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From: Andy Shevchenko <andy.shevchenko@gmail.com>
Date: Wed, 24 Apr 2024 20:31:27 +0300
Message-ID: <CAHp75VejwJ7h5jaNL+VL7FE4UMbTEP3QA1E=_y-1PSrz99zBKQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/6] iio: light: stk3310: Implement vdd supply and
 power it off during suspend
To: =?UTF-8?Q?Ond=C5=99ej_Jirman?= <megi@xff.cz>, 
	Andy Shevchenko <andy.shevchenko@gmail.com>, Aren Moynihan <aren@peacevolution.org>, 
	Jonathan Cameron <jic23@kernel.org>, Lars-Peter Clausen <lars@metafoo.de>, Rob Herring <robh@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	Chen-Yu Tsai <wens@csie.org>, Jernej Skrabec <jernej.skrabec@gmail.com>, 
	Samuel Holland <samuel@sholland.org>, Liam Girdwood <lgirdwood@gmail.com>, 
	Mark Brown <broonie@kernel.org>, =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= <u.kleine-koenig@pengutronix.de>, 
	linux-iio@vger.kernel.org, phone-devel@vger.kernel.org, 
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, 
	Willow Barraco <contact@willowbarraco.fr>
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On Wed, Apr 24, 2024 at 7:14=E2=80=AFPM Ond=C5=99ej Jirman <megi@xff.cz> wr=
ote:
> On Wed, Apr 24, 2024 at 06:20:41PM GMT, Andy Shevchenko wrote:
> > On Wed, Apr 24, 2024 at 3:59=E2=80=AFPM Ond=C5=99ej Jirman <megi@xff.cz=
> wrote:
> > > On Wed, Apr 24, 2024 at 02:16:06AM GMT, Andy Shevchenko wrote:
> > > > On Wed, Apr 24, 2024 at 1:41=E2=80=AFAM Aren Moynihan <aren@peacevo=
lution.org> wrote:

..

> > > > >         ret =3D stk3310_init(indio_dev);
> > > > >         if (ret < 0)
> > > > > -               return ret;
> > > > > +               goto err_vdd_disable;
> > > >
> > > > This is wrong. You will have the regulator being disabled _before_
> > > > IRQ. Note, that the original code likely has a bug which sets state=
s
> > > > before disabling IRQ and removing a handler.
> > >
> > > How so? stk3310_init is called before enabling the interrupt.
> >
> > Exactly, IRQ is registered with devm and hence the error path and
> > remove stages will got it in a wrong order.
>
> Makes no sense.

Huh?!

> IRQ is not enabled here, yet. So in error path, the code will
> just disable the regulator and devm will unref it later on. IRQ doesn't e=
nter
> the picture here at all in the error path.

Error path _after_ IRQ handler has been _successfully_ installed.
And complete ->remove() stage.

> > > Original code has a bug that IRQ is enabled before registering the
> > > IIO device,
> >
> > Indeed, but this is another bug.
> >
> > > so if IRQ is triggered before registration, iio_push_event
> > > from IRQ handler may be called on a not yet registered IIO device.
> > >
> > > Never saw it happen, though. :)
> >
> > Because nobody cares enough to enable DEBUG_SHIRQ.
>
> Nice debug tool. I bet it makes quite a mess when enabled. :)

FWIW, I have had it enabled for ages, but I have only a few devices,
so I fixed a few cases in the past WRT shared IRQ issues.

--=20
With Best Regards,
Andy Shevchenko