From: Ben Skeggs <bskeggs@redhat.com>
Date: Tue, 5 Oct 2010 06:53:48 +0000 (+1000)
Subject: drm/nouveau: add per-channel mutex, use to lock access to drm's channel
X-Git-Tag: v2.6.38-rc1~419^2~37^2~90
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6a6b73f254123851f7f73ab5e57344a569d6a0ab;p=pandora-kernel.git

drm/nouveau: add per-channel mutex, use to lock access to drm's channel

This fixes a race condition between fbcon acceleration and TTM buffer
moves.  To reproduce:

- start X
- switch to vt and "while (true); do dmesg; done"
- switch to another vt and "sleep 2 && cat /path/to/debugfs/dri/0/evict_vram"
- switch back to vt running dmesg

We don't make use of this on any other channel yet, they're currently
protected by drm_global_mutex.  This will change in the near future.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
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