[PATCH 2/2] video: imxfb: Add feature to setup PWM Contrast Control Register

[Alexander Shiyan]

On Thu, 25 Jul 2013 15:38:56 +0200
Markus Pargmann <mpa at pengutronix.de> wrote:

> Hi,
> 
> On Sun, Jul 21, 2013 at 12:35:09PM +0400, Alexander Shiyan wrote:
> > This patch adds feature to setup PWM Contrast Control Register.
> > This register is used to control the signal output at the contrast pin,
> > which controls contrast of the LCD panel.
> 
> http://www.spinics.net/lists/linux-fbdev/msg10002.html

PWM? I can not understand how the PWM driver will be connected to the
framebuffer driver. It is not backlight, this is contrast.
Even if we imagine that the driver will be connected through phandle,
then we will need to have at least 4! additional parameters in the framebuffer
driver: freq source, frequency and active pulse period + phandle to PWM.
Is it worth it, given that these parameters should not be adjustable?
On my opinion, the only one additional parameter in framebuffer is enough.
Thanks.

[...]
> > ---
> >  Documentation/devicetree/bindings/video/fsl,imx-fb.txt | 1 +
> >  drivers/video/imxfb.c                                  | 2 +-
> >  2 files changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/video/fsl,imx-fb.txt b/Documentation/devicetree/bindings/video/fsl,imx-fb.txt
> > index 46da08d..be10c65 100644
> > --- a/Documentation/devicetree/bindings/video/fsl,imx-fb.txt
> > +++ b/Documentation/devicetree/bindings/video/fsl,imx-fb.txt
> > @@ -18,6 +18,7 @@ Optional properties:
> >  - fsl,dmacr: DMA Control Register value. This is optional. By default, the
> >  	register is not modified as recommended by the datasheet.
> >  - fsl,lscr1: LCDC Sharp Configuration Register value.
> > +- fsl,pwmr: LCDC PWM Contrast Control Register value.
> >  
> >  Example:
> >  
> > diff --git a/drivers/video/imxfb.c b/drivers/video/imxfb.c
> > index 8e104c4..d98299a 100644
> > --- a/drivers/video/imxfb.c
> > +++ b/drivers/video/imxfb.c
> > @@ -806,8 +806,8 @@ static int imxfb_init_fbinfo(struct platform_device *pdev,
> >  
> >  		fbi->lscr1 = IMXFB_LSCR1_DEFAULT;
> >  		of_property_read_u32(np, "fsl,lscr1", &fbi->lscr1);
> > -
> >  		of_property_read_u32(np, "fsl,dmacr", &fbi->dmacr);
> > +		of_property_read_u32(np, "fsl,pwmr", &fbi->pwmr);
> >  
> >  		/* These two function pointers could be used by some specific
> >  		 * platforms. */
> > -- 

-- 
Alexander Shiyan <shc_work at mail.ru>