[Bug 29726] New: New CRTC ID query breaks Radeon DRM in Zaphod mode

[bugzilla-daemon@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=29726

           Summary: New CRTC ID query breaks Radeon DRM in Zaphod mode
           Product: DRI
           Version: unspecified
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Radeon
        AssignedTo: dri-devel@lists.freedesktop.org
        ReportedBy: chewi@aura-online.co.uk


Created an attachment (id=38044)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=38044)
Patch against 2.6.35.3 to remove the offending code

Since upgrading from 2.6.34, programs such as Neverball and MythTV have only
updated the screen while moving the mouse or pressing keys. I managed to bisect
the kernel back to the infamous commit
bc35afdb182d4c48c889fe27ba7a5d7ea0c8194d, along with its related fix
0baf2d8fe43fdd81faa30e65ff71785c99c78520. These add support for querying the
hardware CRTC ID. I knew straight away that this was probably related to me
using Zaphod mode and a test with a single screen did indeed make the problem
go away. There was still the occasional flicker though, which may or may not be
related. I don't get any flickering with the code removed (see attached patch)
while using Zaphod mode.

I knew it was probably related to Zaphod mode because I know that the CRTCs
play a key role there but beyond that, I'm not sure what the problem is. I
don't know exactly what this code is used for.

I probably should have tested two screens without Zaphod mode but my wife will
kill me if I restart the machine again. ;) I'm guessing that isn't affected
because it's a very common setup.

-- 
Configure bugmail: https://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.