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

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