Re: [PATCH v2] backlight: pwm: reject legacy pwm request for device defined in dt

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Mon, 12 Oct 2015 17:19:35 +0300
Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> wrote:
> 
> > Thierry's patch makes sure that EPROBE_DEFER is not returned when the
> > PWM device definition is not found using in the PWM lookup tables or
> > the DT definition,
> 
> This is okay, but I'm interested in proper handling of cases other than
> EPROBE_DEFER. EPROBE_DEFER and the related issues are on your balance
> and I'm attempting to avoid interfering with it here :)

I keep thinking we should fix all platforms using the ->pwm_id pdata
field to attach a PWM device to a PWM backlight instead of trying to
guess when falling back to the legacy API is acceptable...

> 
> > and in this case the pwm_bl code will fallback to
> > the legacy PWM API, which AFAICT is what you're trying to solve.
> 
> Fallback must happen exclusively under (IS_ERR(pb->pwm) &&
> PTR_ERR(pb->pwm) != -EPROBE_DEFER && !pdev->dev.of_node) condition IMHO.
> 
> Before EPROBE_DEFER appeared on the scene the condition was
> (IS_ERR(pb->pwm) && !pdev->dev.of_node).
> 
> So, the question is if my change requires any updates or not from your
> point of view.

... but from a functional point of view your patch seems correct.

Best Regards,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com