Re: [PATCH v3 3/6] gpio: max77620: Don't set of_node

Dmitry Osipenko
2020-07-08T21:44:39Z

08.07.2020 23:57, Andy Shevchenko пишет:
>
>
> On Wednesday, July 8, 2020, Dmitry Osipenko <digetx@gmail.com
> <mailto:digetx@gmail.com>> wrote:
>
> The gpiochip_add_data() takes care of setting the of_node to the
> parent's
> device of_node, hence there is no need to do it manually in the driver's
> code. This patch corrects the parent's device pointer and removes the
> unnecessary setting of the of_node.
>
>
> 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". 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.

> Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com
> <mailto:andy.shevchenko@gmail.com>>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com
> <mailto:digetx@gmail.com>>
> ---
>  drivers/gpio/gpio-max77620.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/gpio/gpio-max77620.c b/drivers/gpio/gpio-max77620.c
> index 7f7e8d4bf0d3..39d431da2dbc 100644
> --- a/drivers/gpio/gpio-max77620.c
> +++ b/drivers/gpio/gpio-max77620.c
> @@ -279,7 +279,7 @@ static int max77620_gpio_probe(struct
> platform_device *pdev)
>         mgpio->dev = &pdev->dev;
>
>         mgpio->gpio_chip.label = pdev->name;
> -       mgpio->gpio_chip.parent = &pdev->dev;
> +       mgpio->gpio_chip.parent = pdev->dev.parent;
>         mgpio->gpio_chip.direction_input = max77620_gpio_dir_input;
>         mgpio->gpio_chip.get = max77620_gpio_get;
>         mgpio->gpio_chip.direction_output = max77620_gpio_dir_output;
> @@ -288,9 +288,6 @@ static int max77620_gpio_probe(struct
> platform_device *pdev)
>         mgpio->gpio_chip.ngpio = MAX77620_GPIO_NR;
>         mgpio->gpio_chip.can_sleep = 1;
>         mgpio->gpio_chip.base = -1;
> -#ifdef CONFIG_OF_GPIO
> -       mgpio->gpio_chip.of_node = pdev->dev.parent->of_node;
> -#endif
>
>         platform_set_drvdata(pdev, mgpio);
>
> --
> 2.26.0
>
>
>
> --
> With Best Regards,
> Andy Shevchenko
>
>