2021-12-17 00:19:16

by Bjorn Andersson

Subject: [PATCH v2] drm/msm/dp: Only create debugfs for PRIMARY minor

dpu_kms_debugfs_init() is invoked for each minor being registered. Most
of the files created are unrelated to the minor, so there's no reason to
present them per minor.
The exception to this is the DisplayPort code, which ends up invoking
dp_debug_get() for each minor, each time associate the allocated object
with dp->debug.

As such dp_debug will create debugfs files in both the PRIMARY and the
RENDER minor's debugfs directory, but only the last reference will be
remembered.

The only use of this reference today is in the cleanup path in
dp_display_deinit_sub_modules() and the dp_debug_private object does
outlive the debugfs entries in either case, so there doesn't seem to be
any adverse effects of this, but per the code the current behavior is
unexpected, so change it to only create debugfs files for the PRIMARY
minor.

Signed-off-by: Bjorn Andersson <[email protected]>
---

Changes since v1:
- Moved the check up from msm_dp_debugfs_init() to dpu_kms_debugfs_init()

drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index 2ee70072a1b4..a54f7d373f14 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -193,6 +193,10 @@ static int dpu_kms_debugfs_init(struct msm_kms *kms, struct drm_minor *minor)
if (!p)
return -EINVAL;

+ /* Only create one set of debugfs per DP instance */
+ if (minor->type != DRM_MINOR_PRIMARY)
+ return 0;
+
dev = dpu_kms->dev;
priv = dev->dev_private;

--
2.33.1

2021-12-20 19:51:42

by Abhinav Kumar

Subject: Re: [PATCH v2] drm/msm/dp: Only create debugfs for PRIMARY minor

On 12/16/2021 4:20 PM, Bjorn Andersson wrote:
> dpu_kms_debugfs_init() is invoked for each minor being registered. Most
> of the files created are unrelated to the minor, so there's no reason to
> present them per minor.
> The exception to this is the DisplayPort code, which ends up invoking
> dp_debug_get() for each minor, each time associate the allocated object
> with dp->debug.
>
> As such dp_debug will create debugfs files in both the PRIMARY and the
> RENDER minor's debugfs directory, but only the last reference will be
> remembered.
>
> The only use of this reference today is in the cleanup path in
> dp_display_deinit_sub_modules() and the dp_debug_private object does
> outlive the debugfs entries in either case, so there doesn't seem to be
> any adverse effects of this, but per the code the current behavior is
> unexpected, so change it to only create debugfs files for the PRIMARY
> minor.
>
> Signed-off-by: Bjorn Andersson <[email protected]>
> ---
>
> Changes since v1:
> - Moved the check up from msm_dp_debugfs_init() to dpu_kms_debugfs_init()
>
> drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index 2ee70072a1b4..a54f7d373f14 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -193,6 +193,10 @@ static int dpu_kms_debugfs_init(struct msm_kms *kms, struct drm_minor *minor)
> if (!p)
> return -EINVAL;
>
> + /* Only create one set of debugfs per DP instance */
I would change this to DPU now instead of DP, but apart from that,

Reviewed-by: Abhinav Kumar <[email protected]>
> + if (minor->type != DRM_MINOR_PRIMARY)
> + return 0;
> +
> dev = dpu_kms->dev;
> priv = dev->dev_private;
>

2021-12-20 23:53:30

by Dmitry Baryshkov

Subject: Re: [PATCH v2] drm/msm/dp: Only create debugfs for PRIMARY minor

On Fri, 17 Dec 2021 at 03:19, Bjorn Andersson
<[email protected]> wrote:
>
> dpu_kms_debugfs_init() is invoked for each minor being registered. Most
> of the files created are unrelated to the minor, so there's no reason to
> present them per minor.
> The exception to this is the DisplayPort code, which ends up invoking
> dp_debug_get() for each minor, each time associate the allocated object
> with dp->debug.
>
> As such dp_debug will create debugfs files in both the PRIMARY and the
> RENDER minor's debugfs directory, but only the last reference will be
> remembered.
>
> The only use of this reference today is in the cleanup path in
> dp_display_deinit_sub_modules() and the dp_debug_private object does
> outlive the debugfs entries in either case, so there doesn't seem to be
> any adverse effects of this, but per the code the current behavior is
> unexpected, so change it to only create debugfs files for the PRIMARY
> minor.
>
> Signed-off-by: Bjorn Andersson <[email protected]>
> ---
>
> Changes since v1:
> - Moved the check up from msm_dp_debugfs_init() to dpu_kms_debugfs_init()
>
> drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index 2ee70072a1b4..a54f7d373f14 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -193,6 +193,10 @@ static int dpu_kms_debugfs_init(struct msm_kms *kms, struct drm_minor *minor)
> if (!p)
> return -EINVAL;
>
> + /* Only create one set of debugfs per DP instance */

The comment is misleading. Could you please fix it?

> + if (minor->type != DRM_MINOR_PRIMARY)
> + return 0;
> +
> dev = dpu_kms->dev;
> priv = dev->dev_private;
>
> --
> 2.33.1
>


--
With best wishes
Dmitry

2021-12-21 00:01:26

by Bjorn Andersson

Subject: Re: [PATCH v2] drm/msm/dp: Only create debugfs for PRIMARY minor

On Mon 20 Dec 15:53 PST 2021, Dmitry Baryshkov wrote:

> On Fri, 17 Dec 2021 at 03:19, Bjorn Andersson
> <[email protected]> wrote:
> >
> > dpu_kms_debugfs_init() is invoked for each minor being registered. Most
> > of the files created are unrelated to the minor, so there's no reason to
> > present them per minor.
> > The exception to this is the DisplayPort code, which ends up invoking
> > dp_debug_get() for each minor, each time associate the allocated object
> > with dp->debug.
> >
> > As such dp_debug will create debugfs files in both the PRIMARY and the
> > RENDER minor's debugfs directory, but only the last reference will be
> > remembered.
> >
> > The only use of this reference today is in the cleanup path in
> > dp_display_deinit_sub_modules() and the dp_debug_private object does
> > outlive the debugfs entries in either case, so there doesn't seem to be
> > any adverse effects of this, but per the code the current behavior is
> > unexpected, so change it to only create debugfs files for the PRIMARY
> > minor.
> >
> > Signed-off-by: Bjorn Andersson <[email protected]>
> > ---
> >
> > Changes since v1:
> > - Moved the check up from msm_dp_debugfs_init() to dpu_kms_debugfs_init()
> >
> > drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > index 2ee70072a1b4..a54f7d373f14 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > @@ -193,6 +193,10 @@ static int dpu_kms_debugfs_init(struct msm_kms *kms, struct drm_minor *minor)
> > if (!p)
> > return -EINVAL;
> >
> > + /* Only create one set of debugfs per DP instance */
>
> The comment is misleading. Could you please fix it?
>

I agree, and as Abhinav pointed out I didn't update $subject fully
either.

Will resubmit.

Regards,
Bjorn

> > + if (minor->type != DRM_MINOR_PRIMARY)
> > + return 0;
> > +
> > dev = dpu_kms->dev;
> > priv = dev->dev_private;
> >
> > --
> > 2.33.1
> >
>
>
> --
> With best wishes
> Dmitry