inexplicable fallback mode used when preferred mode 2560x1080 not supported by connection
mrmazda at earthlink.net
Sun Feb 12 10:10:32 UTC 2017
Since acquiring my 2560x1080 U2913WM Dell for use among several multiboot PCs,
with AMD/ATI, Intel and NVidia gfxchips represented, I'm frequently annoyed by
lack of support for native mode by the cable actually connected, not so much by
the lack of support itself as by the mode fallen back to. In most cases, the
fallback selected is either 1400x1050 at 75 or 1152x864 at 75, while if using a VGA
connection, 2560x1080 is supported for every PC and gfxchip I've tried so far.
Xorg.0.log plus output from inxi -c0 -G, hwinfo --gfxcard and xrandr from a
GT210 on host big31 booted to openSUSE Tumbleweed and modesetting driver,
which falls to 1400x1050 using an HDMI cable. Using instead nouveau, fall is to
1152x864, same as same PC booted to openSUSE 42.1 using HDMI and modesetting
driver, and same PC booted to Fedora 25 using HDMI and nouveau driver.
Obviously the display isn't likely capable of any less than 1920x1080 via HDMI,
because Intel gfx host big41 booted to Debian does it:
OTOH, this installation when I try to use xrandr in startup script to get
2560x1080 via HDMI also produces instead 1152x864. :-(
Why isn't the fallback only to 1920x1080 instead of all the way back to a much
less appropriate and anachronistic 4:3 mode? How can I determine whether the
fault is driver(s), Xorg, Display or Gfxchip? Is an Xorg bug filing at
freedesktop.org indicated here? Could more elaborate xrandr on startup or
xorg.conf produce 1920x1080 in these cases?
"The wise are known for their understanding, and pleasant
words are persuasive." Proverbs 16:21 (New Living Translation)
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