XRandR EDID missed with Cedar on LVDS

[Alex Deucher]

On Wed, Nov 2, 2011 at 5:03 PM, Kai-Uwe Behrmann <ku.b at gmx.de> wrote:
> While testing a ATI Cedar equiped laptop I could not get the EDID for the
> interal LVDS in user space. I tried xrandr and xcmddc with no results. But
> the /var/log/Xorg.0.log showed that EDID was detected and hwinfo gives the
> monitor manufacturer. Still user space applications needs the complete data
> block to configure the monitor.

Can you post your xorg log and dmesg output?  There are several possibilities:
1. Your panel does not provide an EDID.  The driver is still able to
determine the native mode timings from tables in the vbios.
2. Your EDID has a bad checksum/etc. and the kernel drm EDID validator
rejects it:
https://bugs.freedesktop.org/show_bug.cgi?id=31943
You can try the patch on that bug and see if it helps.

>
> The driver is Radeon-1.3.0 build from git master 80ba041a .
> Here some more details:
> https://bugzilla.novell.com/show_bug.cgi?id=615740#c21

That bug just looks like a random collection of things vaguely to EDIDs.

Alex