[RFC/PATCH 0/2] Backlight support

[Sascha Hauer]

On Fri, Oct 07, 2011 at 10:47:34PM +0200, Gregory CLEMENT wrote:
> On 10/07/2011 03:15 PM, Sascha Hauer wrote:
> > Hi Gregory,
> > 
> Hi Sasha,
> 
> thanks to have taken some time to have a look on my series.
> 
> > On Thu, Oct 06, 2011 at 10:05:07AM +0200, Gregory CLEMENT wrote:
> >> This patch set is a RFC about a backlight framework. The purpose of
> >> this framework is mainly to allow to add easily a support for a
> >> backlight with the possibility of setting brightness directly from the
> >> barebox shell using the brightness parameter.
> >>
> >> An implementation is provided for i.MX23 by using the PWM. It was
> >> tested on a custom i.MX23 base board.
> > 
> > Two things that bother me in this series.
> > 
> > First thing is that I wonder if it would be better to not
> > register a seperate device for backlight. How about a call
> > like this:
> > 
> > fb_register_backlight(const char *fb,
> > 	void (*set_brightness)(int brightness, void *priv));
> > 
> > The core would only need a function to find the struct device_d
> > by the corresponding "fbx" string. This way we could add the
> > brightness variable to the framebuffer and not a seperate device,
> > so fb0.brightness=50.
> > 
> 
> I wasn't entirely convinced by having a driver with a single
> function. I came to this by several iterations and it didn't lead me
> in the best direction. That's why I called this series a RFC. I will
> take in account your idea and propose a new version.
> 
> > The second thing is that the pwm you use for the mxs backlight
> > is a generic pwm which not necessarily drives a backlight. We
> > should have a generic pwm api for this. Otherwise we end up
> > with different drivers for the same pwm.
> 
> As I didn't see any pwm framework or API I wasn't sure it was planned
> or needed to have it in barebox. But I volunteer to work on it. So how
> do you see it: as an API or as complete driver ?

Maybe you can use https://lkml.org/lkml/2011/6/30/163 as a template.
It should be easy to convert to barebox and also gives us the chance
that we can easily adopt drivers from the kernel.

Sascha

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