drm/msm/dp: reduce link rate if failed at link training 1

Reduce link rate and re start link training if link training 1
failed due to loss of clock recovery done to fix Link Layer
CTS case 4.3.1.7.  Also only update voltage and pre-emphasis
swing level after link training started to fix Link Layer CTS
case 4.3.1.6.

Changes in V2:
-- replaced cr_status with link_status[DP_LINK_STATUS_SIZE]
-- replaced dp_ctrl_any_lane_cr_done() with dp_ctrl_colco_recovery_any_ok()
-- replaced dp_ctrl_any_ane_cr_lose() with !drm_dp_clock_recovery_ok()

Changes in V3:
-- return failed if lane_count <= 1

Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/1628196295-7382-3-git-send-email-khsieh@codeaurora.org
[remove unused cr_status variable]
Signed-off-by: Rob Clark <robdclark@chromium.org>

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index d2569da..45b5c34 100644 (file)
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -81,13 +81,6 @@ struct dp_ctrl_private {
        struct completion video_comp;
 };
 
-struct dp_cr_status {
-       u8 lane_0_1;
-       u8 lane_2_3;
-};
-
-#define DP_LANE0_1_CR_DONE     0x11
-
 static int dp_aux_link_configure(struct drm_dp_aux *aux,
                                        struct dp_link_info *link)
 {
@@ -1080,7 +1073,7 @@ static int dp_ctrl_read_link_status(struct dp_ctrl_private *ctrl,
 }
 
 static int dp_ctrl_link_train_1(struct dp_ctrl_private *ctrl,
-               struct dp_cr_status *cr, int *training_step)
+                       int *training_step)
 {
        int tries, old_v_level, ret = 0;
        u8 link_status[DP_LINK_STATUS_SIZE];
@@ -1109,9 +1102,6 @@ static int dp_ctrl_link_train_1(struct dp_ctrl_private *ctrl,
                if (ret)
                        return ret;
 
-               cr->lane_0_1 = link_status[0];
-               cr->lane_2_3 = link_status[1];
-
                if (drm_dp_clock_recovery_ok(link_status,
                        ctrl->link->link_params.num_lanes)) {
                        return 0;
@@ -1188,7 +1178,7 @@ static void dp_ctrl_clear_training_pattern(struct dp_ctrl_private *ctrl)
 }
 
 static int dp_ctrl_link_train_2(struct dp_ctrl_private *ctrl,
-               struct dp_cr_status *cr, int *training_step)
+                       int *training_step)
 {
        int tries = 0, ret = 0;
        char pattern;
@@ -1204,10 +1194,6 @@ static int dp_ctrl_link_train_2(struct dp_ctrl_private *ctrl,
        else
                pattern = DP_TRAINING_PATTERN_2;
 
-       ret = dp_ctrl_update_vx_px(ctrl);
-       if (ret)
-               return ret;
-
        ret = dp_catalog_ctrl_set_pattern(ctrl->catalog, pattern);
        if (ret)
                return ret;
@@ -1220,8 +1206,6 @@ static int dp_ctrl_link_train_2(struct dp_ctrl_private *ctrl,
                ret = dp_ctrl_read_link_status(ctrl, link_status);
                if (ret)
                        return ret;
-               cr->lane_0_1 = link_status[0];
-               cr->lane_2_3 = link_status[1];
 
                if (drm_dp_channel_eq_ok(link_status,
                        ctrl->link->link_params.num_lanes)) {
@@ -1241,7 +1225,7 @@ static int dp_ctrl_link_train_2(struct dp_ctrl_private *ctrl,
 static int dp_ctrl_reinitialize_mainlink(struct dp_ctrl_private *ctrl);
 
 static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
-               struct dp_cr_status *cr, int *training_step)
+                       int *training_step)
 {
        int ret = 0;
        u8 encoding = DP_SET_ANSI_8B10B;
@@ -1257,7 +1241,7 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
        drm_dp_dpcd_write(ctrl->aux, DP_MAIN_LINK_CHANNEL_CODING_SET,
                                &encoding, 1);
 
-       ret = dp_ctrl_link_train_1(ctrl, cr, training_step);
+       ret = dp_ctrl_link_train_1(ctrl, training_step);
        if (ret) {
                DRM_ERROR("link training #1 failed. ret=%d\n", ret);
                goto end;
@@ -1266,7 +1250,7 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
        /* print success info as this is a result of user initiated action */
        DRM_DEBUG_DP("link training #1 successful\n");
 
-       ret = dp_ctrl_link_train_2(ctrl, cr, training_step);
+       ret = dp_ctrl_link_train_2(ctrl, training_step);
        if (ret) {
                DRM_ERROR("link training #2 failed. ret=%d\n", ret);
                goto end;
@@ -1282,7 +1266,7 @@ end:
 }
 
 static int dp_ctrl_setup_main_link(struct dp_ctrl_private *ctrl,
-               struct dp_cr_status *cr, int *training_step)
+                       int *training_step)
 {
        int ret = 0;
 
@@ -1297,7 +1281,7 @@ static int dp_ctrl_setup_main_link(struct dp_ctrl_private *ctrl,
         * a link training pattern, we have to first do soft reset.
         */
 
-       ret = dp_ctrl_link_train(ctrl, cr, training_step);
+       ret = dp_ctrl_link_train(ctrl, training_step);
 
        return ret;
 }
@@ -1495,14 +1479,13 @@ static int dp_ctrl_deinitialize_mainlink(struct dp_ctrl_private *ctrl)
 static int dp_ctrl_link_maintenance(struct dp_ctrl_private *ctrl)
 {
        int ret = 0;
-       struct dp_cr_status cr;
        int training_step = DP_TRAINING_NONE;
 
        dp_ctrl_push_idle(&ctrl->dp_ctrl);
 
        ctrl->dp_ctrl.pixel_rate = ctrl->panel->dp_mode.drm_mode.clock;
 
-       ret = dp_ctrl_setup_main_link(ctrl, &cr, &training_step);
+       ret = dp_ctrl_setup_main_link(ctrl, &training_step);
        if (ret)
                goto end;
 
@@ -1633,6 +1616,25 @@ void dp_ctrl_handle_sink_request(struct dp_ctrl *dp_ctrl)
        }
 }
 
+static bool dp_ctrl_clock_recovery_any_ok(
+                       const u8 link_status[DP_LINK_STATUS_SIZE],
+                       int lane_count)
+{
+       int reduced_cnt;
+
+       if (lane_count <= 1)
+               return false;
+
+       /*
+        * only interested in the lane number after reduced
+        * lane_count = 4, then only interested in 2 lanes
+        * lane_count = 2, then only interested in 1 lane
+        */
+       reduced_cnt = lane_count >> 1;
+
+       return drm_dp_clock_recovery_ok(link_status, reduced_cnt);
+}
+
 int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
 {
        int rc = 0;
@@ -1640,7 +1642,7 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
        u32 rate = 0;
        int link_train_max_retries = 5;
        u32 const phy_cts_pixel_clk_khz = 148500;
-       struct dp_cr_status cr;
+       u8 link_status[DP_LINK_STATUS_SIZE];
        unsigned int training_step;
 
        if (!dp_ctrl)
@@ -1680,19 +1682,21 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
                }
 
                training_step = DP_TRAINING_NONE;
-               rc = dp_ctrl_setup_main_link(ctrl, &cr, &training_step);
+               rc = dp_ctrl_setup_main_link(ctrl, &training_step);
                if (rc == 0) {
                        /* training completed successfully */
                        break;
                } else if (training_step == DP_TRAINING_1) {
                        /* link train_1 failed */
-                       if (!dp_catalog_link_is_connected(ctrl->catalog)) {
+                       if (!dp_catalog_link_is_connected(ctrl->catalog))
                                break;
-                       }
+
+                       dp_ctrl_read_link_status(ctrl, link_status);
 
                        rc = dp_ctrl_link_rate_down_shift(ctrl);
                        if (rc < 0) { /* already in RBR = 1.6G */
-                               if (cr.lane_0_1 & DP_LANE0_1_CR_DONE) {
+                               if (dp_ctrl_clock_recovery_any_ok(link_status,
+                                       ctrl->link->link_params.num_lanes)) {
                                        /*
                                         * some lanes are ready,
                                         * reduce lane number
@@ -1708,12 +1712,18 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
                                }
                        }
                } else if (training_step == DP_TRAINING_2) {
-                       /* link train_2 failed, lower lane rate */
-                       if (!dp_catalog_link_is_connected(ctrl->catalog)) {
+                       /* link train_2 failed */
+                       if (!dp_catalog_link_is_connected(ctrl->catalog))
                                break;
-                       }
 
-                       rc = dp_ctrl_link_lane_down_shift(ctrl);
+                       dp_ctrl_read_link_status(ctrl, link_status);
+
+                       if (!drm_dp_clock_recovery_ok(link_status,
+                                       ctrl->link->link_params.num_lanes))
+                               rc = dp_ctrl_link_rate_down_shift(ctrl);
+                       else
+                               rc = dp_ctrl_link_lane_down_shift(ctrl);
+
                        if (rc < 0) {
                                /* end with failure */
                                break; /* lane == 1 already */