[PATCH 2/6] led-uclass: honour ->label field populated by driver's own .bind

[Christian Gmeiner]

ping

Am Mo., 23. Okt. 2023 um 12:45 Uhr schrieb Marek Vasut <marex at denx.de>:
>
> On 10/23/23 10:51, Rasmus Villemoes wrote:
> > On 19/10/2023 15.54, Marek Vasut wrote:
> >> On 10/19/23 11:58, Rasmus Villemoes wrote:
> >>> If the driver's own .bind method has populated uc_plat->label, don't
> >>> override that. This is necessary for an upcoming driver for ti,lp5562,
> >>> where the DT binding unfortunately says to use "chan-name" and not
> >>> "label".
> >>>
> >>> Signed-off-by: Rasmus Villemoes <rasmus.villemoes at prevas.dk>
> >>> ---
> >>>    drivers/led/led-uclass.c | 4 +++-
> >>>    1 file changed, 3 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/led/led-uclass.c b/drivers/led/led-uclass.c
> >>> index 5a5d07b9a7..0232fa84de 100644
> >>> --- a/drivers/led/led-uclass.c
> >>> +++ b/drivers/led/led-uclass.c
> >>> @@ -71,7 +71,9 @@ static int led_post_bind(struct udevice *dev)
> >>>        struct led_uc_plat *uc_plat = dev_get_uclass_plat(dev);
> >>>        const char *default_state;
> >>>    -    uc_plat->label = dev_read_string(dev, "label");
> >>> +    if (!uc_plat->label)
> >>> +        uc_plat->label = dev_read_string(dev, "label");
> >>> +
> >>
> >> One thing I have to wonder about is, why does this controller have label
> >> property in the top-level node , what is that used for ?
> >>
> >> (see Linux Documentation/devicetree/bindings/leds/leds-lp55xx.yaml)
> >>
> >> Reviewed-by: Marek Vasut <marex at denx.de>
> >
> > Reading the linux driver, it seems that the top-level label, if any, is
> > used as part of the naming for individual channels if they don't have
> > individual chan-name properties:
> >
> >
> >          if (pdata->led_config[chan].name) {
> >                  led->cdev.name = pdata->led_config[chan].name;
> >          } else {
> >                  snprintf(name, sizeof(name), "%s:channel%d",
> >                          pdata->label ? : chip->cl->name, chan);
> >                  led->cdev.name = name;
> >          }
> >
> > but I think the rationale in d1188adb2dabc is a bit weak, since the only
> > example also does have individual chan-name properties.
> >
> > [Complete aside: At first I thought it was related to the multi-color
> > LED work that has been ongoing for many many years (I think there was an
> > LWN article at some point), where this could be exposed as a single
> > multi-color LED, as opposed to the "traditional" three/four individual
> > LEDs. In the former case, there would only be one sysfs entry, but with
> > attributes exposing the multicolor functionality. I must admit I don't
> > know the status of that work, when something reaches v31,
> > http://archive.lwn.net:8080/linux-kernel/20200722071055.GA8984@amd/t/ ,
> > it's hard to know if it ever lands, or if pieces of it has landed.]
>
> +CC Pavel



-- 
greets
--
Christian Gmeiner, MSc

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