Re: Re: Backlight support

["Antonino A. Daplas" <adaplas@hotpop.com>]

On Thursday 02 December 2004 06:34, Andrew Zabolotny wrote:
> On Tue, 30 Nov 2004 16:28:26 -0000
>
> "Richard Purdie" <rpurdie@rpsys.net> wrote:
> > I think the above patch was nearly there. The issues seemed to be with
> > the method of associating framebuffer devices with their backlights.
> > I've come up with a solution to that problem (see below) so that code
> > can be removed from that patch and that should make it acceptable for
> > mainstream kernel inclusion.
>
> I confirm that the solution you proposed is quite suitable for the job.
> I've already modified the lcd/backlight subsystem, and I have a few
> comments;
>
> a) First of all, the implementation of your idea looks quite well
> (it's simpler and cleaner than the old method), although initially I
> didn't like it (mea culpa). I have removed a lot of now unneeded code
> from b/l support, and also it removes a lot of lcd/backlight
> maintainance code from the framebuffer drivers(pxafb, sa11xxfb,
> mq11xxfb). Last but not least, it removed the class_find_device()
> function that was the sticking point in the discussion with gkh.
>
> b) No modification is needed to the existing lcd/backlight drivers
> (there are about ten of them in hh.org cvs). I've added just one more
> function pointer in the lcd_properties and backlight_properties to a
> function that gets a fb_info and examinates if it is the
> framebuffer to which the lcd/backlight is attached to. If the function
> is NULL, the framebuffer is considered to match (since in PDAs there's
> only one framebuffer, this perfectly fits already existing drivers).
>
> c) There's a problem though; if someone will REALLY want to inspect
> the fb_info, it would be very helpful to be able to deduce somehow the
> 'struct device' associated with the framebuffer, since the fb_info

We already have a struct device field in fb_info. It was initially requested
for swsusp2, but I find that it has other uses as well (in userland).

Tony




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