Re: GPIOLIB locking is broken and how to fix it

[Aaro Koskinen <aaro.koskinen@xxxxxx>]

Hi,

On Mon, Dec 11, 2023 at 04:49:43PM +0100, Bartosz Golaszewski wrote:
> Aaro: do you still have the HW to test this driver?

Yes, and I still use it.

> I understand the need to disable interrupts during writing or reading
> data - when we are driving the clock line. But do we also absolutely
> need to hold the spinlock when setting the direction of the data line
> to input? Because if we don't then we could modify the last remaining
> offender to not set GPIO direction with a spinlock held and finally make
> gpiod_direction_*() functions sleepable.

Hmm, I think it's required to be able to provide atomic xfer function.
That is needed for e.g. for power off.

A.