Re: [PATCH] gpio: allow passing NULL to gpio_request_by_line_name() to search all gpio controllers

[Simon Glass <sjg@chromium.org>]

Hi Rasmus,

On Sun, 19 Mar 2023 at 13:38, Rasmus Villemoes
<rasmus.villemoes@prevas.dk> wrote:
>
> On 18/03/2023 21.20, Simon Glass wrote:
> > Hi Rasmus,
> >
> > On Fri, 17 Mar 2023 at 14:13, Rasmus Villemoes
> > <rasmus.villemoes@prevas.dk> wrote:
> >>
> >> The API is more convenient to use if one doesn't have to know upfront
> >> which gpio controller has a line with the name one is searching for,
> >> and arrange to look that device up somehow. Or implement this loop
> >> oneself.
> >>
> >> Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
> >> ---
> >>  drivers/gpio/gpio-uclass.c | 7 +++++++
> >>  include/asm-generic/gpio.h | 3 ++-
> >>  2 files changed, 9 insertions(+), 1 deletion(-)
> >
> > Reviewed-by: Simon Glass <sjg@chromium.org>
> >
> > What is a line name? I don't see any mention of its purpose in the
> > binding doc[1].
>
> Nah, those yaml-files are usually completely useless to gain some
> understanding of what stuff is for, I much preferred the free-form prose.
>
> https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt
> has this text:
>
> Optionally, a GPIO controller may have a "gpio-line-names" property. This is
> an array of strings defining the names of the GPIO lines going out of the
> GPIO controller. This name should be the most meaningful producer name
> for the system, such as a rail name indicating the usage. Package names
> such as pin name are discouraged: such lines have opaque names (since they
> are by definition generic purpose) and such names are usually not very
> helpful. For example "MMC-CD", "Red LED Vdd" and "ethernet reset" are
> reasonable line names as they describe what the line is used for.

OK thank you. I wonder why that is not included in the yaml? There is
a description field, I think.

+Rob Herring who may know

Regards,
Simon