On 2020-02-20 09:17, Linus Walleij wrote:

On Thu, Feb 6, 2020 at 6:33 PM Russell King - ARM Linux admin
[off-list ref] wrote:

quoted

It seems that sometime between 4.20 and 5.5, something has broken the
ability to specify gpio-hogs in DT for GPIOs that are written around
pinctrl drivers.

(explanation that makes perfect sense)

quoted

Consequently, adding a gpio-hog to DT for this driver results in the
driver endlessly returning -EPROBE_DEFER.

I suspect this is sx150x-specific and suspect these two commits:

1a1d39e1b8dd pinctrl: sx150x: Register pinctrl before adding the gpiochip
b930151e5b55 pinctrl: sx150x: Add a static gpio/pinctrl pin range mapping

I suppose people weren't using hogs very much with the sx150x and
it didn't turn up in testing so far.

I don't think for example pinctrl-stmfx.c has this problem, as it registers
the pin ranges from the device tree as part of the core code.
But other drivers calling gpiochip_add_pin_range() may be experiencing
this.

Peter/Andrey, do you have some idea? Have you tested this usecase (hogs)
with the sx150x?

I have never created gpio hogs myself, so no, I haven't done any testing
with that. Sorry. I could of course spend some time looking at this, but I
don't know all that much about the wrinkles of the interactions between
pinctrl och gpio. Or plain gpio/pinctrl for that matter. Sure, I extended
this driver, but I haven't really looked at those sub-systems since. I
think others will come up with a solution for this with much less effort
and with less risk of introducing new problems...

Cheers,
Peter
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel