[Bug 24305] New: Probable race between radeon driver (git) and radeon drm Linux module (drm-next)

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=24305

           Summary: Probable race between radeon driver (git) and radeon drm
                    Linux module (drm-next)
           Product: xorg
           Version: git
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/Radeon
        AssignedTo: xorg-driver-ati at lists.x.org
        ReportedBy: flameeyes at gmail.com
         QAContact: xorg-team at lists.x.org


I've notice this last night after fighting with this a bit, since I couldn't
get anything on the monitor.

There seems to be a race between the loading of the radeon drm module, and the
check for KMS support in the radeon driver in the X process. The radeon driver
looks for the /sys/bus/pci/devices/$path/drm/controlD* directory (controlD64 on
my system) to make sure that KMS mode report is supported; unfortunately it
seems like this check happens before the directory is actually created. Loading
the module _before_ starting X, or building the radeon drm inside the kernel
itself solves the problem since the controlD directory is created before X is
started.

There is another related problem: when the controlD directory is not found, KMS
is not detected and dri1 is initialized (which will also fail because the
kernel is running dri2); somehow this leaves the card in an inconsistent state,
and when X is started again afterwards (and KMS is detected), X blocks into
calling ioctl (which repeatedly returns -EBUSY). This happens with xorg-server
1.6.3.901, 1.6.4 and 1.7.0.

HTH,
Diego

P.S.: sorry but I'm afraid I don't have a failure dmesg and Xorg.0.log :( I was
debugging this last night around 4am so I didn't have the idea of saving them
for later reporting… if I need to I can look into providing them.

P.P.S.: while I had radeon drm built as a module rather than bult-in it kernel
paniced on rmmod… of that, too, I forgot to save the log :/ but I'll try to
reproduce that next week as well, and save the log (serial console ftw!).


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