drm/amd/display: fix decide_link_settings

Signed-off-by: Ding Wang <Ding.Wang@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@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.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index ad1b905..de05ad0 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -308,10 +308,8 @@ static void set_preferred_link_settings(struct dc *dc,
 {
        struct core_link *core_link = DC_LINK_TO_CORE(link);
 
-       core_link->public.verified_link_cap.lane_count =
-                               link_setting->lane_count;
-       core_link->public.verified_link_cap.link_rate =
-                               link_setting->link_rate;
+       core_link->public.preferred_link_setting =
+                               *link_setting;
        dp_retrain_link_dp_test(core_link, link_setting, false);
 }
 

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 445cd22..e90b3eb 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -33,32 +33,6 @@ enum {
        LINK_TRAINING_MAX_CR_RETRY = 100
 };
 
-static const struct dc_link_settings link_training_fallback_table[] = {
-/* 4320 Mbytes/sec*/
-{ LANE_COUNT_FOUR, LINK_RATE_HIGH3, LINK_SPREAD_DISABLED },
-/* 2160 Mbytes/sec*/
-{ LANE_COUNT_FOUR, LINK_RATE_HIGH2, LINK_SPREAD_DISABLED },
-/* 1080 Mbytes/sec*/
-{ LANE_COUNT_FOUR, LINK_RATE_HIGH, LINK_SPREAD_DISABLED },
-/* 648 Mbytes/sec*/
-{ LANE_COUNT_FOUR, LINK_RATE_LOW, LINK_SPREAD_DISABLED },
-/* 2160 Mbytes/sec*/
-{ LANE_COUNT_TWO, LINK_RATE_HIGH3, LINK_SPREAD_DISABLED },
-/* 1080 Mbytes/sec*/
-{ LANE_COUNT_TWO, LINK_RATE_HIGH2, LINK_SPREAD_DISABLED },
-/* 540 Mbytes/sec*/
-{ LANE_COUNT_TWO, LINK_RATE_HIGH, LINK_SPREAD_DISABLED },
-/* 324 Mbytes/sec*/
-{ LANE_COUNT_TWO, LINK_RATE_LOW, LINK_SPREAD_DISABLED },
-/* 1080 Mbytes/sec*/
-{ LANE_COUNT_ONE, LINK_RATE_HIGH3, LINK_SPREAD_DISABLED },
-/* 540 Mbytes/sec*/
-{ LANE_COUNT_ONE, LINK_RATE_HIGH2, LINK_SPREAD_DISABLED },
-/* 270 Mbytes/sec*/
-{ LANE_COUNT_ONE, LINK_RATE_HIGH, LINK_SPREAD_DISABLED },
-/* 162 Mbytes/sec*/
-{ LANE_COUNT_ONE, LINK_RATE_LOW, LINK_SPREAD_DISABLED } };
-
 static void wait_for_training_aux_rd_interval(
        struct core_link* link,
        uint32_t default_wait_in_micro_secs)
@@ -1053,29 +1027,6 @@ bool perform_link_training_with_retries(
        return false;
 }
 
-/*TODO add more check to see if link support request link configuration */
-static bool is_link_setting_supported(
-       const struct dc_link_settings *link_setting,
-       const struct dc_link_settings *max_link_setting)
-{
-       if (link_setting->lane_count > max_link_setting->lane_count ||
-               link_setting->link_rate > max_link_setting->link_rate)
-               return false;
-       return true;
-}
-
-static const uint32_t get_link_training_fallback_table_len(
-       struct core_link *link)
-{
-       return ARRAY_SIZE(link_training_fallback_table);
-}
-
-static const struct dc_link_settings *get_link_training_fallback_table(
-       struct core_link *link, uint32_t i)
-{
-       return &link_training_fallback_table[i];
-}
-
 static struct dc_link_settings get_max_link_cap(struct core_link *link)
 {
        /* Set Default link settings */
@@ -1284,6 +1235,32 @@ enum dc_link_rate reduce_link_rate(enum dc_link_rate link_rate)
        }
 }
 
+enum dc_lane_count increase_lane_count(enum dc_lane_count lane_count)
+{
+       switch (lane_count) {
+       case LANE_COUNT_ONE:
+               return LANE_COUNT_TWO;
+       case LANE_COUNT_TWO:
+               return LANE_COUNT_FOUR;
+       default:
+               return LANE_COUNT_UNKNOWN;
+       }
+}
+
+enum dc_link_rate increase_link_rate(enum dc_link_rate link_rate)
+{
+       switch (link_rate) {
+       case LINK_RATE_LOW:
+               return LINK_RATE_HIGH;
+       case LINK_RATE_HIGH:
+               return LINK_RATE_HIGH2;
+       case LINK_RATE_HIGH2:
+               return LINK_RATE_HIGH3;
+       default:
+               return LINK_RATE_UNKNOWN;
+       }
+}
+
 /*
  * function: set link rate and lane count fallback based
  * on current link setting and last link training result
@@ -1463,57 +1440,60 @@ void decide_link_settings(struct core_stream *stream,
        struct dc_link_settings *link_setting)
 {
 
-       const struct dc_link_settings *cur_ls;
+       struct dc_link_settings initial_link_setting = {
+               LANE_COUNT_ONE, LINK_RATE_LOW, LINK_SPREAD_DISABLED};
+       struct dc_link_settings current_link_setting =
+                       initial_link_setting;
        struct core_link* link;
        uint32_t req_bw;
        uint32_t link_bw;
-       uint32_t i;
 
        req_bw = bandwidth_in_kbps_from_timing(
                        &stream->public.timing);
 
+       link = stream->sink->link;
+
        /* if preferred is specified through AMDDP, use it, if it's enough
         * to drive the mode
         */
-       link = stream->sink->link;
-
-       if ((link->public.reported_link_cap.lane_count != LANE_COUNT_UNKNOWN) &&
-               (link->public.reported_link_cap.link_rate <=
-                               link->public.verified_link_cap.link_rate)) {
+       if (link->public.preferred_link_setting.lane_count !=
+                       LANE_COUNT_UNKNOWN &&
+                       link->public.preferred_link_setting.link_rate !=
+                                       LINK_RATE_UNKNOWN) {
+               *link_setting =  link->public.preferred_link_setting;
+               return;
+       }
 
+    /* search for the minimum link setting that:
+     * 1. is supported according to the link training result
+     * 2. could support the b/w requested by the timing
+     */
+       while (current_link_setting.link_rate <=
+                       link->public.max_link_setting.link_rate) {
                link_bw = bandwidth_in_kbps_from_link_settings(
-                               &link->public.reported_link_cap);
-
-               if (req_bw < link_bw) {
-                       *link_setting = link->public.reported_link_cap;
+                               &current_link_setting);
+               if (req_bw <= link_bw) {
+                       *link_setting = current_link_setting;
                        return;
                }
-       }
 
-       /* search for first suitable setting for the requested
-        * bandwidth
-        */
-       for (i = 0; i < get_link_training_fallback_table_len(link); i++) {
-
-               cur_ls = get_link_training_fallback_table(link, i);
-
-               link_bw =
-                               bandwidth_in_kbps_from_link_settings(
-                               cur_ls);
-
-               if (req_bw < link_bw) {
-                       if (is_link_setting_supported(
-                               cur_ls,
-                               &link->public.max_link_setting)) {
-                               *link_setting = *cur_ls;
-                               return;
-                       }
+               if (current_link_setting.lane_count <
+                               link->public.max_link_setting.lane_count) {
+                       current_link_setting.lane_count =
+                                       increase_lane_count(
+                                                       current_link_setting.lane_count);
+               } else {
+                       current_link_setting.link_rate =
+                                       increase_link_rate(
+                                                       current_link_setting.link_rate);
+                       current_link_setting.lane_count =
+                                       initial_link_setting.lane_count;
                }
        }
 
        BREAK_TO_DEBUGGER();
        ASSERT(link->public.verified_link_cap.lane_count !=
-               LANE_COUNT_UNKNOWN);
+                       LANE_COUNT_UNKNOWN);
 
        *link_setting = link->public.verified_link_cap;
 }

diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index 6172708..ee04c35 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -674,6 +674,7 @@ struct dc_link {
        struct dc_link_settings max_link_setting;
        struct dc_link_settings cur_link_settings;
        struct dc_lane_settings cur_lane_setting;
+       struct dc_link_settings preferred_link_setting;
 
        uint8_t ddc_hw_inst;