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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Thu, 4 Mar 2021 18:33:24 +0200
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Subject: Re: [PATCH v4 02/15] gpio: regmap: set gpio_chip of_node
To:     =?UTF-8?B?w4FsdmFybyBGZXJuw6FuZGV6IFJvamFz?= <noltari@gmail.com>
Cc:     Linus Walleij <linus.walleij@linaro.org>,
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On Thu, Mar 4, 2021 at 5:44 PM =C3=81lvaro Fern=C3=A1ndez Rojas <noltari@gm=
ail.com> wrote:
> > El 4 mar 2021, a las 16:28, Andy Shevchenko <andy.shevchenko@gmail.com>=
 escribi=C3=B3:
> > On Thu, Mar 4, 2021 at 5:24 PM =C3=81lvaro Fern=C3=A1ndez Rojas <noltar=
i@gmail.com> wrote:
> >>> El 4 mar 2021, a las 16:17, Andy Shevchenko <andy.shevchenko@gmail.co=
m> escribi=C3=B3:
> >>> On Thu, Mar 4, 2021 at 5:06 PM =C3=81lvaro Fern=C3=A1ndez Rojas <nolt=
ari@gmail.com> wrote:
> >>>>> El 4 mar 2021, a las 11:35, Andy Shevchenko <andy.shevchenko@gmail.=
com> escribi=C3=B3:
> >>>>> On Thu, Mar 4, 2021 at 10:57 AM =C3=81lvaro Fern=C3=A1ndez Rojas
> >>>>> <noltari@gmail.com> wrote:
> >>>
> >>>>>> + * @of_node:           (Optional) The device node
> >>>>>
> >>>>>> +       struct device_node *of_node;
> >>>>>
> >>>>> Can we use fwnode from day 1, please?
> >>>>
> >>>> Could you explain this? I haven=E2=80=99t dealt with fwnode never :$
> >>>> BTW, this is done to fix this check when parsing gpio ranges:
> >>>> https://github.com/torvalds/linux/blob/f69d02e37a85645aa90d18cacfff3=
6dba370f797/drivers/gpio/gpiolib-of.c#L933-L934
> >>>
> >>> Use struct fwnode_handle pointer instead of OF-specific one.
> >>
> >> But is that compatible with the current gpiolib-of code? :$
> >
> > Yes (after a bit of amendment I have sent today as v2:
> > https://lore.kernel.org/linux-gpio/20210304150215.80652-1-andriy.shevch=
enko@linux.intel.com/T/#u).
>
> Well that doesn=E2=80=99t fulfill my definition of =E2=80=9Ccurrent gpiol=
ib-of code=E2=80=9D=E2=80=A6
> @Linus what should I do about this?

Well, fwnode is a generic, and I strongly against spreading
OF-specific code when we have fwnode working. But let's hear Linus
out, of course!

But it seems you are right and the library needs a few more amendments.

> >>> Also here is the question, why do you need to have that field in the
> >>> regmap config structure and can't simply use the parent's fwnode?
> >>> Also I'm puzzled why it's not working w/o this patch: GPIO library
> >>> effectively assigns parent's fwnode (okay, of_node right now).
> >>
> >> Because gpio regmap a child node of the pin controller, which is the o=
ne probed (gpio regmap is probed from the pin controller).
> >> Therefore the parent=E2=80=99s fwnode is useless, since the correct gp=
io_chip node is the child's one (we have pin-ranges declared in the child n=
ode, referencing the parent pinctrl node).
> >
> > I see. Can you point me out to the code where we get the node and
> > where it's being retrieved / filled?
>
> Sure, this is where the child node is searched: https://github.com/Noltar=
i/linux/blob/6d1ebb8ff26ed54592eef1fcd3b58834acb48c04/drivers/pinctrl/bcm/p=
inctrl-bcm63xx.c#L100-L109
> Then the gpio child node is probed and assigned here: https://github.com/=
Noltari/linux/blob/6d1ebb8ff26ed54592eef1fcd3b58834acb48c04/drivers/pinctrl=
/bcm/pinctrl-bcm63xx.c#L51

So, this is not (*yet) in upstream, correct?

So, why not to switch to fwnode API in that driver as well?

When you do that and supply fwnode thru the regmap configuration, in
the gpio-regmap we may assign it to of_node (via to_of_node() API).

> Basically, I based that part of the code on the ingenic pin controller: h=
ttps://github.com/torvalds/linux/blob/f69d02e37a85645aa90d18cacfff36dba370f=
797/drivers/pinctrl/pinctrl-ingenic.c#L2485-L2491
> https://github.com/torvalds/linux/blob/f69d02e37a85645aa90d18cacfff36dba3=
70f797/Documentation/devicetree/bindings/pinctrl/ingenic%2Cpinctrl.yaml#L15=
5-L176

This doesn't use remgap GPIO.

--=20
With Best Regards,
Andy Shevchenko