Re: [PATCH RFT 2/6] gpio: mmio: get chip label and GPIO base from device properties

[Krzysztof Kozlowski <krzk@kernel.org>]

On 25/06/2025 12:23, Bartosz Golaszewski wrote:
> On Wed, Jun 25, 2025 at 10:54 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>
>> On 25/06/2025 09:35, Bartosz Golaszewski wrote:
>>> On Tue, 24 Jun 2025 at 21:44, Linus Walleij <linus.walleij@linaro.org> wrote:
>>>>
>>>> On Tue, Jun 24, 2025 at 3:19 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>>>>
>>>>> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>>>>>
>>>>> Ahead of removing struct bgpio_pdata support from the gpio-mmio generic
>>>>> module, let's add support for getting the relevant values from generic
>>>>> device properties. "label" is a semi-standardized property in some GPIO
>>>>> drivers so let's go with it. There's no standard "base" property, so
>>>>> let's use the name "gpio-mmio,base" to tie it to this driver
>>>>> specifically. The number of GPIOs will be retrieved using
>>>>> gpiochip_get_ngpios() so there's no need to look it up in the software
>>>>> node.
>>>>>
>>>>> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>>>>
>>>> This works for me.
>>>> I wouldn't be stoked to see device trees abusing the "gpio-mmio,base"
>>>> property all of a sudden just because it now exists as a device
>>>> property though... I kind of wish we had a way to opt out of exposing
>>>> this to all the sub-property paths. But it seems tiresome, so:
>>>>
>>>> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
>>>>
>>>> Yours,
>>>> Linus Walleij
>>>
>>> That's not a problem - this property is not in any DT bindings and as
>>> such is not an allowed property in DT sources. For out-of-tree DTs? We
>>> don't care about those.
>> That's not true, we do care about implied ABI. Try changing/breaking
>> this later, when users complain their out of tree DTS is affected, and
>> explaining this all to Greg.
>>
> 
> Wait, seriously? I thought that the upstream bindings are the source
> of truth for device-tree sources...


They are, until they are not... ok, we don't really care that much about
out of tree DTS, but in-tree DTS still could use these and don't care
about bindings check, right?

Best regards,
Krzysztof