At suspend time on 3.4-rc5 with SNB, we see a i915 register read transaction aborted, presumably as the GT is powered down: WARNING: at drivers/gpu/drm/i915/i915_drv.c:398 gen6_gt_check_fifodbg.isra.6+0x3b/0x50 [i915]() Hardware name: Latitude E5420 MMIO read or write has been dropped ffffffff Modules linked in: brd dm_crypt dm_mod kvm_intel kvm coretemp microcode uvcvideo videobuf2_core videodev videobuf2_vmalloc videobuf2_memops iwlwifi binfmt_misc btrfs i915 cfbcopyarea video cfbimgblt cfbfillrect Pid: 23468, comm: kworker/u:13 Tainted: G W 3.4.0-rc5-debug #10 Call Trace: [<ffffffff8103da3a>] warn_slowpath_common+0x7a/0xb0 [<ffffffff8103db11>] warn_slowpath_fmt+0x41/0x50 [<ffffffffa0020cd5>] ? i915_read32+0x65/0xb0 [i915] [<ffffffffa002055b>] gen6_gt_check_fifodbg.isra.6+0x3b/0x50 [i915] [<ffffffffa00209e9>] __gen6_gt_force_wake_put+0x19/0x20 [i915] [<ffffffffa0020d09>] i915_read32+0x99/0xb0 [i915] [<ffffffffa0024275>] i915_update_gfx_val+0x85/0xe0 [i915] [<ffffffffa0041c4b>] intel_idle_update+0x4b/0xb0 [i915] [<ffffffff81058e96>] process_one_work+0x1b6/0x460 [<ffffffff81058e38>] ? process_one_work+0x158/0x460 [<ffffffffa0041c00>] ? intel_decrease_pllclock+0x130/0x130 [i915] [<ffffffff81059db4>] worker_thread+0x124/0x2d0 [<ffffffff81059c90>] ? manage_workers.isra.25+0x120/0x120 [<ffffffff8105ee3e>] kthread+0x8e/0xa0 [<ffffffff815b6314>] kernel_thread_helper+0x4/0x10 [<ffffffff81069977>] ? finish_task_switch+0x77/0x100 [<ffffffff815b455b>] ? _raw_spin_unlock_irq+0x2b/0x50 [<ffffffff815b49d9>] ? retint_restore_args+0xe/0xe [<ffffffff8105edb0>] ? __init_kthread_worker+0x70/0x70 [<ffffffff815b6310>] ? gs_change+0xb/0xb Thanks, Daniel -- Daniel J Blueman
