Re: [PATCH] gpio: fix locking open drain IRQ lines

[Hans Verkuil <hverkuil@xs4all.nl>]

On 27/05/2020 16:07, Linus Walleij wrote:
> We provided the right semantics on open drain lines being
> by definition output but incidentally the irq set up function
> would only allow IRQs on lines that were "not output".
> 
> Fix the semantics to allow output open drain lines to be used
> for IRQs.
> 
> Reported-by: Hans Verkuil <hverkuil@xs4all.nl>

Tested-by: Hans Verkuil <hverkuil@xs4all.nl>

Whether this is the right/best fix or not, I cannot tell, but it certainly
fixes the cec-gpio driver!

Regards,

	Hans

> Cc: Russell King <linux@armlinux.org.uk>
> Cc: stable@vger.kernel.org
> Fixes: 256efaea1fdc ("gpiolib: fix up emulated open drain outputs")
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  drivers/gpio/gpiolib.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index b4b5792fe2ff..edd74ff31cea 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -4220,7 +4220,9 @@ int gpiochip_lock_as_irq(struct gpio_chip *gc, unsigned int offset)
>  		}
>  	}
>  
> -	if (test_bit(FLAG_IS_OUT, &desc->flags)) {
> +	/* To be valid for IRQ the line needs to be input or open drain */
> +	if (test_bit(FLAG_IS_OUT, &desc->flags) &&
> +	    !test_bit(FLAG_OPEN_DRAIN, &desc->flags)) {
>  		chip_err(gc,
>  			 "%s: tried to flag a GPIO set as output for IRQ\n",
>  			 __func__);
>