On Thu, Feb 20, 2020 at 12:18 AM Linus Walleij [off-list ref] 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?

Haven't done any GPIO hogging on sx150x, unfortunately. My use-cases were:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/vf610-zii-dev-rev-c.dts

and

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/vf610-zii-scu4-aib.dts

which didn't have any hogs so far (there's a chance Russell is using
the former for his experiments, so maybe that'll change). I don't any
useful input on this regression, sorry. I do have Rev C. board readily
available, so I can provide Tested-by's if I am CC'd on fixes.

Thanks,
Andrey Smirnov

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