>
+       u8 start_slot;<br>
 };<br>
 <br>
 #define to_dp_mst_topology_mgr(x) container_of(x, struct drm_dp_mst_topology_mgr, base)<br>
@@ -661,6 +663,16 @@ struct drm_dp_mst_topology_mgr {<br>
          */<br>
         int pbn_div;<br>
 <br>
+       /**<br>
+        * @total_avail_slots: 63 for 8b/10b, 64 for 128/132b<br>
+        */<br>
+       u8 total_avail_slots;<br>
+<br>
+       /**<br>
+        * @start_slot: 1 for 8b/10b, 0 for 128/132b<br>
+        */<br>
+       u8 start_slot;<br>
+<br>
         /**<br>
          * @funcs: Atomic helper callbacks<br>
          */<br>
@@ -806,6 +818,7 @@ int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp<br>
 <br>
 void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);<br>
 <br>
+void drm_dp_mst_update_coding_cap(struct drm_dp_mst_topology_state *mst_state, uint8_t link_coding_cap);<br>
 <br>
 void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,<br>
                                 struct drm_dp_mst_port *port);<br>
-- <br>
2.25.1<br>
<br>
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