Red Hat Bugzilla – Bug 196758
nv: DDC fails on laptop LCD, works on external LCD
Last modified: 2007-11-30 17:11:36 EST
Description of problem:
I'm not sure if this should be logged against Xorg-server, or Xorg-drv-nv?
On encountering screen resolution issue, I was advised by Jesse Keating that
using DDC was the preferred option for FC6, so I should comment out
HorizSync/vertRefresh from xorg.conf to force DDC.
Xorg then *does* use correct 1280x1024 resolution on external DVI LCD Sony
XDM-82 *with* DDC, when it failed without it.
Conversely Xorg then *fails* to use 1280x800 resolution on internal Dell WXGA
LCD *with* DDC, but picks good resolution without DDC.
Version-Release number of selected component (if applicable):
Created attachment 131574 [details]
xorg log shows failure to choose correct resolution with DDC on internal LCD
Kindly paste or attach the output of running:
find /proc/acpi/video -type f
I'm hoping nv laptops tend to have EDID blocks in ACPI, in which case I have
code to fix this that should be pretty easy to integrate.
Here is the output for the machine while undocked using onboard LCD panel, do
you need this repeating while it is docked using an external LCD?
[andy@andylaptop ~]$ find /proc/acpi/video -type f
Nah, I'm only interested in the LCD panel info.
What do you get from cat /proc/acpi/video/VID/LCD/EDID ? Real data, or
something like <not supported> ?
(In reply to comment #4)
> What do you get from cat /proc/acpi/video/VID/LCD/EDID ? Real data, or
> something like <not supported> ?
I get <not supported>
Rrgh, that's less cool. Do any of the EDID files give anything else?
$ cat /proc/acpi/video/VID/*/EDID
is this an ACPI BIOS shortcoming?
Yeah, it is.
As of xorg-x11-drv-nv 1.2.0-4, we will notice the native panel size reported by
the BIOS and expand the sync ranges to cover it. So at least we'll get the
native mode size right. There's really no fixing that the machine has no way to
report DDC though.
Please test 1.2.0-4 and reopen this bug if it doesn't work automagically for