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

[Doug Anderson]

Hi,

On Mon, May 24, 2021 at 1:22 PM Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxx>
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>

Thanks! I have pushed just this patch for now.

-Doug