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SubjectRe: [PATCH] drm/msm/dp: add support of tps4 (training pattern 4) for HBR3
On Tue 28 Dec 10:51 PST 2021, Kuogee Hsieh wrote:

> From: Kuogee Hsieh <khsieh@codeaurora.org>
>
> Some DP sinkers prefer to use tps4 instead of tps3 during training #2.
> This patch will use tps4 to perform link training #2 if sinker's DPCD
> supports it.
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> ---
> drivers/gpu/drm/msm/dp/dp_ctrl.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 39558a2..c7b0657 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -1181,7 +1181,7 @@ static int dp_ctrl_link_train_2(struct dp_ctrl_private *ctrl,
> int *training_step)
> {
> int tries = 0, ret = 0;
> - char pattern;
> + char pattern, state_ctrl_bit;
> int const maximum_retries = 5;
> u8 link_status[DP_LINK_STATUS_SIZE];
>
> @@ -1189,12 +1189,20 @@ static int dp_ctrl_link_train_2(struct dp_ctrl_private *ctrl,
>
> *training_step = DP_TRAINING_2;
>
> - if (drm_dp_tps3_supported(ctrl->panel->dpcd))
> + if (drm_dp_tps4_supported(ctrl->panel->dpcd)) {
> + pattern = DP_TRAINING_PATTERN_4;
> + state_ctrl_bit = 4;
> + }
> + else if (drm_dp_tps3_supported(ctrl->panel->dpcd)) {
> pattern = DP_TRAINING_PATTERN_3;
> - else
> + state_ctrl_bit = 3;
> + }
> + else {
> pattern = DP_TRAINING_PATTERN_2;
> + state_ctrl_bit = 2;
> + }
>
> - ret = dp_catalog_ctrl_set_pattern(ctrl->catalog, pattern);
> + ret = dp_catalog_ctrl_set_pattern(ctrl->catalog, state_ctrl_bit);

The patch looks good, but as the state_ctrl_bit is no longer equal to
DP_PATTERN_n the function and argument names are misleading.

Please rename it to something like
"dp_catalog_ctrl_set_pattern_state_bit()" and the "pattern" argument
within that function to "state_bit".

Thanks,
Bjorn

> if (ret)
> return ret;
>
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

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