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    Subject[PATCH 5.15 002/107] drm/msm/dp: delete DP_RECOVERED_CLOCK_OUT_EN to fix tps4
    Date
    From: Kuogee Hsieh <quic_khsieh@quicinc.com>

    [ Upstream commit 032d57960176ac01cc5adff5bcc5eb51317f8781 ]

    Data Symbols scrambled is required for tps4 at link training 2.
    Therefore SCRAMBLING_DISABLE bit should not be set for tps4 to
    work.

    RECOVERED_CLOCK_OUT_EN is for enable simple EYE test for jitter
    measurement with minimal equipment for embedded applications purpose
    and is not required to be set during normal operation. Current
    implementation always have RECOVERED_CLOCK_OUT_EN bit set which
    cause SCRAMBLING_DISABLE bit wrongly set at tps4 which prevent
    tps4 from working.

    This patch delete setting RECOVERED_CLOCK_OUT_EN to fix
    SCRAMBLING_DISABLE be wrongly set at tps4.

    Changes in v2:
    -- fix Fixes tag

    Changes in v3:
    -- revise commit text

    Changes in v4:
    -- fix commit text newline

    Changes in v5:
    -- fix commit text line over 75 chars

    Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
    Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>

    Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
    Reviewed-by: Stephen Boyd <swboyd@chromium.org>
    Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
    Patchwork: https://patchwork.freedesktop.org/patch/497194/
    Link: https://lore.kernel.org/r/1660258670-4200-1-git-send-email-quic_khsieh@quicinc.com
    Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/gpu/drm/msm/dp/dp_ctrl.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
    index b6f4ce2a48afe..6d9eec98e0d38 100644
    --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
    +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
    @@ -1198,7 +1198,7 @@ static int dp_ctrl_link_train_2(struct dp_ctrl_private *ctrl,
    if (ret)
    return ret;

    - dp_ctrl_train_pattern_set(ctrl, pattern | DP_RECOVERED_CLOCK_OUT_EN);
    + dp_ctrl_train_pattern_set(ctrl, pattern);

    for (tries = 0; tries <= maximum_retries; tries++) {
    drm_dp_link_train_channel_eq_delay(ctrl->aux, ctrl->panel->dpcd);
    --
    2.35.1


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