Re: gpiod_set_value(): BUG: sleeping function called from invalid context

[Petko Manolov <petko.manolov@xxxxxxxxxxxx>]

On 21-12-05 12:59:46, Hans Verkuil wrote:
>

<snip>

> I'm not sure if the pctldev->mutex can be replaced with rcu, I suspect not.

Not in this case. :)

> For something that's supposed to be atomic, there seem to be an awful lot of 
> mutexes...

By looking at the generic gpiolib code, it seems that none of these are supposed 
to be called from atomic context.

> In the case of the bcm2711 the bcm2835_gpio_direction_output() function calls
> pinctrl_gpio_direction_output, which in turn (via pinctrl_gpio_direction()
> and pinmux_gpio_direction()) calls bcm2835_pmx_gpio_set_direction().

Is the aforementioned code mainlined or is it in some other git tree?  I'd like 
to take a quick look.

> It appears to me that bcm2835_gpio_direction_output() can call
> bcm2835_pmx_gpio_set_direction() directly, thus avoiding all the mutexes.
> That's exactly what samsung/pinctrl-samsung.c and qcom/pinctrl-msm.c do,
> from what I can tell.
> 
> Are pinctrl drivers supposed to call pinctrl_gpio_direction_output() from the 
> direction_output() op? Isn't that perhaps the bug?

If direction_output() is supposed to be called from atomic context, then that's 
where the bug is.  Again, i am not familiar with this particular subsystem, but 
these are pretty basic kernel concepts people must pay attention to.  You should 
perhaps focus on Broadcom's code rather than pinctrl's.


		Petko