diff mbox series

[2/7] drm/msm/dp: reduce link rate if failed at link training 1

Message ID 1625592020-22658-3-git-send-email-khsieh@codeaurora.org (mailing list archive)
State New, archived
Headers show
Series add fixes to pass DP Link Layer compliance test cases | expand

Commit Message

Kuogee Hsieh July 6, 2021, 5:20 p.m. UTC
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.

Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c | 86 ++++++++++++++++++++++++++--------------
 1 file changed, 56 insertions(+), 30 deletions(-)

Comments

Stephen Boyd July 8, 2021, 7:33 a.m. UTC | #1
Quoting Kuogee Hsieh (2021-07-06 10:20:15)
> 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.
>
> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
> ---
>  drivers/gpu/drm/msm/dp/dp_ctrl.c | 86 ++++++++++++++++++++++++++--------------
>  1 file changed, 56 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 27fb0f0..6f8443d 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -83,13 +83,6 @@ 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)
> +               u8 *cr, int *training_step)
>  {
>         int tries, old_v_level, ret = 0;
>         u8 link_status[DP_LINK_STATUS_SIZE];
> @@ -1109,8 +1102,8 @@ 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];
> +               cr[0] = link_status[0];
> +               cr[1] = link_status[1];
>
>                 if (drm_dp_clock_recovery_ok(link_status,
>                         ctrl->link->link_params.num_lanes)) {
> @@ -1188,7 +1181,7 @@ 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)
> +               u8 *cr, int *training_step)
>  {
>         int tries = 0, ret = 0;
>         char pattern;
> @@ -1204,10 +1197,6 @@ 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 +1209,8 @@ 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];
> +               cr[0] = link_status[0];
> +               cr[1] = link_status[1];
>
>                 if (drm_dp_channel_eq_ok(link_status,
>                         ctrl->link->link_params.num_lanes)) {
> @@ -1241,7 +1230,7 @@ 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)
> +               u8 *cr, int *training_step)
>  {
>         int ret = 0;
>         u8 encoding = DP_SET_ANSI_8B10B;
> @@ -1282,7 +1271,7 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
>  }
>
>  static int dp_ctrl_setup_main_link(struct dp_ctrl_private *ctrl,
> -               struct dp_cr_status *cr, int *training_step)
> +               u8 *cr, int *training_step)
>  {
>         int ret = 0;
>
> @@ -1496,14 +1485,14 @@ 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;
> +       u8 cr_status[2];
>         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, cr_status, &training_step);
>         if (ret)
>                 goto end;

Do we need to extract the link status information from deep in these
functions? Why not read it again when we need to?

>
> @@ -1634,6 +1623,41 @@ void dp_ctrl_handle_sink_request(struct dp_ctrl *dp_ctrl)
>         }
>  }
>
> +static bool dp_ctrl_any_lane_cr_done(struct dp_ctrl_private *ctrl,
> +                                       u8 *cr_status)
> +
> +{
> +       int i;
> +       u8 status;
> +       int lane = ctrl->link->link_params.num_lanes;
> +
> +       for (i = 0; i < lane; i++) {
> +               status = cr_status[i / 2];
> +               status >>= ((i % 2) * 4);
> +               if (status & DP_LANE_CR_DONE)
> +                       return true;
> +       }
> +
> +       return false;
> +}
> +
> +static bool dp_ctrl_any_lane_cr_lose(struct dp_ctrl_private *ctrl,
> +                                       u8 *cr_status)
> +{
> +       int i;
> +       u8 status;
> +       int lane = ctrl->link->link_params.num_lanes;
> +
> +       for (i = 0; i < lane; i++) {
> +               status = cr_status[i / 2];
> +               status >>= ((i % 2) * 4);
> +               if (!(status & DP_LANE_CR_DONE))
> +                       return true;
> +       }
> +
> +       return false;
> +}

Why not use !drm_dp_clock_recovery_ok() for dp_ctrl_any_lane_cr_lose()?
And then move dp_ctrl_any_lane_cr_done() next to
drm_dp_clock_recovery_ok() and call it drm_dp_clock_recovery_any_ok()?

> +
>  int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
>  {
>         int rc = 0;
> @@ -1641,7 +1665,7 @@ 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 cr_status[2];
>         unsigned int training_step;
>
>         if (!dp_ctrl)
> @@ -1681,19 +1705,18 @@ 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, cr_status, &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;
> -                       }
>
>                         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_any_lane_cr_done(ctrl, cr_status)) {
>                                         /*
>                                          * some lanes are ready,
>                                          * reduce lane number
> @@ -1709,12 +1732,15 @@ 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);
> +                       if (dp_ctrl_any_lane_cr_lose(ctrl, cr_status))
> +                               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 */
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
Kuogee Hsieh July 9, 2021, 5:46 p.m. UTC | #2
On 2021-07-08 00:33, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2021-07-06 10:20:15)
>> 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.
>> 
>> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
>> ---
>>  drivers/gpu/drm/msm/dp/dp_ctrl.c | 86 
>> ++++++++++++++++++++++++++--------------
>>  1 file changed, 56 insertions(+), 30 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c 
>> b/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> index 27fb0f0..6f8443d 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> @@ -83,13 +83,6 @@ 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)
>> +               u8 *cr, int *training_step)
>>  {
>>         int tries, old_v_level, ret = 0;
>>         u8 link_status[DP_LINK_STATUS_SIZE];
>> @@ -1109,8 +1102,8 @@ 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];
>> +               cr[0] = link_status[0];
>> +               cr[1] = link_status[1];
>> 
>>                 if (drm_dp_clock_recovery_ok(link_status,
>>                         ctrl->link->link_params.num_lanes)) {
>> @@ -1188,7 +1181,7 @@ 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)
>> +               u8 *cr, int *training_step)
>>  {
>>         int tries = 0, ret = 0;
>>         char pattern;
>> @@ -1204,10 +1197,6 @@ 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 +1209,8 @@ 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];
>> +               cr[0] = link_status[0];
>> +               cr[1] = link_status[1];
>> 
>>                 if (drm_dp_channel_eq_ok(link_status,
>>                         ctrl->link->link_params.num_lanes)) {
>> @@ -1241,7 +1230,7 @@ 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)
>> +               u8 *cr, int *training_step)
>>  {
>>         int ret = 0;
>>         u8 encoding = DP_SET_ANSI_8B10B;
>> @@ -1282,7 +1271,7 @@ static int dp_ctrl_link_train(struct 
>> dp_ctrl_private *ctrl,
>>  }
>> 
>>  static int dp_ctrl_setup_main_link(struct dp_ctrl_private *ctrl,
>> -               struct dp_cr_status *cr, int *training_step)
>> +               u8 *cr, int *training_step)
>>  {
>>         int ret = 0;
>> 
>> @@ -1496,14 +1485,14 @@ 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;
>> +       u8 cr_status[2];
>>         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, cr_status, 
>> &training_step);
>>         if (ret)
>>                 goto end;
> 
> Do we need to extract the link status information from deep in these
> functions? Why not read it again when we need to?
> 
>> 
>> @@ -1634,6 +1623,41 @@ void dp_ctrl_handle_sink_request(struct dp_ctrl 
>> *dp_ctrl)
>>         }
>>  }
>> 
>> +static bool dp_ctrl_any_lane_cr_done(struct dp_ctrl_private *ctrl,
>> +                                       u8 *cr_status)
>> +
>> +{
>> +       int i;
>> +       u8 status;
>> +       int lane = ctrl->link->link_params.num_lanes;
>> +
>> +       for (i = 0; i < lane; i++) {
>> +               status = cr_status[i / 2];
>> +               status >>= ((i % 2) * 4);
>> +               if (status & DP_LANE_CR_DONE)
>> +                       return true;
>> +       }
>> +
>> +       return false;
>> +}
>> +
>> +static bool dp_ctrl_any_lane_cr_lose(struct dp_ctrl_private *ctrl,
>> +                                       u8 *cr_status)
>> +{
>> +       int i;
>> +       u8 status;
>> +       int lane = ctrl->link->link_params.num_lanes;
>> +
>> +       for (i = 0; i < lane; i++) {
>> +               status = cr_status[i / 2];
>> +               status >>= ((i % 2) * 4);
>> +               if (!(status & DP_LANE_CR_DONE))
>> +                       return true;
>> +       }
>> +
>> +       return false;
>> +}
> 
> Why not use !drm_dp_clock_recovery_ok() for dp_ctrl_any_lane_cr_lose()?
ok,

> And then move dp_ctrl_any_lane_cr_done() next to
> drm_dp_clock_recovery_ok() and call it drm_dp_clock_recovery_any_ok()?
no understand how it work, can you elaborate it more?
> 
>> +
>>  int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
>>  {
>>         int rc = 0;
>> @@ -1641,7 +1665,7 @@ 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 cr_status[2];
>>         unsigned int training_step;
>> 
>>         if (!dp_ctrl)
>> @@ -1681,19 +1705,18 @@ 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, cr_status, 
>> &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;
>> -                       }
>> 
>>                         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_any_lane_cr_done(ctrl, 
>> cr_status)) {
>>                                         /*
>>                                          * some lanes are ready,
>>                                          * reduce lane number
>> @@ -1709,12 +1732,15 @@ 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);
>> +                       if (dp_ctrl_any_lane_cr_lose(ctrl, cr_status))
>> +                               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 */
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>>
Stephen Boyd July 15, 2021, 6:59 p.m. UTC | #3
Quoting khsieh@codeaurora.org (2021-07-09 10:46:41)
> On 2021-07-08 00:33, Stephen Boyd wrote:
> >> +
> >> +static bool dp_ctrl_any_lane_cr_lose(struct dp_ctrl_private *ctrl,
> >> +                                       u8 *cr_status)
> >> +{
> >> +       int i;
> >> +       u8 status;
> >> +       int lane = ctrl->link->link_params.num_lanes;
> >> +
> >> +       for (i = 0; i < lane; i++) {
> >> +               status = cr_status[i / 2];
> >> +               status >>= ((i % 2) * 4);
> >> +               if (!(status & DP_LANE_CR_DONE))
> >> +                       return true;
> >> +       }
> >> +
> >> +       return false;
> >> +}
> >
> > Why not use !drm_dp_clock_recovery_ok() for dp_ctrl_any_lane_cr_lose()?
> ok,
>
> > And then move dp_ctrl_any_lane_cr_done() next to
> > drm_dp_clock_recovery_ok() and call it drm_dp_clock_recovery_any_ok()?
> no understand how it work, can you elaborate it more?

I'm suggesting to make a new function called
drm_dp_clock_recovery_any_ok(), written next to
drm_dp_clock_recovery_ok(). Then call it from here instead of implement
it locally in the qcom DP driver.
diff mbox series

Patch

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index 27fb0f0..6f8443d 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -83,13 +83,6 @@  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)
+		u8 *cr, int *training_step)
 {
 	int tries, old_v_level, ret = 0;
 	u8 link_status[DP_LINK_STATUS_SIZE];
@@ -1109,8 +1102,8 @@  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];
+		cr[0] = link_status[0];
+		cr[1] = link_status[1];
 
 		if (drm_dp_clock_recovery_ok(link_status,
 			ctrl->link->link_params.num_lanes)) {
@@ -1188,7 +1181,7 @@  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)
+		u8 *cr, int *training_step)
 {
 	int tries = 0, ret = 0;
 	char pattern;
@@ -1204,10 +1197,6 @@  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 +1209,8 @@  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];
+		cr[0] = link_status[0];
+		cr[1] = link_status[1];
 
 		if (drm_dp_channel_eq_ok(link_status,
 			ctrl->link->link_params.num_lanes)) {
@@ -1241,7 +1230,7 @@  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)
+		u8 *cr, int *training_step)
 {
 	int ret = 0;
 	u8 encoding = DP_SET_ANSI_8B10B;
@@ -1282,7 +1271,7 @@  static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
 }
 
 static int dp_ctrl_setup_main_link(struct dp_ctrl_private *ctrl,
-		struct dp_cr_status *cr, int *training_step)
+		u8 *cr, int *training_step)
 {
 	int ret = 0;
 
@@ -1496,14 +1485,14 @@  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;
+	u8 cr_status[2];
 	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, cr_status, &training_step);
 	if (ret)
 		goto end;
 
@@ -1634,6 +1623,41 @@  void dp_ctrl_handle_sink_request(struct dp_ctrl *dp_ctrl)
 	}
 }
 
+static bool dp_ctrl_any_lane_cr_done(struct dp_ctrl_private *ctrl,
+					u8 *cr_status)
+
+{
+	int i;
+	u8 status;
+	int lane = ctrl->link->link_params.num_lanes;
+
+	for (i = 0; i < lane; i++) {
+		status = cr_status[i / 2];
+		status >>= ((i % 2) * 4);
+		if (status & DP_LANE_CR_DONE)
+			return true;
+	}
+
+	return false;
+}
+
+static bool dp_ctrl_any_lane_cr_lose(struct dp_ctrl_private *ctrl,
+					u8 *cr_status)
+{
+	int i;
+	u8 status;
+	int lane = ctrl->link->link_params.num_lanes;
+
+	for (i = 0; i < lane; i++) {
+		status = cr_status[i / 2];
+		status >>= ((i % 2) * 4);
+		if (!(status & DP_LANE_CR_DONE))
+			return true;
+	}
+
+	return false;
+}
+
 int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
 {
 	int rc = 0;
@@ -1641,7 +1665,7 @@  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 cr_status[2];
 	unsigned int training_step;
 
 	if (!dp_ctrl)
@@ -1681,19 +1705,18 @@  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, cr_status, &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;
-			}
 
 			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_any_lane_cr_done(ctrl, cr_status)) {
 					/*
 					 * some lanes are ready,
 					 * reduce lane number
@@ -1709,12 +1732,15 @@  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);
+			if (dp_ctrl_any_lane_cr_lose(ctrl, cr_status))
+				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 */