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
Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
Signed-off-by: Kuogee Hsieh <[email protected]>
---
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 ab6aa13..013ca02 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1214,7 +1214,7 @@ 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);
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
On 8/1/2022 1:13 PM, Kuogee Hsieh wrote:
> 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
>
> Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
> Signed-off-by: Kuogee Hsieh <[email protected]>
This is a good catch !
Reviewed-by: Abhinav Kumar <[email protected]>
> ---
> 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 ab6aa13..013ca02 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -1214,7 +1214,7 @@ 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);
Quoting Kuogee Hsieh (2022-08-01 13:13:50)
> 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
>
> Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
> Signed-off-by: Kuogee Hsieh <[email protected]>
> ---
Reviewed-by: Stephen Boyd <[email protected]>
On 01/08/2022 23:13, Kuogee Hsieh wrote:
> 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.
Minor nits, more likely concerning feature patches:
- Please insert blank lines between paragraphs, it makes commit message
easier to read. And please add no extra line breaks if you do not intent
to end the paragraph here.
- "This patch" is generally the frowned upon phrase (see
Documentation/process/submitting-patches.rst)
Nevertheless:
Reviewed-by: Dmitry Baryshkov <[email protected]>
>
> Changes in v2:
> -- fix Fixes tag
>
> Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
> Signed-off-by: Kuogee Hsieh <[email protected]>
> ---
> 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 ab6aa13..013ca02 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -1214,7 +1214,7 @@ 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);
--
With best wishes
Dmitry