[PATCH] drm: Update MST First Link Slot Information Based on Encoding Format

Lakha, Bhawanpreet Bhawanpreet.Lakha at amd.com
Tue Oct 12 22:02:41 UTC 2021


[AMD Official Use Only]


Hi Lyude,

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.

Also ignore the V2 "* Remove get_mst_link_encoding_cap" I got a bit lost in trying to figure out the patch layout that was sent before.


Thanks,
Bhawan

________________________________
From: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
Sent: October 12, 2021 5:58 PM
To: Zuo, Jerry <Jerry.Zuo at amd.com>; dri-devel at lists.freedesktop.org <dri-devel at lists.freedesktop.org>; lyude at redhat.com <lyude at redhat.com>
Cc: Wentland, Harry <Harry.Wentland at amd.com>; Lin, Wayne <Wayne.Lin at amd.com>; Kazlauskas, Nicholas <Nicholas.Kazlauskas at amd.com>; Lakha, Bhawanpreet <Bhawanpreet.Lakha at amd.com>
Subject: [PATCH] drm: Update MST First Link Slot Information Based on Encoding Format

8b/10b encoding format requires to reserve the first slot for
recording metadata. Real data transmission starts from the second slot,
with a total of available 63 slots available.

In 128b/132b encoding format, metadata is transmitted separately
in LLCP packet before MTP. Real data transmission starts from
the first slot, with a total of 64 slots available.

v2:
* Remove get_mst_link_encoding_cap
* Move total/start slots to mst_state, and copy it to mst_mgr in
atomic_check

Signed-off-by: Fangzhi Zuo <Jerry.Zuo at amd.com>
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 28 +++++++++++++++
 drivers/gpu/drm/drm_dp_mst_topology.c         | 35 +++++++++++++++----
 include/drm/drm_dp_mst_helper.h               | 13 +++++++
 3 files changed, 69 insertions(+), 7 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 5020f2d36fe1..4ad50eb0091a 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -10612,6 +10612,8 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 #if defined(CONFIG_DRM_AMD_DC_DCN)
         struct dsc_mst_fairness_vars vars[MAX_PIPES];
 #endif
+       struct drm_dp_mst_topology_state *mst_state;
+       struct drm_dp_mst_topology_mgr *mgr;

         trace_amdgpu_dm_atomic_check_begin(state);

@@ -10819,6 +10821,32 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
                 lock_and_validation_needed = true;
         }

+#if defined(CONFIG_DRM_AMD_DC_DCN)
+       for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
+               struct amdgpu_dm_connector *aconnector;
+               struct drm_connector *connector;
+               struct drm_connector_list_iter iter;
+               u8 link_coding_cap;
+
+               if (!mgr->mst_state )
+                       continue;
+
+               drm_connector_list_iter_begin(dev, &iter);
+               drm_for_each_connector_iter(connector, &iter) {
+                       int id = connector->index;
+
+                       if (id == mst_state->mgr->conn_base_id) {
+                               aconnector = to_amdgpu_dm_connector(connector);
+                               link_coding_cap = dc_link_dp_mst_decide_link_encoding_format(aconnector->dc_link);
+                               drm_dp_mst_update_coding_cap(mst_state, link_coding_cap);
+
+                               break;
+                       }
+               }
+               drm_connector_list_iter_end(&iter);
+
+       }
+#endif
         /**
          * Streams and planes are reset when there are changes that affect
          * bandwidth. Anything that affects bandwidth needs to go through
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index ad0795afc21c..fb5c47c4cb2e 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3368,7 +3368,7 @@ int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr)
         struct drm_dp_payload req_payload;
         struct drm_dp_mst_port *port;
         int i, j;
-       int cur_slots = 1;
+       int cur_slots = mgr->start_slot;
         bool skip;

         mutex_lock(&mgr->payload_lock);
@@ -4321,7 +4321,7 @@ int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
         num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);

         /* max. time slots - one slot for MTP header */
-       if (num_slots > 63)
+       if (num_slots > mgr->total_avail_slots)
                 return -ENOSPC;
         return num_slots;
 }
@@ -4333,7 +4333,7 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
         int ret;

         /* max. time slots - one slot for MTP header */
-       if (slots > 63)
+       if (slots > mgr->total_avail_slots)
                 return -ENOSPC;

         vcpi->pbn = pbn;
@@ -4507,6 +4507,18 @@ int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 }
 EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);

+void drm_dp_mst_update_coding_cap(struct drm_dp_mst_topology_state *mst_state, uint8_t link_coding_cap)
+{
+       if (link_coding_cap == DP_CAP_ANSI_128B132B) {
+               mst_state->total_avail_slots = 64;
+               mst_state->start_slot = 0;
+       }
+
+       DRM_DEBUG_KMS("%s coding format on mgr 0x%p\n",
+                       (link_coding_cap == DP_CAP_ANSI_128B132B) ? "128b/132b":"8b/10b", mst_state->mgr);
+}
+EXPORT_SYMBOL(drm_dp_mst_update_coding_cap);
+
 /**
  * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel
  * @mgr: manager for this port
@@ -4538,8 +4550,8 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,

         ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn, slots);
         if (ret) {
-               drm_dbg_kms(mgr->dev, "failed to init vcpi slots=%d max=63 ret=%d\n",
-                           DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
+               drm_dbg_kms(mgr->dev, "failed to init vcpi slots=%d max=%d ret=%d\n",
+                           DIV_ROUND_UP(pbn, mgr->pbn_div), mgr->total_avail_slots, ret);
                 drm_dp_mst_topology_put_port(port);
                 goto out;
         }
@@ -5226,7 +5238,7 @@ drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,
                                          struct drm_dp_mst_topology_state *mst_state)
 {
         struct drm_dp_vcpi_allocation *vcpi;
-       int avail_slots = 63, payload_count = 0;
+       int avail_slots = mgr->total_avail_slots, payload_count = 0;

         list_for_each_entry(vcpi, &mst_state->vcpis, next) {
                 /* Releasing VCPI is always OK-even if the port is gone */
@@ -5255,7 +5267,7 @@ drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,
                 }
         }
         drm_dbg_atomic(mgr->dev, "[MST MGR:%p] mst state %p VCPI avail=%d used=%d\n",
-                      mgr, mst_state, avail_slots, 63 - avail_slots);
+                      mgr, mst_state, avail_slots, mgr->total_avail_slots - avail_slots);

         return 0;
 }
@@ -5421,6 +5433,10 @@ int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
                         break;

                 mutex_lock(&mgr->lock);
+
+               mgr->start_slot = mst_state->start_slot;
+               mgr->total_avail_slots = mst_state->total_avail_slots;
+
                 ret = drm_dp_mst_atomic_check_mstb_bw_limit(mgr->mst_primary,
                                                             mst_state);
                 mutex_unlock(&mgr->lock);
@@ -5527,11 +5543,16 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
         if (!mgr->proposed_vcpis)
                 return -ENOMEM;
         set_bit(0, &mgr->payload_mask);
+       mgr->total_avail_slots = 63;
+       mgr->start_slot = 1;

         mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
         if (mst_state == NULL)
                 return -ENOMEM;

+       mst_state->total_avail_slots = 63;
+       mst_state->start_slot = 1;
+
         mst_state->mgr = mgr;
         INIT_LIST_HEAD(&mst_state->vcpis);

diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index ddb9231d0309..f8152dfb34ed 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -554,6 +554,8 @@ struct drm_dp_mst_topology_state {
         struct drm_private_state base;
         struct list_head vcpis;
         struct drm_dp_mst_topology_mgr *mgr;
+       u8 total_avail_slots;
+       u8 start_slot;
 };

 #define to_dp_mst_topology_mgr(x) container_of(x, struct drm_dp_mst_topology_mgr, base)
@@ -661,6 +663,16 @@ struct drm_dp_mst_topology_mgr {
          */
         int pbn_div;

+       /**
+        * @total_avail_slots: 63 for 8b/10b, 64 for 128/132b
+        */
+       u8 total_avail_slots;
+
+       /**
+        * @start_slot: 1 for 8b/10b, 0 for 128/132b
+        */
+       u8 start_slot;
+
         /**
          * @funcs: Atomic helper callbacks
          */
@@ -806,6 +818,7 @@ int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp

 void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);

+void drm_dp_mst_update_coding_cap(struct drm_dp_mst_topology_state *mst_state, uint8_t link_coding_cap);

 void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
                                 struct drm_dp_mst_port *port);
--
2.25.1

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