linux-kernel - Re: [PATCH] Input: elan_i2c: Disable irq on shutdown

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Date:   Thu, 3 Jun 2021 11:53:28 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        Jingle Wu <jingle.wu@....com.tw>, Wolfram Sang <wsa@...nel.org>
Subject: Re: [PATCH] Input: elan_i2c: Disable irq on shutdown

On Wed, Jun 02, 2021 at 11:13:40PM -0700, Stephen Boyd wrote:
> Quoting Dmitry Torokhov (2021-06-02 21:33:41)
> > On Wed, Jun 02, 2021 at 06:33:49PM -0700, Stephen Boyd wrote:
> > > Quoting Dmitry Torokhov (2021-06-02 18:18:17)
> > > >
> > > > I do not think keeping counter balanced would be important here, as we
> > > > are shutting down, and upon reboot everything will be reinitialized from
> > > > scratch. Also, we are lucky in that there is just a handful of I2C
> > > > drivers defining shutdown() methods.
> > > >
> > > > > Please don't make me shave this yak.
> > > >
> > > > I'm afraid someone has to... I'm adding Wolfram to CC to get his take on
> > > > this.
> > > >
> > >
> > > I suppose another option would be to introduce some common function that
> > > i2c drivers can use for their shutdown op, like i2c_generic_shutdown()
> > > that would disable the irq? I would guess that it isn't a great idea to
> > > blanket disable the irq in case some i2c driver wants to do something
> > > that may require that irq to come in once more during shutdown to signal
> > > that things are off or something like that.
> > >
> > > Would having this common function that this driver opts into work for
> > > you?
> >
> > Opting in in this fashion will still require changes in the majority
> > of drivers (any I2C touchscreen or touchpad may be touched while system
> > is being shut down, so all of them will need to have interrupt freed or
> > disabled, or they may initiate I2C transfer). How about something like
> > this;
> 
> Yes, this approach should work. I assume a device that doesn't have a
> shutdown function will be happy to let the i2c core disable the irq for
> it so it looks low risk.
> 
> Will you send a proper patch to Wolfram or would you like me to wrap it
> up and resend?

If you could do that I'd be more than happy.

Thanks.

-- 
Dmitry