linux-kernel - Re: [PATCH] simplefb: Disable and release clocks and regulators in destroy callback

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Date:   Wed, 7 Sep 2016 13:29:50 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Chen-Yu Tsai <wens@...e.org>
Cc:     Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] simplefb: Disable and release clocks and regulators in
 destroy callback

Hi,

On 07-09-16 13:12, Geert Uytterhoeven wrote:
> On Wed, Sep 7, 2016 at 11:09 AM, Chen-Yu Tsai <wens@...e.org> wrote:
>> simplefb gets unregister when a proper framebuffer driver comes in and
>> kicks it out. However the claimed clocks and regulators stay enabled
>> as they are only released in the platform device remove function, which
>> in theory would never get called.
>>
>> Move the clock/regulator cleanup into the framebuffer destroy callback,
>> which gets called as part of the framebuffer unregister process.
>
> Is this called before or after the new proper framebuffer driver kicks in?
> If before, it may cause glitches.

It is called by the new proper framebuffer driver's probe method,
so it can make sure that it has already claimed / enabled the
clocks/regulators before it calls remove_conlicting_framebuffers,
avoiding the glitch.

Regards,

Hans