On 05/06/2017 12:38 PM, Ilia Mirkin wrote:
The information comes from the EDID blob supplied by the monitor.
Presumably hwinfo has a primitive EDID parser, which is where that
information comes from. A more complete EDID parser is available at
https://cgit.freedesktop.org/xorg/app/edid-decode/
For example,
$ ./src/edid-decode/edid-decode /sys/class/drm/card0-DVI-D-1/edid
Thanks for you useful reply. That did the trick - I got quite different information than I did with
hwinfo or get-edid but more important - different than what I see in the Xorg.0.log. ( I think
deid-decode is the most complete).
So I'm guessing that nouveau computes the modelines from the combination of what the card and edid
claim they support.
It's quite likely that nouveau doesn't support using YUV outputs
though (which I'm guessing is what the 4:4:4 thing is referring to...
I always get confused by such notation),
Sadly, it is a throw back to 'Chroma subsampling' (my days designing with NTSC editing hardware
still haunt me.) They reduce the color information so there is less bandwidth in the cable. (thus
displayport and thunderbolt3 are headed to 40G (need 18G+overhead or 20G for 12bit 3840x2160 60hz
RGB or only 12G+ for 8bit(24))
only RGB. Also there's no
HDMI 2.0 support in nouveau as yet, mostly due to lack of interest and
hardware. However you should still see a 4k@30 mode exposed
(probably).
HDMI2 does support RGB - see:
http://www.hdmi.org/manufacturer/hdmi_2_0/hdmi_2_0_faq.aspx#146
The main wiki page probably ought to say what subsets of HDMI nouveau supports. Some of the chip
sets from back in the 900 series support hdmi2.0 - so to say nouveau supports that chip sort of
implies that it does hdmi2.0. Anyway - 4k monitors/TVs are getting cheaper and really helpful for
someone coding - soon will be common. I've got another card coming that I can test with.
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