Re: [PATCH v6 2/2] leds: lm3601x: Introduce the lm3601x LED driver

[Jacek Anaszewski]

Dan,

On 05/17/2018 04:34 PM, Dan Murphy wrote:
> Jacek
>
> On 05/16/2018 04:17 PM, Dan Murphy wrote:
> <snip>
>
> > > > > > > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ if (!ret)
> > > > > > >
> > > > > > > if (ret) sounds more natural. And better just to split
> > > > > > >
> > > > > > > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ snprintf(led->led_name, sizeof(led->led_name),
> > > > > > > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ "%s:%s", led->led_node->name, name);
> > > > > > > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ else
> > > > > > > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ snprintf(led->led_name, sizeof(led->led_name),
> > > > > > > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ "%s:torch", led->led_node->name);
> > > > > > >
> > > > > > > const char *tmp;
> > > > > > >
> > > > > > > ret = device_property_read_...(&tmp);
> > > > > > > if (ret)
> > > > > > >  Â tmp = ...
> > > > > > > sprintf(...);
> > > >
> > > > We're no longer taking devicename section of a LED class device name
> > > > from DT, so it will look differently anyway.
>
> So in adding the device_property code I think we again are reaching the LED label issue.
> In ARM with DT we would take the parent device node name and append it to the label

AFAIR this approach (parent DT node name used for devicename ) was 
incidentally applied in leds-as3645a.c. Soon after that we started
to use led-controller for parent DT name, according to Rob's request.

In the most of LED class drivers this is a child DT node which is used
for devicename, in case label is absent.

> if the optional label property was not available.  In migrating to the device_property
> APIs we don't or can't depend on that parent node anymore.
>
> So for the case where the label property does not exist should we use a hard coded name
> or should we try to use the name from a device_id table.
>
> This is how we did this for the leds-lp8860 driver.  If the label did not exist we used the
> i2c_device_id table and pulled the string from there.

i2c_device_id can't be applied as a generic pattern, but only for I2C
hooked devices. Nonetheless since it allows to save few lines of code
in case of drivers supporting a family of chips we can use it.

We are going to get rid of a devicename section from LED class device
name soon anyway, since it is redundant.

--
Best regards,
Jacek Anaszewski