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

[maitreye@xxxxxxxxxxxxxx]

Thank you Stephen.

On 2021-07-22 13:31, Stephen Boyd wrote:
> Quoting maitreye (2021-07-21 16:19:40)
> > From: Maitreyee Rao <maitreye@xxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxx>
> > ---
> > 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.