linux-kernel - Re: [PATCH] cs5535_gpio: gpio_chip.get should return the input value

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Message-Id: <20100224200559.fa911282.akpm@linux-foundation.org>
Date:	Wed, 24 Feb 2010 20:05:59 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Ben Gardner <gardner.ben@...il.com>
Cc:	Andres Salomon <dilinger@...labora.co.uk>,
	linux-kernel@...r.kernel.org, stable@...nel.org
Subject: Re: [PATCH] cs5535_gpio: gpio_chip.get should return the input
 value

On Wed, 24 Feb 2010 21:52:07 -0600 Ben Gardner <gardner.ben@...il.com> wrote:

> >> --- linux-2.6.33-rc8.orig/drivers/gpio/cs5535-gpio.c
> >> +++ linux-2.6.33-rc8/drivers/gpio/cs5535-gpio.c
> >> @@ -154,7 +154,7 @@
> >>
> >> __static int chip_gpio_get(struct gpio_chip *chip, unsigned offset)
> >> __{
> >> - __ __ return cs5535_gpio_isset(offset, GPIO_OUTPUT_VAL);
> >> + __ __ return cs5535_gpio_isset(offset, GPIO_READ_BACK);
> >> __}
> >>
> >> __static void chip_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
> >
> > <presses F10>
> >
> > What were the user-visible effects of this bug?
> 
> The user-visible effects were that the input didn't work.
> I use the CS5535 chip in a custom board that uses GPIO 25 and 26 as
> voltage monitoring inputs (external voltage comparators).
> Since the char-based cs5535-gpio is now deprecated, I'm trying out the
> gpio driver.
> I export the GPIO pins via sysfs to access them from user-space.
> Reading the 'value' member didn't reflect the input.

OK, then in that case we'd want to backport this into 2.6.33.x and
perhaps earlier?

> Personally, I would prefer a separate sysfs entry for the output and
> the input, since the GPIO pins can be both outputs and inputs, but
> that would require a gpiolib change.
> Since there doesn't appear to be a gpio maintainer, any change to that
> might be tricky.

Eh, we can cope.  Propose a patch and cc lots of people..
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