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From: Stephen Boyd <swboyd@chromium.org>
To: maitreye@codeaurora.org
Cc: dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
	abhinavk@codeaurora.org, khsieh@codeaurora.org,
	seanpaul@chromium.org, aravindh@codeaurora.org,
	freedreno@lists.freedesktop.org
Subject: Re: [PATCH v4] drm/msm/dp: add logs across DP driver for ease of debugging
Date: Thu, 22 Jul 2021 22:09:09 +0000	[thread overview]
Message-ID: <CAE-0n522OEz8YwKRb8VZtSbwAdjXReEPCwvL8N7kWycGSrbvxw@mail.gmail.com> (raw)
In-Reply-To: <4a97d331d7a60cb4756899d98f81ca4f@codeaurora.org>

Quoting maitreye@codeaurora.org (2021-07-22 14:33:43)
> 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.

ret is overwritten multiple times. The logic seems to be if ret is
not-zero, reassign it, until we get to the end. How about this

----8<----
diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
index 1195044a7a3b..e59138566c0a 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -1027,41 +1027,27 @@ 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) {
-		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;
-	}
-
-	if (dp_link_is_audio_pattern_requested(link)) {
-		dp_link->sink_request |= DP_TEST_LINK_AUDIO_PATTERN;
-		return -EINVAL;
+	} else {
+		ret = dp_link_process_link_status_update(link);
+		if (!ret) {
+			dp_link->sink_request |= DP_LINK_STATUS_UPDATED;
+		} else {
+			if (dp_link_is_video_pattern_requested(link)) {
+				ret = 0;
+				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;
+				ret = -EINVAL;
+			}
+		}
 	}

 	return ret;

  reply	other threads:[~2021-07-22 22:09 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-21 23:19 [PATCH v4] drm/msm/dp: add logs across DP driver for ease of debugging maitreye
2021-07-22 20:31 ` Stephen Boyd
2021-07-22 21:33   ` maitreye
2021-07-22 22:09     ` Stephen Boyd [this message]
2021-07-23  3:53       ` maitreye
2021-07-23 19:32         ` Stephen Boyd

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