TV output properties

Jesse Barnes jbarnes at
Sat Nov 10 10:07:31 PST 2007

On Friday, November 09, 2007 10:29 pm Keith Packard wrote:
> On Fri, 2007-11-09 at 12:20 -0800, Jesse Barnes wrote:
> > Since seems to be down, I'm sending these patches
> > out for testing to the list.
> >
> > They add hue, saturation, contrast and brightness properties to the TV
> > output and set default values that will hopefully work for people.  In
> > order to use the new properties though, you'll need the attached patch to
> > xrandr to properly display and set 8 bit integer values.
> >
> > Please test it out and let me know if it works for you.
> >
> > How to expose the various properties is still up in the air, right now
> > they're just exposed as 8 bit values, since that's what goes into the
> > actual color knob register, but they could be exposed in a friendlier way
> > (e.g. hue as 0-360 degrees value, saturation and contrast as 2.6 fixed
> > point values), though that probably wouldn't make much difference to the
> > user experience. Any opinions?  Is that best left to fancy GUI
> > applications?
> Any reason not to expose these as 32-bit values instead? We support
> range limited 32-bit values, and this might reduce compatibility issues
> with hardware that needs more bits.

No, we could definitely expose them as larger values.  In fact, the output 
properties we have now (LVDS backlight & TV stuff) should probably be 
generic.  That way they'd be named the same across different types of chips, 
which would make client application development easier.  And the drivers 
could just implement simple callback code to get and set the values, rather 
than having a bunch of RandR & Atom boilerplate...

Maybe the radeon, via, or nouveau guys could chime in here so we could come up 
with a decent subset.


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