Re: [PATCH stable] gpiolib: Read "gpio-line-names" from a firmware node

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On 4/10/21 2:07 PM, Greg Kroah-Hartman wrote:
On Sat, Apr 10, 2021 at 11:09:19AM +0200, Bartosz Golaszewski wrote:
From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

On STM32MP1, the GPIO banks are subnodes of pin-controller@50002000,
see arch/arm/boot/dts/stm32mp151.dtsi. The driver for
pin-controller@50002000 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@50002000 != pin-controller@50002000/gpio@5000*000.

The original code behaved correctly, as it extracted the "gpio-line-names"
from of_fwnode_handle(chip.of_node) = pin-controller@50002000/gpio@5000*000.

To achieve the same behaviour, read property from the firmware node.

Fixes: 7cba1a4d5e162 ("gpiolib: generalize devprop_gpiochip_set_names() for device properties")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Marek Vasut <marex@xxxxxxx>
Reported-by: Roman Guskov <rguskov@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Tested-by: Marek Vasut <marex@xxxxxxx>
Reviewed-by: Marek Vasut <marex@xxxxxxx>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
---
Hi Greg,

This patch somehow got lost and never made its way into stable. Could you
please apply it?

This has been added and removed more times than I can remember already.

Are you all _SURE_ this is safe for a stable kernel release?  Look in
the archives for complaints when we added this in the past.

I now tested this on stm32mp1, which was the original platform that got affected by the problem this is supposed to fix, and I can confirm this patch fixes the problem there.

So for what it's worth
Tested-by: Marek Vasut <marex@xxxxxxx> # on stm32mp1



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