About "Automatic" for "Broadcast RGB" in i915

[Tom Yan]

http://lists.freedesktop.org/archives/dri-devel/2013-January/033572.html

Dear All,

Please, never do pointless stuff like that.

I don't know what exactly are written in the "CEA guidelines"
mentioned in the above posts (AFAIK one cannot get a copy of them for
free legally), but no one should follow some "guidelines" like that
when it make zero sense.

Unlike colorspace, literally it's impossible to detect what RGB ranges
can a monitor takes, so having an "Automatic" mechanism for it is very
likely to be insane. Worsestill, using modes to determine the range is
absurd.

What does that imply? It implies within a same product line of
monitors, models with different physical size (which is likely to have
different optimal resolutions) should use different rgb ranges, and
the range should also varies when we switch resolution ourselves.

The only reason I can think of for those guidelines to exists is, it
makes consumer products send limited range signal when it's likely
video playback (coz that's how most video is stored), and full range
for other usage (such as gameplay). But this mechanism could hardly
apply to PC.

IMO keeping Full as a default and allow Limited as an option is the
only sane way for PC, especially when better HDTV nowadays is starting
to accept full RGB range signal. But if you guys think that, people
with some cheaper HDTV or some awkward PC monitors which doesn't even
do what's aka "PC Level" should get more care, just make Limited as
default then.

But please, don't deceive users with some fake Automatic option/fix
like that. It sucks.

Regards,
Tom Yan

P.S. I am not a programmer or tech expert here, if there's anything
wrong in this mail, I'm glad that you point it out to me.