diff mbox series

[v7,01/10] drm/panel: panel-simple: Add missing pm_runtime_dont_use_autosuspend() calls

Message ID 20210517130450.v7.1.I9e947183e95c9bd067c9c1d51208ac6a96385139@changeid (mailing list archive)
State Superseded
Headers show
Series drm: Fix EDID reading on ti-sn65dsi86 by introducing the DP AUX bus | expand

Commit Message

Doug Anderson May 17, 2021, 8:08 p.m. UTC
The PM Runtime docs specifically call out the need to call
pm_runtime_dont_use_autosuspend() in the remove() callback if
pm_runtime_use_autosuspend() was called in probe():

> Drivers in ->remove() callback should undo the runtime PM changes done
> in ->probe(). Usually this means calling pm_runtime_disable(),
> pm_runtime_dont_use_autosuspend() etc.

We should do this. This fixes a warning splat that I saw when I was
testing out the panel-simple's remove().

Fixes: 3235b0f20a0a ("drm/panel: panel-simple: Use runtime pm to avoid excessive unprepare / prepare")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v7:
- pm_runtime_dont_use_autosuspend() fix new for v7.

 drivers/gpu/drm/panel/panel-simple.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Laurent Pinchart May 24, 2021, 8:22 p.m. UTC | #1
Hi Doug,

Thank you for the patch.

On Mon, May 17, 2021 at 01:08:58PM -0700, Douglas Anderson wrote:
> The PM Runtime docs specifically call out the need to call
> pm_runtime_dont_use_autosuspend() in the remove() callback if
> pm_runtime_use_autosuspend() was called in probe():
> 
> > Drivers in ->remove() callback should undo the runtime PM changes done
> > in ->probe(). Usually this means calling pm_runtime_disable(),
> > pm_runtime_dont_use_autosuspend() etc.

~/src/kernel/linux $ git grep pm_runtime_use_autosuspend -- drivers | wc -l
209
~/src/kernel/linux $ git grep pm_runtime_dont_use_autosuspend -- drivers | wc -l
80

Seems like a lost battle :-(

The fix is right, but I wonder if this shouldn't be handled
automatically by the runtime PM core. The runtime PM API is notoriously
difficult to use correctly.

> We should do this. This fixes a warning splat that I saw when I was
> testing out the panel-simple's remove().
>
> Fixes: 3235b0f20a0a ("drm/panel: panel-simple: Use runtime pm to avoid excessive unprepare / prepare")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> 
> Changes in v7:
> - pm_runtime_dont_use_autosuspend() fix new for v7.
> 
>  drivers/gpu/drm/panel/panel-simple.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 9be050ab372f..21939d4352cf 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -798,6 +798,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>  	return 0;
>  
>  disable_pm_runtime:
> +	pm_runtime_dont_use_autosuspend(dev);
>  	pm_runtime_disable(dev);
>  free_ddc:
>  	if (panel->ddc)
> @@ -814,6 +815,7 @@ static int panel_simple_remove(struct device *dev)
>  	drm_panel_disable(&panel->base);
>  	drm_panel_unprepare(&panel->base);
>  
> +	pm_runtime_dont_use_autosuspend(dev);
>  	pm_runtime_disable(dev);
>  	if (panel->ddc)
>  		put_device(&panel->ddc->dev);
Doug Anderson May 24, 2021, 9:08 p.m. UTC | #2
Hi,

On Mon, May 24, 2021 at 1:22 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Doug,
>
> Thank you for the patch.
>
> On Mon, May 17, 2021 at 01:08:58PM -0700, Douglas Anderson wrote:
> > The PM Runtime docs specifically call out the need to call
> > pm_runtime_dont_use_autosuspend() in the remove() callback if
> > pm_runtime_use_autosuspend() was called in probe():
> >
> > > Drivers in ->remove() callback should undo the runtime PM changes done
> > > in ->probe(). Usually this means calling pm_runtime_disable(),
> > > pm_runtime_dont_use_autosuspend() etc.
>
> ~/src/kernel/linux $ git grep pm_runtime_use_autosuspend -- drivers | wc -l
> 209
> ~/src/kernel/linux $ git grep pm_runtime_dont_use_autosuspend -- drivers | wc -l
> 80
>
> Seems like a lost battle :-(
>
> The fix is right, but I wonder if this shouldn't be handled
> automatically by the runtime PM core. The runtime PM API is notoriously
> difficult to use correctly.

No kidding.


> > We should do this. This fixes a warning splat that I saw when I was
> > testing out the panel-simple's remove().
> >
> > Fixes: 3235b0f20a0a ("drm/panel: panel-simple: Use runtime pm to avoid excessive unprepare / prepare")
> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Thanks! I have pushed just this patch for now.

-Doug
diff mbox series

Patch

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 9be050ab372f..21939d4352cf 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -798,6 +798,7 @@  static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 	return 0;
 
 disable_pm_runtime:
+	pm_runtime_dont_use_autosuspend(dev);
 	pm_runtime_disable(dev);
 free_ddc:
 	if (panel->ddc)
@@ -814,6 +815,7 @@  static int panel_simple_remove(struct device *dev)
 	drm_panel_disable(&panel->base);
 	drm_panel_unprepare(&panel->base);
 
+	pm_runtime_dont_use_autosuspend(dev);
 	pm_runtime_disable(dev);
 	if (panel->ddc)
 		put_device(&panel->ddc->dev);