linux-kernel - Re: [PATCH v5 4/4] gpio: rockchip: Set input direction when request irq

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Message-ID: <qwlya3kten7ugxzruohmbmmymjd6trz3rlbflirr3yym2vfe32@rapst33wknmd>
Date: Tue, 12 Nov 2024 14:22:55 +0100
From: Sebastian Reichel <sebastian.reichel@...labora.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	Ye Zhang <ye.zhang@...k-chips.com>, linus.walleij@...aro.org, heiko@...ech.de, 
	linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org, mika.westerberg@...ux.intel.com, 
	tao.huang@...k-chips.com, finley.xiao@...k-chips.com, tim.chen@...k-chips.com, 
	elaine.zhang@...k-chips.com
Subject: Re: [PATCH v5 4/4] gpio: rockchip: Set input direction when request
 irq

Hi,

On Tue, Nov 12, 2024 at 01:53:48PM +0100, Bartosz Golaszewski wrote:
> On Tue, Nov 12, 2024 at 1:50 PM Bartosz Golaszewski <brgl@...ev.pl> wrote:
> > On Tue, Nov 12, 2024 at 11:40 AM Andy Shevchenko
> > <andriy.shevchenko@...ux.intel.com> wrote:
> > > On Tue, Nov 12, 2024 at 09:48:06AM +0100, Bartosz Golaszewski wrote:
> > > > On Tue, Nov 12, 2024 at 2:54 AM Ye Zhang <ye.zhang@...k-chips.com> wrote:
> > > > >
> > > > > Since the GPIO can only generate interrupts when its direction is set to
> > > > > input, it is set to input before requesting the interrupt resources.
> > >
> > > ...
> > >
> > > > This looks like a fix to me, do you want it sent for stable? If so,
> > > > please add the Fixes tag and put it first in the series.
> > >
> > > Independently on the resolution on this, can the first three be applied to
> > > for-next? I think they are valuable from the documentation perspective as
> > > it adds the explanation of the version register bit fields.
> > >
> > > The last one seems to me independent (code wise, meaning no potential
> > > conflicts) to the rest and may be applied to for-current later on.
> > >
> > > --
> > > With Best Regards,
> > > Andy Shevchenko
> > >
> > >
> >
> > There's another issue I see with this patch. It effectively changes
> > the pin's direction behind the back of the GPIOLIB. If a GPIO is
> > requested, its direction set to output and another orthogonal user
> > requests the same pin as input, we'll never update the FLAG_IS_OUT
> 
> I meant to say "same pin as interrupt". Sorry for the noise.

GPIO output and interrupt at the same time looks like a misconfiguration
to me. Maybe check for that situation and return -EBUSY?

-- Sebastian

> 
> Bart
> 
> > value and I don't think any subsequent behavior can be considered
> > defined.
> >
> > I applied the first 3 patches as they look alright.
> >
> > Bart

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