linux-kernel - Re: [PATCH 2/8] gpio: zynq: Wakeup gpio controller when it is used as IRQ controller

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Date:   Fri, 11 Jan 2019 15:37:07 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Cc:     Michal Simek <michal.simek@...inx.com>,
        Nava kishore Manne <navam@...inx.com>,
        Josh Cartwright <josh.cartwright@...com>,
        "monstr@...str.eu" <monstr@...str.eu>,
        Peter Crosthwaite <peter.crosthwaite@...inx.com>,
        Borsodi Petr <Petr.Borsodi@...z>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        Rob Herring <robherring2@...il.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Steffen Trumtrar <s.trumtrar@...gutronix.de>,
        Sören Brinkmann <soren.brinkmann@...inx.com>,
        Shubhrajyoti Datta <shubhraj@...inx.com>
Subject: Re: [PATCH 2/8] gpio: zynq: Wakeup gpio controller when it is used as
 IRQ controller

On Fri, Jan 11, 2019 at 1:54 PM Thomas Petazzoni
<thomas.petazzoni@...tlin.com> wrote:
> On Fri, 11 Jan 2019 10:54:20 +0100, Linus Walleij wrote:
>
> > My stance is that the driver is responsible of enabling and managing
> > runtime PM for its hardware block(s).
> >
> > Runtime PM in the core should only be added if the core needs to
> > be aware about it, such as is the case when e.g. a block device
> > needs to drain its write buffer before going to runtime sleep.
> >
> > I fail so see why the GPIO core need to be aware about this.
>
> In this very same thread at
> https://www.spinics.net/lists/arm-kernel/msg600515.html, you kind of
> proposed to handle this in the core in fact :-) Though indeed you said
> that the core could provide helpers.

Yeah allright, I have never been good with consistency but what I guess
I would mean to say (today) is that the driver needs to be in the driver
seat (heh) and opting in to any runtime PM support.

This is in contrast with "midlayer" where all drivers are forced to behave
"as if" they had runtime PM (i.e. calls are done to the runtime PM helpers
even if the device doesn't really activate runtime PM).

Yours,
Linus Walleij