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    Subject[PATCH] drm/bridge: Fixed a DP link training bug
    Date
    To have better compatibility for DP sink, there is a retry mechanism
    for the link training process to switch between different training process.
    The original driver code doesn't reset the retry counter when training
    state is pass. If the system triggers link training over 3 times,
    there will be a chance to causes the driver to use the wrong training
    method and return a training fail result.

    To Fix this, we reset the retry counter when training state is pass
    each time.

    Signed-off-by: Allen Chen <allen.chen@ite.corp-partner.google.com>
    Signed-off-by: xiazhengqiao <xiazhengqiao@huaqin.corp-partner.google.com>
    ---
    drivers/gpu/drm/bridge/ite-it6505.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
    index 2f300f5ca051..b589136ca6da 100644
    --- a/drivers/gpu/drm/bridge/ite-it6505.c
    +++ b/drivers/gpu/drm/bridge/ite-it6505.c
    @@ -2240,11 +2240,13 @@ static void it6505_link_training_work(struct work_struct *work)
    ret = it6505_link_start_auto_train(it6505);
    DRM_DEV_DEBUG_DRIVER(dev, "auto train %s, auto_train_retry: %d",
    ret ? "pass" : "failed", it6505->auto_train_retry);
    - it6505->auto_train_retry--;

    if (ret) {
    + it6505->auto_train_retry = AUTO_TRAIN_RETRY;
    it6505_link_train_ok(it6505);
    return;
    + } else {
    + it6505->auto_train_retry--;
    }

    it6505_dump(it6505);
    --
    2.17.1

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