drm/amd/display: configure lttpr mode

[Description]
1-Grant extended timeout request. Done once after detection
2-Configure lttpr mode based on lttpr support before LT
3-Account for lttpr cap when determining max link settings

Signed-off-by: abdoulaye berthe <abdoulaye.berthe@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 1e4480f..94d5a0a 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
@@ -1057,6 +1057,26 @@ static void initialize_training_settings(
                lt_settings->enhanced_framing = 1;
 }
 
+static void configure_lttpr_mode(struct dc_link *link)
+{
+       /* aux timeout is already set to extended */
+       /* RESET/SET lttpr mode to enable non transparent mode */
+       enum lttpr_mode repeater_mode = phy_repeater_mode_transparent;
+
+       core_link_write_dpcd(link,
+                       DP_PHY_REPEATER_MODE,
+                       (uint8_t *)&repeater_mode,
+                       sizeof(repeater_mode));
+
+       if (!link->is_lttpr_mode_transparent) {
+               repeater_mode = phy_repeater_mode_non_transparent;
+               core_link_write_dpcd(link,
+                               DP_PHY_REPEATER_MODE,
+                               (uint8_t *)&repeater_mode,
+                               sizeof(repeater_mode));
+       }
+}
+
 static void print_status_message(
        struct dc_link *link,
        const struct link_training_settings *lt_settings,
@@ -1210,6 +1230,9 @@ enum link_training_result dc_link_dp_perform_link_training(
        dp_set_fec_ready(link, fec_enable);
 #endif
 
+       /* Configure lttpr mode */
+       if (!link->is_lttpr_mode_transparent)
+               configure_lttpr_mode(link);
 
        /* 2. perform link training (set link training done
         *  to false is done as well)
@@ -1426,6 +1449,17 @@ static struct dc_link_settings get_max_link_cap(struct dc_link *link)
                        max_link_cap.link_spread)
                max_link_cap.link_spread =
                                link->reported_link_cap.link_spread;
+       /*
+        * account for lttpr repeaters cap
+        * notes: repeaters do not snoop in the DPRX Capabilities addresses (3.6.3).
+        */
+       if (!link->is_lttpr_mode_transparent) {
+               if (link->dpcd_caps.lttpr_caps.max_lane_count < max_link_cap.lane_count)
+                       max_link_cap.lane_count = link->dpcd_caps.lttpr_caps.max_lane_count;
+
+               if (link->dpcd_caps.lttpr_caps.max_link_rate < max_link_cap.link_rate)
+                       max_link_cap.link_rate = link->dpcd_caps.lttpr_caps.max_link_rate;
+       }
        return max_link_cap;
 }
 
@@ -1571,6 +1605,13 @@ bool dp_verify_link_cap(
 
        max_link_cap = get_max_link_cap(link);
 
+       /* Grant extended timeout request */
+       if (!link->is_lttpr_mode_transparent && link->dpcd_caps.lttpr_caps.max_ext_timeout > 0) {
+               uint8_t grant = link->dpcd_caps.lttpr_caps.max_ext_timeout & 0x80;
+
+               core_link_write_dpcd(link, DP_PHY_REPEATER_EXTENDED_WAIT_TIMEOUT, &grant, sizeof(grant));
+       }
+
        /* TODO implement override and monitor patch later */
 
        /* try to train the link from high to low to
@@ -2759,6 +2800,7 @@ static bool retrieve_link_cap(struct dc_link *link)
        /* Set default timeout to 3.2ms and read LTTPR capabilities */
        bool ext_timeout_support = link->dc->caps.extended_aux_timeout_support &&
                        !link->dc->config.disable_extended_timeout_support;
+
        link->is_lttpr_mode_transparent = true;
 
        if (ext_timeout_support) {