On Mon, 2010-12-06 at 13:06 +0800, ext Bryan Wu wrote:

quoted

This kind of backlight is, in a sense, totally separate component from
the panel itself. All they have in common is that they are packaged in
the same physical display module, and they usually share the same
connector.

I have seen three kinds of backlights on OMAP devices:
- on/off GPIO (like on 3430 SDP)

It seems like that we need a gpio_bl.c driver for this kind of usage.

quoted

- PWM based (zoom seems to have this)

I failed to find any PWM or Backlight code in ZOOM boards source file.
Is that possible to us pwm_bl.c driver which is used by pxa?

It's not yet in the official kernel. You can find it in
arch/arm/mach-omap2/board-zoom-display.c in my tree, under devel-branch.

I haven't looked at pwm_bl.c, but I wouldn't be surprised if there
already was a driver we can use for this.

quoted

- Panel controlled (Taal-panel. Also PWM based, but OMAP doesn't see
that)

Yeah, I don't plan to reform this driver at this time.

quoted

The first two could (should?) be totally separate backlights from the
panel itself. For those, a generic backlight driver could perhaps work.
The third one needs to be quite tied to the panel driver, and I'm not
sure how easy it would be to have a separate driver for that.

OK, I totally understand you concern now. How about a GPIO based
backlight driver for the first 2 cases.

GPIO based backlight driver would work properly only for the first case.

 Tomi