Re: [PATCH] gpiolib: Don't implicitly disable irq when masking

[Linus Walleij]

On Wed, May 10, 2023 at 10:59 PM Chris Packham
<Chris.Packham@xxxxxxxxxxxxxxxxxxx> wrote:

> The coupling of gpiochip_irq_mask()/gpiochip_irq_unmask() with
> gpiochip_disable_irq()/gpiochip_enable_irq() goes back to the same
> commit a8173820f441 ("gpio: gpiolib: Allow GPIO IRQs to lazy disable").
> It's not immediately obvious to me why the coupling is needed.

That is just a refactoring of what existed before.

The use case is here:
drivers/media/cec/platform/cec-gpio/cec-gpio.c

The driver needs to switch, at runtime, between actively driving a GPIO
line with gpiod_set_value(), and setting the same line into input mode
and listening for signalling triggering IRQs on it, and then back to
output mode and driving the line again. It's a bidirectional GPIO line.
This use case yields a high need of control.

> I was
> hoping that someone seeing my patch would confirm that it's not needed
> or say why it's needed suggest an alternative approach.

Which IRQ-enabled gpiochip is this? Has it been converted to be immutable?
I think that could be part of the problem.

Yours,
Linus Walleij