lkml.org 
[lkml]   [2018]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] gpiolib: Show correct direction from the beginning
On Fri, Sep 14, 2018 at 12:08 AM Ricardo Ribalda Delgado
<ricardo.ribalda@gmail.com> wrote:

> Current code assumes that the direction is input if direction_input
> function is set.
> This might not be the case on GPIOs with programmable direction.
>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> ---
> drivers/gpio/gpiolib.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index a57300c1d649..af853749e0bb 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1352,7 +1352,12 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
> * it does, and in case chip->get_direction is not set, we may
> * expose the wrong direction in sysfs.
> */
> - desc->flags = !chip->direction_input ? (1 << FLAG_IS_OUT) : 0;
> + if (chip->get_direction)
> + desc->flags = !chip->get_direction(chip, i) ?
> + (1 << FLAG_IS_OUT) : 0;
> + else
> + desc->flags = !chip->direction_input ?
> + (1 << FLAG_IS_OUT) : 0;

We used to do this.

But it breaks Qualcomm hardware.

commit 1ca2a92b2a99323f666f1b669b7484df4bda05e4
Author: Timur Tabi <timur@codeaurora.org>
Date: Wed Dec 20 13:10:31 2017 -0600

Revert "gpio: set up initial state from .get_direction()"

This reverts commit 72d3200061776264941be1b5a9bb8e926b3b30a5.

We cannot blindly query the direction of all GPIOs when the pins are
first registered. The get_direction callback normally triggers a
read/write to hardware, but we shouldn't be touching the hardware for
an individual GPIO until after it's been properly claimed.

Signed-off-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

\
 
 \ /
  Last update: 2018-09-19 00:41    [W:0.063 / U:10.556 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site