Bug 24305

Summary: Probable race between radeon driver (git) and radeon drm Linux module (drm-next)
Product: xorg Reporter: Diego Elio Pettenò <flameeyes>
Component: Driver/RadeonAssignee: xf86-video-ati maintainers <xorg-driver-ati>
Status: RESOLVED INVALID QA Contact: Xorg Project Team <xorg-team>
Severity: normal    
Priority: medium    
Version: git   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:

Description Diego Elio Pettenò 2009-10-04 10:22:16 UTC
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!).
Comment 1 Adam Jackson 2018-06-12 19:06:38 UTC
Mass closure: This bug has been untouched for more than six years, and is not
obviously still valid. Please reopen this bug or file a new report if you continue to experience issues with current releases.

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