Re: [PATCH v4] drm/msm/dp: add logs across DP driver for ease of debugging

[maitreye@codeaurora.org]

Thank you Stephen.

On 2021-07-22 13:31, Stephen Boyd wrote:
> Quoting maitreye (2021-07-21 16:19:40)
>> From: Maitreyee Rao <maitreye@codeaurora.org>
>> 
>> Add trace points across the MSM DP driver to help debug
>> interop issues.
>> 
>> Changes in v4:
>>  - Changed goto statement and used if else-if
> 
> I think drm likes to see all the changelog here to see patch evolution.
> 
Yes, I will fix this
>> 
>> Signed-off-by: Maitreyee Rao <maitreye@codeaurora.org>
>> ---
>> diff --git a/drivers/gpu/drm/msm/dp/dp_link.c 
>> b/drivers/gpu/drm/msm/dp/dp_link.c
>> index be986da..8c98ab7 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_link.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_link.c
>> @@ -1036,43 +1036,28 @@ int dp_link_process_request(struct dp_link 
>> *dp_link)
>> 
>>         if (link->request.test_requested == DP_TEST_LINK_EDID_READ) {
>>                 dp_link->sink_request |= DP_TEST_LINK_EDID_READ;
>> -               return ret;
>>         }
>> -
>> -       ret = dp_link_process_ds_port_status_change(link);
>> -       if (!ret) {
>> +       else if (!(ret = dp_link_process_ds_port_status_change(link))) 
>> {
>>                 dp_link->sink_request |= DS_PORT_STATUS_CHANGED;
>> -               return ret;
>>         }
>> -
>> -       ret = dp_link_process_link_training_request(link);
>> -       if (!ret) {
>> +       else if (!(ret = dp_link_process_link_training_request(link))) 
>> {
>>                 dp_link->sink_request |= DP_TEST_LINK_TRAINING;
>> -               return ret;
>>         }
>> -
>> -       ret = dp_link_process_phy_test_pattern_request(link);
>> -       if (!ret) {
>> +       else if (!(ret = 
>> dp_link_process_phy_test_pattern_request(link))) {
>>                 dp_link->sink_request |= 
>> DP_TEST_LINK_PHY_TEST_PATTERN;
>> -               return ret;
>> -       }
>> -
>> -       ret = dp_link_process_link_status_update(link);
>> -       if (!ret) {
>> +       }
>> +       else if (!(ret = dp_link_process_link_status_update(link))) {
> 
> The kernel coding style is to leave the brackets on the same line
> 
> 	if (condition) {
> 
> 	} else if (conditon) {
> 
> 	}
> 
> See Documentation/process/coding-style.rst
> 
Yes, I will fix this

> Also, the if (!(ret = dp_link_...)) style is really hard to read. Maybe
> apply this patch before?
> 
> ----8<----
> diff --git a/drivers/gpu/drm/msm/dp/dp_link.c 
> b/drivers/gpu/drm/msm/dp/dp_link.c
> index 1195044a7a3b..408cddd90f0f 100644
> --- a/drivers/gpu/drm/msm/dp/dp_link.c
> +++ b/drivers/gpu/drm/msm/dp/dp_link.c
> @@ -1027,41 +1027,22 @@ int dp_link_process_request(struct dp_link 
> *dp_link)
> 
>  	if (link->request.test_requested == DP_TEST_LINK_EDID_READ) {
>  		dp_link->sink_request |= DP_TEST_LINK_EDID_READ;
> -		return ret;
> -	}
> -
> -	ret = dp_link_process_ds_port_status_change(link);
> -	if (!ret) {
> +	} else if (!dp_link_process_ds_port_status_change(link)) {
>  		dp_link->sink_request |= DS_PORT_STATUS_CHANGED;
> -		return ret;
> -	}
> -
> -	ret = dp_link_process_link_training_request(link);
> -	if (!ret) {
> +	} else if (!dp_link_process_link_training_request(link)) {
>  		dp_link->sink_request |= DP_TEST_LINK_TRAINING;
> -		return ret;
> -	}
> -
> -	ret = dp_link_process_phy_test_pattern_request(link);
> -	if (!ret) {
> +	} else if (!dp_link_process_phy_test_pattern_request(link)) {
>  		dp_link->sink_request |= DP_TEST_LINK_PHY_TEST_PATTERN;
> -		return ret;
> -	}
> -
> -	ret = dp_link_process_link_status_update(link);
> -	if (!ret) {
> +	} else if (!dp_link_process_link_status_update(link)) {
>  		dp_link->sink_request |= DP_LINK_STATUS_UPDATED;
> -		return ret;
> -	}
> -
> -	if (dp_link_is_video_pattern_requested(link)) {
> -		ret = 0;
> -		dp_link->sink_request |= DP_TEST_LINK_VIDEO_PATTERN;
> -	}
> +	} else {
> +		if (dp_link_is_video_pattern_requested(link))
> +			dp_link->sink_request |= DP_TEST_LINK_VIDEO_PATTERN;
> 
> -	if (dp_link_is_audio_pattern_requested(link)) {
> -		dp_link->sink_request |= DP_TEST_LINK_AUDIO_PATTERN;
> -		return -EINVAL;
> +		if (dp_link_is_audio_pattern_requested(link)) {
> +			dp_link->sink_request |= DP_TEST_LINK_AUDIO_PATTERN;
> +			ret = -EINVAL;
> +		}
>  	}
> 
>  	return ret;
The reason I did this was to preserve the value of ret as the caller of 
the function checks it. Some functions return -EINVAl like in here:
https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/msm/dp/dp_link.c#L972 
, so to check that it would be necessary to get the ret value.