Seems to have been introduced by a change between 3.7-rc1 and 3.7-rc2
(ddffeb8c4d0331..6f0c0580b7). Don't have time to track that further now.
Maybe it doesn't have to do with suspend/resume directly, but is caused by it
as some sort of side-effect?

The following commits fall within that range (only one specific to cayman), I
guess I can skip some of them:

bd6126b - drm: radeon: fix printk format warning (vor 4 Monaten)
8ad33cd - drm/radeon: fix spelling typos in debugging output
0829184 - drm/radeon: Don't destroy I2C Bus Rec in
radeon_ext_tmds_enc_destroy().
3691fee - drm/radeon: check if pcie gen 2 is already enabled (v2)
c1a7ca0 - drm/radeon/cayman: set VM max pfn at MC init
13e55c3 - drm/radeon: separate pt alloc from lru add
d72d43c - drm/radeon: don't add the IB pool to all VMs v2
90a51a3 - drm/radeon: allocate page tables on demand v4
23d4f1f - drm/radeon: update comments to clarify VM setup (v2)
29dbe3b - drm/radeon: allocate PPLLs from low to high
cd23492 - drm/radeon: fix compilation with backlight disabled<Alex Deucher>
a187193 - drm/radeon: use %zu for formatting size_t