linux-kernel - Re: [RFT PATCH 13/15] drm/imx/ipuv3: Call drm_atomic_helper

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Message-ID: <CAD=FV=WLw3cAU0nuNuKXiu=Zbv4tVa3aa35GFaxsjO880T0pmw@mail.gmail.com>
Date:   Tue, 5 Sep 2023 13:29:00 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Philipp Zabel <p.zabel@...gutronix.de>
Cc:     dri-devel@...ts.freedesktop.org,
        Maxime Ripard <mripard@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>, airlied@...il.com,
        daniel@...ll.ch, festevam@...il.com, kernel@...gutronix.de,
        linux-arm-kernel@...ts.infradead.org, linux-imx@....com,
        linux-kernel@...r.kernel.org, shawnguo@...nel.org
Subject: Re: [RFT PATCH 13/15] drm/imx/ipuv3: Call drm_atomic_helper_shutdown()
 at shutdown/unbind time

Hi,

On Mon, Sep 4, 2023 at 1:30 AM Philipp Zabel <p.zabel@...gutronix.de> wrote:
>
> On Fr, 2023-09-01 at 16:41 -0700, Douglas Anderson wrote:
> > Based on grepping through the source code this driver appears to be
> > missing a call to drm_atomic_helper_shutdown() at system shutdown time
> > and at driver unbind time. Among other things, this means that if a
> > panel is in use that it won't be cleanly powered off at system
> > shutdown time.
> >
> > The fact that we should call drm_atomic_helper_shutdown() in the case
> > of OS shutdown/restart and at driver remove (or unbind) time comes
> > straight out of the kernel doc "driver instance overview" in
> > drm_drv.c.
> >
> > A few notes about this fix:
> > - When adding drm_atomic_helper_shutdown() to the unbind path, I added
> >   it after drm_kms_helper_poll_fini() since that's when other drivers
> >   seemed to have it.
> > - Technically with a previous patch, ("drm/atomic-helper:
> >   drm_atomic_helper_shutdown(NULL) should be a noop"), we don't
> >   actually need to check to see if our "drm" pointer is NULL before
> >   calling drm_atomic_helper_shutdown(). We'll leave the "if" test in,
> >   though, so that this patch can land without any dependencies. It
> >   could potentially be removed later.
> > - This patch also makes sure to set the drvdata to NULL in the case of
> >   bind errors to make sure that shutdown can't access freed data.
> >
> > Suggested-by: Maxime Ripard <mripard@...nel.org>
> > Signed-off-by: Douglas Anderson <dianders@...omium.org>
>
> Thank you,
> Tested-by: Philipp Zabel <p.zabel@...gutronix.de>

Thanks! I notice that:

./scripts/get_maintainer.pl --scm -f drivers/gpu/drm/imx/ipuv3/imx-drm-core.c

Doesn't say drm-misc but also when I look at the MAINTAINERS file and
find the section for "DRM DRIVERS FOR FREESCALE IMX" it doesn't
explicitly list a different git tree. I guess the "shawnguo" git tree
listed by get_maintainer.pl is just from regex matching?

Would you expect this to go through drm-misc? If so, I'll probably
land it sooner rather than later. I can also post up a patch making it
obvious that "DRM DRIVERS FOR FREESCALE IMX" goes through drm-misc if
you don't object.

Thanks!

-Doug