Re: [PATCH] gpio: nomadik: Back out some managed resources

[Théo Lebrun <theo.lebrun@xxxxxxxxxxx>]

Hello,

On Tue Mar 5, 2024 at 9:26 AM CET, Linus Walleij wrote:
> Several commits introduce managed resources (devm_*) into the
> nmk_gpio_populate_chip() function.
>
> This isn't always working because when called from the Nomadik pin
> control driver we just want to populate some states for the device as
> the same states are used by the pin control driver.
>
> Some managed resources such as devm_kzalloc() etc will work, as the
> passed in platform device will be used for lifecycle management,
> but in some cases where we used the looked-up platform device
> for the GPIO block, this will cause problems for the combined
> pin control and GPIO driver, because it adds managed resources
> to the GPIO device before it is probed, which is something that
> the device core will not accept, and all of the GPIO blocks will
> refuse to probe:
>
> platform 8012e000.gpio: Resources present before probing
> platform 8012e080.gpio: Resources present before probing
> (...)
>
> Fix this by not tying any managed resources to the looked-up
> gpio_pdev/gpio_dev device, let's just live with the fact that
> these need imperative resource management for now.
>
> Drop in some notes and use a local *dev variable to clarify the
> code.
>
> Cc: Théo Lebrun <theo.lebrun@xxxxxxxxxxx>
> Fixes: 12410e95903c ("gpio: nomadik: use devm_platform_ioremap_resource() helper")
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Thanks Linus for this follow-up. Makes complete sense. Tested on
Mobileye hardware.

This nmk_gpio_populate_chip() function being called by two different
platform drivers makes for a complex setup. I should have been more
wary when modifying it.

Tested-by: Théo Lebrun <theo.lebrun@xxxxxxxxxxx>

Regards,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com