Re: [PATCH 18/23] gpio: nomadik: support mobileye,eyeq5-gpio

[Théo Lebrun <theo.lebrun@xxxxxxxxxxx>]

Hello,

On Wed Feb 21, 2024 at 8:36 PM CET, Linus Walleij wrote:
> On Wed, Feb 21, 2024 at 5:16 PM Théo Lebrun <theo.lebrun@xxxxxxxxxxx> wrote:
>
> > > Trying to figure it out...
> >
> > Can I help in the debugging process?
>
> Nah, I found it :)
>
> > Reading the code once again I'd guess
> > of_device_get_match_data(&gpio_pdev->dev) could be the root cause. We
> > are accessing match data for the GPIO device while probing the pinctrl
> > device. Maybe something isn't initialised properly yet? The rest looks
> > rather harmless, I've checked all conditional expressions.
>
> Yep spot on. The nmk_gpio_populate_chip() is sometimes called from
> the pinctrl driver before the gpio probe() has been called, so the match
> data is NULL and we crash.
>
> This looks like it does for historical reasons and there could be better
> ways to fix it now that Saravana Kannan has fixed up the probe ordering
> code.
>
> The following is one way to fix it for now using device_is_compatible()
> (illustrating some other changes I did as well):

Thanks for the debugging and the proposed fix. Indeed matching on
compatible to avoid match data for a bool makes sense.

Thanks,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com