linux-kernel - Re: [PATCH v1 1/1] gpiolib: Read "gpio-line-names" from a firmware node

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Date:   Fri, 5 Mar 2021 13:26:45 +0100
From:   Marek Vasut <marex@...x.de>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Roman Guskov <rguskov@...electronics.com>
Subject: Re: [PATCH v1 1/1] gpiolib: Read "gpio-line-names" from a firmware
 node

On 3/5/21 1:24 PM, Andy Shevchenko wrote:
> On Fri, Mar 05, 2021 at 01:11:39PM +0100, Marek Vasut wrote:
>> On 3/5/21 1:02 PM, Andy Shevchenko wrote:
>>> On STM32MP1, the GPIO banks are subnodes of pin-controller@...02000,
>>> see arch/arm/boot/dts/stm32mp151.dtsi. The driver for
>>> pin-controller@...02000 is in drivers/pinctrl/stm32/pinctrl-stm32.c
>>> and iterates over all of its DT subnodes when registering each GPIO
>>> bank gpiochip. Each gpiochip has:
>>>
>>>     - gpio_chip.parent = dev,
>>>       where dev is the device node of the pin controller
>>>     - gpio_chip.of_node = np,
>>>       which is the OF node of the GPIO bank
>>>
>>> Therefore, dev_fwnode(chip->parent) != of_fwnode_handle(chip.of_node),
>>> i.e. pin-controller@...02000 != pin-controller@...02000/gpio@...0*000.
>>>
>>> The original code behaved correctly, as it extracted the "gpio-line-names"
>>> from of_fwnode_handle(chip.of_node) = pin-controller@...02000/gpio@...0*000.
>>>
>>> To achieve the same behaviour, read property from the firmware node.
>>>
>>> Fixes: 7cba1a4d5e162 ("gpiolib: generalize devprop_gpiochip_set_names() for device properties")
>>> Reported-by: Marek Vasut <marex@...x.de>
>>> Reported-by: Roman Guskov <rguskov@...electronics.com>
>>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>>
>> Tested-by: Marek Vasut <marex@...x.de>
>> Reviewed-by: Marek Vasut <marex@...x.de>
> 
> Thanks!
> 
>> Thanks
>>
>>>    static int devprop_gpiochip_set_names(struct gpio_chip *chip)
>>>    {
>>>    	struct gpio_device *gdev = chip->gpiodev;
>>> -	struct device *dev = chip->parent;
>>> +	struct fwnode_handle *fwnode = dev_fwnode(&gdev->dev);
>>
>> You could make the order here a reverse xmas tree, but that's a nitpick.
> 
> They are dependent, can't be reordered.

Doh, you're right.