On Fri, Dec 06, 2013 at 12:35:10PM +0400, Alexander Shiyan wrote: > > On Fri, Dec 06, 2013 at 12:03:54PM +0400, Alexander Shiyan wrote: > ... > > > > > - fsl,dmacr: DMA Control Register value. This is optional. By default, the > > > > > register is not modified as recommended by the datasheet. > > > > > +- fsl,pwmr: LCDC PWM Contrast Control Register value. That property is > > > > > + optional, but defining it is necessary to get the backlight working. If that > > > > > + property is ommited, the register is zeroed. > > > > > > > > Why isn't this implemented as a backlight driver? Static devicetree > > > > provided values is very limiting. > > > > > > Let's understand the terminology. > > > This register should be renamed according to the datasheet, i.e. LPCCR. > > > As I pointed out earlier, it is NOT control the backlight, this is a contrast control. > > > Yes, it works as PWM, but nothing do with the backlight subsystem. > > > Yes, we can make a driver for this PWM, but how are we going to control it? > > > I misunderstood something? > > > > I stumbled upon 'get the backlight working' which implied for me that it > > should be a backlight driver. But you're right and now I remember we > > talked about this already. > > Hallelujah. > > > I still think this should be something adjustable, not static data. > > Maybe we could change the wording to something like "This property > > provides the default value for the contrast control register" since even > > if we add driver support for controlling the contrast we still want > > to have a sane default. > > Sounds good. > > > BTW the contrast could be controlled with a lcd_device (see > > lcd_device_register) which seems to be very easy to implement. > > Address of register is placed within LCD area, so we cannot use this > memory region, I think is no so easy as you say.... We do not need a separate driver for this. Look for example at drivers/video/bf537-lq035.c, it just calls lcd_device_register() in its probe function. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
