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Subject: Re: [PATCH v4 02/15] gpio: regmap: set gpio_chip of_node
From:   =?utf-8?Q?=C3=81lvaro_Fern=C3=A1ndez_Rojas?= <noltari@gmail.com>
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Date:   Fri, 5 Mar 2021 08:45:40 +0100
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
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To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Precedence: bulk

Hi Andy,

> El 4 mar 2021, a las 17:33, Andy Shevchenko =
<andy.shevchenko@gmail.com> escribi=C3=B3:
>=20
> On Thu, Mar 4, 2021 at 5:44 PM =C3=81lvaro Fern=C3=A1ndez Rojas =
<noltari@gmail.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 =
<noltari@gmail.com> wrote:
>>>>> El 4 mar 2021, a las 16:17, Andy Shevchenko =
<andy.shevchenko@gmail.com> escribi=C3=B3:
>>>>> On Thu, Mar 4, 2021 at 5:06 PM =C3=81lvaro Fern=C3=A1ndez Rojas =
<noltari@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:
>>>>>=20
>>>>>>>> + * @of_node:           (Optional) The device node
>>>>>>>=20
>>>>>>>> +       struct device_node *of_node;
>>>>>>>=20
>>>>>>> Can we use fwnode from day 1, please?
>>>>>>=20
>>>>>> 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/f69d02e37a85645aa90d18cacfff36dba37=
0f797/drivers/gpio/gpiolib-of.c#L933-L934
>>>>>=20
>>>>> Use struct fwnode_handle pointer instead of OF-specific one.
>>>>=20
>>>> But is that compatible with the current gpiolib-of code? :$
>>>=20
>>> Yes (after a bit of amendment I have sent today as v2:
>>> =
https://lore.kernel.org/linux-gpio/20210304150215.80652-1-andriy.shevchenk=
o@linux.intel.com/T/#u).
>>=20
>> Well that doesn=E2=80=99t fulfill my definition of =E2=80=9Ccurrent =
gpiolib-of code=E2=80=9D=E2=80=A6
>> @Linus what should I do about this?
>=20
> 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!
>=20
> But it seems you are right and the library needs a few more =
amendments.

Yes, but I=E2=80=99m trying to do as few amendments as possible since I =
already have quite a large amount of patches :)

>=20
>>>>> 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).
>>>>=20
>>>> Because gpio regmap a child node of the pin controller, which is =
the one probed (gpio regmap is probed from the pin controller).
>>>> Therefore the parent=E2=80=99s fwnode is useless, since the correct =
gpio_chip node is the child's one (we have pin-ranges declared in the =
child node, referencing the parent pinctrl node).
>>>=20
>>> I see. Can you point me out to the code where we get the node and
>>> where it's being retrieved / filled?
>>=20
>> Sure, this is where the child node is searched: =
https://github.com/Noltari/linux/blob/6d1ebb8ff26ed54592eef1fcd3b58834acb4=
8c04/drivers/pinctrl/bcm/pinctrl-bcm63xx.c#L100-L109
>> Then the gpio child node is probed and assigned here: =
https://github.com/Noltari/linux/blob/6d1ebb8ff26ed54592eef1fcd3b58834acb4=
8c04/drivers/pinctrl/bcm/pinctrl-bcm63xx.c#L51
>=20
> So, this is not (*yet) in upstream, correct?

No it=E2=80=99s not, but I've already changed the approach several times =
and I=E2=80=99m starting to get tired about it...

>=20
> So, why not to switch to fwnode API in that driver as well?
>=20
> 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).
>=20
>> Basically, I based that part of the code on the ingenic pin =
controller: =
https://github.com/torvalds/linux/blob/f69d02e37a85645aa90d18cacfff36dba37=
0f797/drivers/pinctrl/pinctrl-ingenic.c#L2485-L2491
>> =
https://github.com/torvalds/linux/blob/f69d02e37a85645aa90d18cacfff36dba37=
0f797/Documentation/devicetree/bindings/pinctrl/ingenic%2Cpinctrl.yaml#L15=
5-L176
>=20
> This doesn't use remgap GPIO.

Yes, I know, but there aren=E2=80=99t any pinctrl drivers using regmap =
GPIO right now, so I couldn=E2=80=99t base my code on anything else :)

>=20
> --=20
> With Best Regards,
> Andy Shevchenko

Best regards,
=C3=81lvaro.=