drm/amd/display: don't create new dc_sink if nothing changed at detection

Signed-off-by: Samson Tam <Samson.Tam@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index ea5d5ffd552204115b587ce548650138b57a7e31..2fa521812d23bda9406485591741cd185d9bd293 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -469,6 +469,13 @@ static void link_disconnect_sink(struct dc_link *link)
        link->dpcd_sink_count = 0;
 }
 
+static void link_disconnect_remap(struct dc_sink *prev_sink, struct dc_link *link)
+{
+       dc_sink_release(link->local_sink);
+       link->local_sink = prev_sink;
+}
+
+
 static bool detect_dp(
        struct dc_link *link,
        struct display_sink_capability *sink_caps,
@@ -551,6 +558,17 @@ static bool detect_dp(
        return true;
 }
 
+static bool is_same_edid(struct dc_edid *old_edid, struct dc_edid *new_edid)
+{
+       if (old_edid->length != new_edid->length)
+               return false;
+
+       if (new_edid->length == 0)
+               return false;
+
+       return (memcmp(old_edid->raw_edid, new_edid->raw_edid, new_edid->length) == 0);
+}
+
 bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
 {
        struct dc_sink_init_data sink_init_data = { 0 };
@@ -558,9 +576,13 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
        uint8_t i;
        bool converter_disable_audio = false;
        struct audio_support *aud_support = &link->dc->res_pool->audio_support;
+       bool same_edid = false;
        enum dc_edid_status edid_status;
        struct dc_context *dc_ctx = link->ctx;
        struct dc_sink *sink = NULL;
+       struct dc_sink *prev_sink = NULL;
+       struct dpcd_caps prev_dpcd_caps;
+       bool same_dpcd = true;
        enum dc_connection_type new_connection_type = dc_connection_none;
        DC_LOGGER_INIT(link->ctx->logger);
        if (link->connector_signal == SIGNAL_TYPE_VIRTUAL)
@@ -575,6 +597,11 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
                        link->local_sink)
                return true;
 
+       prev_sink = link->local_sink;
+       if (prev_sink != NULL) {
+               dc_sink_retain(prev_sink);
+               memcpy(&prev_dpcd_caps, &link->dpcd_caps, sizeof(struct dpcd_caps));
+       }
        link_disconnect_sink(link);
 
        if (new_connection_type != dc_connection_none) {
@@ -616,14 +643,25 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
                                link,
                                &sink_caps,
                                &converter_disable_audio,
-                               aud_support, reason))
+                               aud_support, reason)) {
+                               if (prev_sink != NULL)
+                                       dc_sink_release(prev_sink);
                                return false;
+                       }
 
+                       // Check if dpcp block is the same
+                       if (prev_sink != NULL) {
+                               if (memcmp(&link->dpcd_caps, &prev_dpcd_caps, sizeof(struct dpcd_caps)))
+                                       same_dpcd = false;
+                       }
                        /* Active dongle downstream unplug */
                        if (link->type == dc_connection_active_dongle
                                        && link->dpcd_caps.sink_count.
-                                       bits.SINK_COUNT == 0)
+                                       bits.SINK_COUNT == 0) {
+                               if (prev_sink != NULL)
+                                       dc_sink_release(prev_sink);
                                return true;
+                       }
 
                        if (link->type == dc_connection_mst_branch) {
                                LINK_INFO("link=%d, mst branch is now Connected\n",
@@ -634,6 +672,8 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
                                 * pbn_per_slot value leading to exception on dc_fixpt_div()
                                 */
                                link->verified_link_cap = link->reported_link_cap;
+                               if (prev_sink != NULL)
+                                       dc_sink_release(prev_sink);
                                return false;
                        }
 
@@ -643,6 +683,8 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
                default:
                        DC_ERROR("Invalid connector type! signal:%d\n",
                                link->connector_signal);
+                       if (prev_sink != NULL)
+                               dc_sink_release(prev_sink);
                        return false;
                } /* switch() */
 
@@ -665,6 +707,8 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
                sink = dc_sink_create(&sink_init_data);
                if (!sink) {
                        DC_ERROR("Failed to create sink!\n");
+                       if (prev_sink != NULL)
+                               dc_sink_release(prev_sink);
                        return false;
                }
 
@@ -688,22 +732,33 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
                        break;
                }
 
-               if (link->connector_signal == SIGNAL_TYPE_DISPLAY_PORT &&
-                       sink_caps.transaction_type ==
-                       DDC_TRANSACTION_TYPE_I2C_OVER_AUX) {
-                       /*
-                        * TODO debug why Dell 2413 doesn't like
-                        *  two link trainings
-                        */
+               // Check if edid is the same
+               if ((prev_sink != NULL) && ((edid_status == EDID_THE_SAME) || (edid_status == EDID_OK)))
+                       same_edid = is_same_edid(&prev_sink->dc_edid, &sink->dc_edid);
 
-                       /* deal with non-mst cases */
-                       dp_hbr_verify_link_cap(link, &link->reported_link_cap);
-               }
+               // If both edid and dpcd are the same, then discard new sink and revert back to original sink
+               if ((same_edid) && (same_dpcd)) {
+                       link_disconnect_remap(prev_sink, link);
+                       sink = prev_sink;
+                       prev_sink = NULL;
+               } else {
+                       if (link->connector_signal == SIGNAL_TYPE_DISPLAY_PORT &&
+                                       sink_caps.transaction_type ==
+                                               DDC_TRANSACTION_TYPE_I2C_OVER_AUX) {
+                               /*
+                                * TODO debug why Dell 2413 doesn't like
+                                *  two link trainings
+                                */
+
+                               /* deal with non-mst cases */
+                               dp_hbr_verify_link_cap(link, &link->reported_link_cap);
+                       }
 
-               /* HDMI-DVI Dongle */
-               if (sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A &&
-                               !sink->edid_caps.edid_hdmi)
-                       sink->sink_signal = SIGNAL_TYPE_DVI_SINGLE_LINK;
+                       /* HDMI-DVI Dongle */
+                       if (sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A &&
+                                       !sink->edid_caps.edid_hdmi)
+                               sink->sink_signal = SIGNAL_TYPE_DVI_SINGLE_LINK;
+               }
 
                /* Connectivity log: detection */
                for (i = 0; i < sink->dc_edid.length / EDID_BLOCK_SIZE; i++) {
@@ -762,10 +817,14 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
                sink_caps.signal = SIGNAL_TYPE_NONE;
        }
 
-       LINK_INFO("link=%d, dc_sink_in=%p is now %s\n",
+       LINK_INFO("link=%d, dc_sink_in=%p is now %s prev_sink=%p dpcd same=%d edid same=%d\n",
                link->link_index, sink,
                (sink_caps.signal == SIGNAL_TYPE_NONE ?
-                       "Disconnected":"Connected"));
+                       "Disconnected":"Connected"), prev_sink,
+                       same_dpcd, same_edid);
+
+       if (prev_sink != NULL)
+               dc_sink_release(prev_sink);
 
        return true;
 }