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

Commit Message

Geert Uytterhoeven May 29, 2024, 12:16 p.m. UTC

From: Douglas Anderson <[e-mail]>

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 <[e-mail]>
Signed-off-by: Douglas Anderson <[e-mail]>
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 <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
---
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(+)

Comments

Sui Jingfeng May 29, 2024, 4:03 p.m. UTC | #1

Hi,


On 2024/5/29 20:16, Geert Uytterhoeven wrote:
> From: Douglas Anderson <[e-mail]>
>
> 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.


True, looks safer.


> Suggested-by: Maxime Ripard <[e-mail]>
> Signed-off-by: Douglas Anderson <[e-mail]>
> 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 <[e-mail]>
> Reviewed-by: Laurent Pinchart <[e-mail]>

Reviewed-by: Sui Jingfeng <[e-mail]>

Best regards,
Sui

Doug Anderson June 11, 2024, 5:33 p.m. UTC | #2

Hi,

On Wed, May 29, 2024 at 5:16 AM Geert Uytterhoeven
<[e-mail]> wrote:
>
> From: Douglas Anderson <[e-mail]>
>
> 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 <[e-mail]>
> Signed-off-by: Douglas Anderson <[e-mail]>
> 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 <[e-mail]>
> Reviewed-by: Laurent Pinchart <[e-mail]>
> ---
> 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.

[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".

-Doug

Geert Uytterhoeven June 12, 2024, 7:24 a.m. UTC | #3

Hi Doug,

On Tue, Jun 11, 2024 at 7:33 PM Doug Anderson <[e-mail]> wrote:
> On Wed, May 29, 2024 at 5:16 AM Geert Uytterhoeven
> <[e-mail]> wrote:
> >
> > From: Douglas Anderson <[e-mail]>
> >
> > 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 <[e-mail]>
> > Signed-off-by: Douglas Anderson <[e-mail]>
> > 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 <[e-mail]>
> > Reviewed-by: Laurent Pinchart <[e-mail]>
> > ---
> > 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

Patch

diff --git a/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c b/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
index e83c3e52251dedf9..0250d5f00bf102dc 100644
--- a/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
+++ b/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
@@ -171,6 +171,13 @@  static void shmob_drm_remove(struct platform_device *pdev)
 	drm_kms_helper_poll_fini(ddev);
 }
 
+static void shmob_drm_shutdown(struct platform_device *pdev)
+{
+	struct shmob_drm_device *sdev = platform_get_drvdata(pdev);
+
+	drm_atomic_helper_shutdown(&sdev->ddev);
+}
+
 static int shmob_drm_probe(struct platform_device *pdev)
 {
 	struct shmob_drm_platform_data *pdata = pdev->dev.platform_data;
@@ -273,6 +280,7 @@  static const struct of_device_id shmob_drm_of_table[] __maybe_unused = {
 static struct platform_driver shmob_drm_platform_driver = {
 	.probe		= shmob_drm_probe,
 	.remove_new	= shmob_drm_remove,
+	.shutdown	= shmob_drm_shutdown,
 	.driver		= {
 		.name	= "shmob-drm",
 		.of_match_table = of_match_ptr(shmob_drm_of_table),