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SubjectRe: [PATCH v2 1/2] pinctrl: bcm: bcm2835: Switch to use ->add_pin_ranges()
Hi Andy,

Am 13.01.23 um 22:31 schrieb Andy Shevchenko:
> On Fri, Jan 13, 2023 at 09:13:23PM +0100, Stefan Wahren wrote:
>> Am 13.01.23 um 18:10 schrieb Andy Shevchenko:
> ...
>>> v2: fixed compilation issues (LKP), Cc'ed to the author of original code
>>> Btw, the commit d2b67744fd99 ("pinctrl: bcm2835: implement hook for
>>> missing gpio-ranges") seems problematic in the fist place due to
>>> odd of_node_put() call. I dunno how that part had been tested, or
>>> how it's supposed to work, i.e. where is the counterpart of_node_get().
>>> Anyway this change drops it for good.
>> The countpart is in of_pinctrl_get(). I was just following the pattern like
>> in other drivers like gpio-rockchip. The original commit has been tested by
>> Florian Fainelli and me. I'm not sure if it's safe to drop it completely.
> Please, elaborate how of_pinctrl_get() increases refcount of the parameter.
> Maybe I'm looking into a wrong place?
>> Btw this is not the only platform affected by the gpio-ranges compatibility
>> issue [1].
> This is the only one that uses unnecessary added callback.

i didn't have access to any of the other platforms which were also
affected. So i thought providing a general solution would be good idea.
I wasn't aware of add_pin_ranges().

Since i was annoyed that nobody cared about DTB backward compatibility,
i send out a RFC series to fix the GPIO hog regression which breaks the
LEDs on the Raspberry Pi. Nobody complained about it.

>>> Perhaps we can check gpio-ranges property presence inside the GPIO
>>> library, so this ->add_pin_ranges() won't be called at all.
>> I thought this could be very platform specific, so i implemented a hook. But
>> yes my initial hack modified gpiolib-of [2].
> The point is that possibly documentation of ->add_pin_ranges() should be
> amended to take care of the cases like this. We don't need two or more
> hooks to do the same, esp. taking into account that OF specific doesn't
> cover other cases.
>> [1] -
>> [2] -
>>> Also I would like to understand the dance around checking for pin
>>> control device. The original commit lacks of comments in the non-trivial
>>> code.
> Any comment on this?
Do you mean the NULL check? of_pinctrl_get() could return NULL, but
pinctrl_dev_get_devname() directly access the dev member.

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