linux-kernel - Re: [PATCH] drm/bridge: ti-sn65dsi86: Properly undo autosuspend

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Message-ID: <YhXBIxbx63IXBU7L@pendragon.ideasonboard.com>
Date:   Wed, 23 Feb 2022 07:07:47 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Douglas Anderson <dianders@...omium.org>,
        dri-devel@...ts.freedesktop.org,
        Brian Norris <briannorris@...omium.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: ti-sn65dsi86: Properly undo autosuspend

On Tue, Feb 22, 2022 at 11:44:54PM +0100, Linus Walleij wrote:
> On Tue, Feb 22, 2022 at 11:19 PM Douglas Anderson <dianders@...omium.org> wrote:
> >
> > The PM Runtime docs say:
> >   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 weren't doing that for autosuspend. Let's do it.
> >
> > Fixes: 9bede63127c6 ("drm/bridge: ti-sn65dsi86: Use pm_runtime autosuspend")
> > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> 
> Hm. I know a few places in drivers where I don't do this :/

It seems to be a very common problem indeed, I haven't seen any driver
yet that uses pm_runtime_dont_use_autosuspend(). We could play a game of
whack-a-mole, but we'll never win. Could this be solved in the runtime
PM framework instead ? pm_runtime_disable() could disable auto-suspend.
If there are legitimate use cases for disabling runtime PM temporarily
without disabling auto-suspend, then a new function designed
specifically for remove() that would take care of cleaning everything up
could be another option.

> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

-- 
Regards,

Laurent Pinchart