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Subject: Re: [PATCH v3 3/6] gpio: max77620: Don't set of_node
To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Laxman Dewangan <ldewangan@nvidia.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
        "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <ff7985a4-58be-b466-62c2-abce9ae1c0f0@gmail.com>
Date:   Thu, 9 Jul 2020 13:38:26 +0300
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09.07.2020 12:07, Andy Shevchenko пишет:
> On Thu, Jul 9, 2020 at 12:44 AM Dmitry Osipenko <digetx@gmail.com> wrote:
>> 08.07.2020 23:57, Andy Shevchenko пишет:
>>> On Wednesday, July 8, 2020, Dmitry Osipenko <digetx@gmail.com
>>> <mailto:digetx@gmail.com>> wrote:
> 
> ...
> 
>>> I gave a second look and I think my suggestion is wrong. Here is an
>>> interesting propagation of the parent device node to its grand son,
>>> leaving son’s one untouched. Original code has intentions to do that way.
>>
>> The [1] says that gpio_chip.parent should point at the "device providing
>> the GPIOs".
> 
> Yes, physical device I believe.
> 
>> That's the pdev->dev.parent in the case of this driver.
>> MAX77620 is an MFD PMIC device that has virtual sub-devices like GPIO
>> controller, PINCTRL and RTC. The MFD is the parent device that provides
>> the GPIOs [2].
>>
>> [1]
>> https://elixir.bootlin.com/linux/v5.8-rc3/source/include/linux/gpio/driver.h#L276
>>
>> [2]
>> https://elixir.bootlin.com/linux/v5.8-rc3/source/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi#L48
>>
>> I think the old code was wrong and this patch is correct, please correct
>> me if I'm missing something.
> 
> Hmm... I have checked through GPIO drivers I have knowledge of / care
> about and PMIC ones do like you suggested in this patch, the rest
> (which are instantiated from MFD) take a virtual platform device.
> 
> Looking at DT excerpt I think you're rather right than wrong, so I
> leave it to you and maintainers.
> Thanks!

Okay, waiting for the maintainers then :)

Thank you very much for the review!