[PATCH resend v2] drm: renesas: shmobile: Call drm_helper_force_disable_all() at shutdown time

[Geert Uytterhoeven]

Hi Doug,

On Tue, Jun 11, 2024 at 7:33 PM Doug Anderson <dianders at chromium.org> wrote:
> On Wed, May 29, 2024 at 5:16 AM Geert Uytterhoeven
> <geert+renesas at glider.be> wrote:
> >
> > From: Douglas Anderson <dianders at chromium.org>
> >
> > Based on grepping through the source code, this driver appears to be
> > missing a call to drm_atomic_helper_shutdown() at system shutdown time.
> > This is important because drm_helper_force_disable_all() will cause
> > panels to get disabled cleanly which may be important for their power
> > sequencing.  Future changes will remove any custom powering off in
> > individual panel drivers so the DRM drivers need to start getting this
> > right.
> >
> > The fact that we should call drm_atomic_helper_shutdown() in the case of
> > OS shutdown comes straight out of the kernel doc "driver instance
> > overview" in drm_drv.c.
> >
> > Suggested-by: Maxime Ripard <mripard at kernel.org>
> > Signed-off-by: Douglas Anderson <dianders at chromium.org>
> > Link: https://lore.kernel.org/r/20230901164111.RFT.15.Iaf638a1d4c8b3c307a6192efabb4cbb06b195f15@changeid
> > [geert: s/drm_helper_force_disable_all/drm_atomic_helper_shutdown/]
> > [geert: shmob_drm_remove() already calls drm_atomic_helper_shutdown]
> > Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
> > Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> > v2:
> >   - Add Reviewed-by.
> >
> > Tested on Atmark Techno Armadillo-800-EVA.
> > ---
> >  drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
>
> FWIW: I've created a patch to list DRM modeset drivers that handle
> shutdown properly [1]. For now "shmob-drm" is not part of that
> patchset. Assuming my patch lands we'll have to later add it to the
> list.

Ouch, keeping such a list is ugly ;-)

> [1] https://lore.kernel.org/r/20240611074846.1.Ieb287c2c3ee3f6d3b0d5f49b29f746b93621749c@changeid
>
> I will also note that the subject/description of this patch could be
> adjusted. They still reference "drm_helper_force_disable_all" which
> should have been changed to "drm_atomic_helper_shutdown".

Thanks, v3 sent.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds