[PATCHv6 0/3] pwm: imx: support output polarity inversion

[Alexandre Belloni]

On 09/09/2016 at 09:18:57 +0200, Lothar Waßmann wrote :
> Hi,
> 
> On Thu, 08 Sep 2016 15:15:57 -0700 Stefan Agner wrote:
> > On 2014-10-10 07:22, Lothar Waßmann wrote:
> > > This patch series adds support for polarity inversion to the pwm-imx
> > > driver. The patches have been tested on i.MX6, i.MX53 and with the
> > > ti-ehrpwm.c driver.
> > 
> > Do you know what prevented this patchset from getting merged?
> > 
> No idea.
> 
> > We are looking for Polarity support in PWM for too, this is especially
> > useful for backlight control.
> > 
> Actually the PWM driver may be the wrong place to achieve this. When
> the backlight driver sets the brightness to 0 to switch the backlight
> off, it will disable the PWM. This will make the PWM pin go LOW and
> thus turn the backlight to full brightness rather than off (unless there
> is an additional GPIO that controls a backlight enable pin on the LCD).
> 

Isn't a properly designed PWM putting a high level on its pin when
disabled and configured with inversed polarity ?
If the HW is capable of it, the driver should be fixed.


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