Re: pinctrl: qcom: ipq4019: Use of gpio-hog's

[Christian Lamparter <chunkeey@xxxxxxxxx>]

On Dienstag, 27. März 2018 10:41:46 CEST Sven Eckelmann wrote:
> On Montag, 26. März 2018 20:39:39 CEST Christian Lamparter wrote:
> [...]
> > > What is the correct way for qcom,ipq4019-pinctrl to configure a pin during 
> > > bootup (gpio-hog)? I can use the deprecated gpio sysfs infrastructure for
> > > now but this seems to be only a dirty hack.
> > > 
> > I found the bug/issue and it's sort of specific to OF, pinctrl and gpio-hog.
> > 
> > However I do think that all pinctrl drivers are affect that call
> > gpiochip_add_pin_range() *after* (devm_)gpiochip_add_data().
> [...]
> > For ipq4019 (and all the others too?), there is this an workaround
> > that can be done:
> > 
> > Add the gpio-ranges property to the pinctrl node in the qcom-ipq4019.dtsi:
> > 
> > tlmm: pinctrl@1000000 {
> >         gpio-ranges = <&tlmm 0 0 99>;
> > };
> > 
> > and remove the gpiochip_add_pin_range() call in:
> > <https://elixir.bootlin.com/linux/v4.16-rc7/source/drivers/pinctrl/qcom/pinctrl-msm.c#L834>
> [...]
> 
> Thanks a lot for investigating this. I think this be discussed first by the 
> maintainers. Also Benoit Parrot should be asked here [1] because he integrated 
> the gpio-hog support for gpiolib-of.

Hm, It could be a moot point. I found this e-mail form @Linus Walleij
<http://comments.gmane.org/gmane.linux.ports.arm.kernel/184816>

Where he stated that he wanted the "gpiochip_add_pin_range()" functions
|[...]
|But I want two similar function named:
|
|gpiochip_add_pin_range();
|gpiochip_remove_pin_range();
|
|*that can be used for platforms that doesn't support DT.*

so, gpiochip_add_pin_range() was not meant to be used by DT platforms.

Now, converting pinctrl-msm.c would involve updating the .dtsi files
of various Qcom SoCs. This is easy enough, but there is an issue; not
all platforms have a upstream device-tree source files: 
the qcom-msm8998.dtsi is MIA / (well, Bjorn seems to upstream it at 
the moment?).

Regards,
Christian
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