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

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)

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?

Yours,
Linus Walleij

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