Re: [PATCH v4 02/15] gpio: regmap: set gpio_chip of_node

From: "Álvaro Fernández Rojas" <noltari@gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Linus Walleij <linus.walleij@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>,
	Michael Walle <michael@walle.cc>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>,
	Jonas Gorski <jonas.gorski@gmail.com>,
	Necip Fazil Yildiran <fazilyildiran@gmail.com>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	devicetree <devicetree@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v4 02/15] gpio: regmap: set gpio_chip of_node
Date: Thu, 4 Mar 2021 16:44:47 +0100	[thread overview]
Message-ID: <68F60F3F-33DD-4183-84F9-8D62BFA8A8F1@gmail.com> (raw)
In-Reply-To: <CAHp75VdkCxBeh_cWwN9dKRpEMntMp22yVjWRCuYumhMzrWi+SA@mail.gmail.com>

> El 4 mar 2021, a las 16:28, Andy Shevchenko <andy.shevchenko@gmail.com> escribió:
> 
> On Thu, Mar 4, 2021 at 5:24 PM Álvaro Fernández Rojas <noltari@gmail.com> wrote:
>>> El 4 mar 2021, a las 16:17, Andy Shevchenko <andy.shevchenko@gmail.com> escribió:
>>> On Thu, Mar 4, 2021 at 5:06 PM Álvaro Fernández Rojas <noltari@gmail.com> wrote:
>>>>> El 4 mar 2021, a las 11:35, Andy Shevchenko <andy.shevchenko@gmail.com> escribió:
>>>>> On Thu, Mar 4, 2021 at 10:57 AM Álvaro Fernández 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’t dealt with fwnode never :$
>>>> BTW, this is done to fix this check when parsing gpio ranges:
>>>> https://github.com/torvalds/linux/blob/f69d02e37a85645aa90d18cacfff36dba370f797/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.shevchenko@linux.intel.com/T/#u).

Well that doesn’t fulfill my definition of “current gpiolib-of code”…
@Linus what should I do about this?

> 
>>> 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 one probed (gpio regmap is probed from the pin controller).
>> Therefore the parent’s 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).
> 
> 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/Noltari/linux/blob/6d1ebb8ff26ed54592eef1fcd3b58834acb48c04/drivers/pinctrl/bcm/pinctrl-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

Basically, I based that part of the code on the ingenic pin controller: https://github.com/torvalds/linux/blob/f69d02e37a85645aa90d18cacfff36dba370f797/drivers/pinctrl/pinctrl-ingenic.c#L2485-L2491
https://github.com/torvalds/linux/blob/f69d02e37a85645aa90d18cacfff36dba370f797/Documentation/devicetree/bindings/pinctrl/ingenic%2Cpinctrl.yaml#L155-L176

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

Best regards,
Álvaro.