linux-kernel - Re: [PATCH] leds: pwm: set polarity on non DT platforms

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Date:	Wed, 19 Mar 2014 00:09:46 +0100
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Bryan Wu <cooloney@...il.com>
Cc:	Thierry Reding <thierry.reding@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Linux LED Subsystem <linux-leds@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] leds: pwm: set polarity on non DT platforms

On 18/03/2014 at 16:02:51 -0700, Bryan Wu wrote :
> On Mon, Mar 17, 2014 at 11:38 AM, Alexandre Belloni
> <alexandre.belloni@...e-electrons.com> wrote:
> > Set inversed polarity when .active_low is set in the platform_data. With device
> > tree, this is taken care of by of_pwm_xlate_with_flags(), called from
> > of_pwm_get().
> >
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> > ---
> >  drivers/leds/leds-pwm.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
> > index 605047428b5a..09681556a6aa 100644
> > --- a/drivers/leds/leds-pwm.c
> > +++ b/drivers/leds/leds-pwm.c
> > @@ -180,6 +180,11 @@ static int led_pwm_probe(struct platform_device *pdev)
> >                         led_dat->cdev.max_brightness = cur_led->max_brightness;
> >                         led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
> >
> > +                       if (led_dat->active_low)
> 
> Why .active_low needs to inverse PWM polarity? In
> of_pwm_xlate_with_flags(), it checked with PWM_POLARITY_INVERSED in
> args. Moreover in of_pwm_simple_xlate() and pxa_pwm_of_xlate(), we
> didn't inverse PWM polarity at all.
> 

Yeah, exactly, there is no issue when using device tree. What I'm trying
to fix here is th non-DT case where of_pwm_xlate_with_flags() is not
called.

> Add Thierry to review this.
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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