linux-kernel - Re: [linux-sunxi] Re: [PATCH] input: sun4i-lradc-keys: Add wakup support

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Message-ID: <20191029124331.7yh5kccsq2syxm47@core.my.home>
Date:   Tue, 29 Oct 2019 13:43:31 +0100
From:   Ondřej Jirman <megous@...ous.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-sunxi@...glegroups.com, Hans de Goede <hdegoede@...hat.com>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        "open list:SUN4I LOW RES ADC ATTACHED TABLET KEYS DRIVER" 
        <linux-input@...r.kernel.org>,
        "moderated list:ARM/Allwinner sunXi SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [linux-sunxi] Re: [PATCH] input: sun4i-lradc-keys: Add wakup
 support

On Mon, Oct 28, 2019 at 09:18:04PM -0700, Dmitry Torokhov wrote:
> On Tue, Oct 29, 2019 at 02:45:59AM +0100, Ondřej Jirman wrote:
> > On Mon, Oct 28, 2019 at 05:12:50PM -0700, Dmitry Torokhov wrote:
> > > On Tue, Oct 29, 2019 at 12:56:26AM +0100, Ondřej Jirman wrote:
> > > > On Mon, Oct 28, 2019 at 04:38:28PM -0700, Dmitry Torokhov wrote:
> > > > > > +
> > > > > > +	error = dev_pm_set_wake_irq(dev, irq);
> > > > > > +	if (error) {
> > > > > > +		dev_err(dev, "Could not set wake IRQ\n");
> > > > > > +		return error;
> > > > > > +	}
> > > > > > +
> > > > > 
> > > > > I wonder if we could teach platform driver core to handle this for us.
> > > > 
> > > > Not sure, some drivers do enable/disable wake_irq by hand in suspend/resume
> > > > callbacks, so it would probably need to be opt-in somehow. I guess calling the
> > > > function like this is one way to make it opt-in.
> > > > 
> > > > The other way may be by passing a flag somewhere, like to
> > > > request_threaded_irq. Did you have something more concrete in mind?
> > > 
> > > I think it is perfectly fine to continue using enable_irq_wake and
> > > disable_irq_wake from the driver while marking irq as being wake irq
> > > form the core.
> > 
> > I see, it looks like irq_set_irq_wake will track the calls via wake_depth
> > 
> > https://elixir.bootlin.com/linux/latest/source/kernel/irq/manage.c#L714
> > 
> > But all irqs are not necessarily wake irqs, no? So it still may need to be
> > opt-in somehow.
> 
> I thought we'd do that for IRQ named "wakeirq" or the very first IRQ if
> there is no named IRQ, and when we have the "wakeup-source" property,
> similarly to what we do in I2C bus.

I see. I've looked at drivers using dev_pm_set_wake_irq and
dev_pm_set_dedicated_wake_irq and not many platform drivers would potentially
benefit (~25 out of 2300), of those only some use OF and are platform
drivers, maybe 15-20:

https://elixir.bootlin.com/linux/latest/ident/dev_pm_set_wake_irq
https://elixir.bootlin.com/linux/latest/ident/dev_pm_set_dedicated_wake_irq

I don't think it's worth it.

regards,
	o.

> Thanks.
> 
> -- 
> Dmitry
> 
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