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    Subject[PATCH AUTOSEL 5.14 142/252] drm/msm/dp: reduce link rate if failed at link training 1
    Date
    From: Kuogee Hsieh <khsieh@codeaurora.org>

    [ Upstream commit 4b85d405cfe938ae7ad61656484ae88dee289e3b ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/gpu/drm/msm/dp/dp_ctrl.c | 78 ++++++++++++++++++--------------
    1 file changed, 44 insertions(+), 34 deletions(-)

    diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
    index eaddfd739885..30d20e3beb29 100644
    --- 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)
    {
    @@ -1078,7 +1071,7 @@ 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];
    @@ -1107,9 +1100,6 @@ 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;
    @@ -1186,7 +1176,7 @@ 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;
    @@ -1202,10 +1192,6 @@ 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;
    @@ -1218,8 +1204,6 @@ 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)) {
    @@ -1239,7 +1223,7 @@ 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;
    @@ -1255,7 +1239,7 @@ 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;
    @@ -1264,7 +1248,7 @@ 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;
    @@ -1280,7 +1264,7 @@ 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)
    + int *training_step)
    {
    int ret = 0;

    @@ -1295,7 +1279,7 @@ 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;
    }
    @@ -1492,14 +1476,13 @@ 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;

    @@ -1630,6 +1613,25 @@ 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;
    @@ -1637,7 +1639,7 @@ 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)
    @@ -1677,19 +1679,21 @@ 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
    @@ -1705,12 +1709,18 @@ 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 */
    --
    2.30.2
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      Last update: 2021-09-09 13:55    [W:4.152 / U:0.220 seconds]
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