Additional info:
reporter:       libreport-2.3.0
WARNING: CPU: 1 PID: 64 at drivers/gpu/drm/drm_irq.c:1121 drm_wait_one_vblank+0x190/0x1a0 [drm]()
vblank not available on crtc 1, ret=-22
Modules linked in: i915 uas usb_storage b44(+) i2c_algo_bit drm_kms_helper drm mii ssb firewire_ohci(+) firewire_core mmc_core ata_generic crc_itu_t pata_acpi yenta_socket video
CPU: 1 PID: 64 Comm: kworker/u4:5 Not tainted 3.19.3-200.fc21.x86_64 #1
Hardware name: Hewlett-Packard HP Compaq nx7400 (RB530UT#ABA)/30A2, BIOS 68YGU Ver. F.0E 08/27/2008
Workqueue: events_unbound async_run_entry_fn
 0000000000000000 000000000ce2c7e3 ffff88003689b768 ffffffff8176e215
 0000000000000000 ffff88003689b7c0 ffff88003689b7a8 ffffffff8109bc1a
 0000000000000007 ffff880035f90000 ffff880035d60000 0000000000000001
Call Trace:
 [<ffffffff8176e215>] dump_stack+0x45/0x57
 [<ffffffff8109bc1a>] warn_slowpath_common+0x8a/0xc0
 [<ffffffff8109bca5>] warn_slowpath_fmt+0x55/0x70
 [<ffffffffa009e930>] drm_wait_one_vblank+0x190/0x1a0 [drm]
 [<ffffffffa018084f>] ? gen4_read32+0x4f/0xc0 [i915]
 [<ffffffffa01d4b95>] intel_enable_tv+0x25/0x60 [i915]
 [<ffffffffa019dc4b>] i9xx_crtc_enable+0x3fb/0x4c0 [i915]
 [<ffffffffa019c1c2>] __intel_set_mode+0x8a2/0xca0 [i915]
 [<ffffffffa01a236c>] intel_set_mode+0x7c/0xc0 [i915]
 [<ffffffffa018d26c>] ? intel_framebuffer_init+0x31c/0x440 [i915]
 [<ffffffffa01a2636>] intel_get_load_detect_pipe+0x286/0x620 [i915]
 [<ffffffffa01d5794>] intel_tv_detect+0x134/0x5d0 [i915]
 [<ffffffff813a7c70>] ? merge+0x60/0xb0
 [<ffffffffa00fec03>] drm_helper_probe_single_connector_modes_merge_bits+0x303/0x460 [drm_kms_helper]
 [<ffffffffa00fed73>] drm_helper_probe_single_connector_modes+0x13/0x20 [drm_kms_helper]
 [<ffffffffa0108bb0>] drm_fb_helper_probe_connector_modes.isra.3+0x50/0x70 [drm_kms_helper]
 [<ffffffffa0109fdc>] drm_fb_helper_initial_config+0x5c/0x3d0 [drm_kms_helper]
 [<ffffffff81013610>] ? __switch_to+0x150/0x5e0
 [<ffffffffa01b1fdb>] intel_fbdev_initial_config+0x1b/0x20 [i915]
 [<ffffffff810bd06a>] async_run_entry_fn+0x4a/0x150
 [<ffffffff810b487c>] process_one_work+0x14c/0x3f0
 [<ffffffff810b52f3>] worker_thread+0x53/0x470
 [<ffffffff810b52a0>] ? rescuer_thread+0x300/0x300
 [<ffffffff810ba548>] kthread+0xd8/0xf0
 [<ffffffff810ba470>] ? kthread_create_on_node+0x1b0/0x1b0
 [<ffffffff81774958>] ret_from_fork+0x58/0x90
 [<ffffffff810ba470>] ? kthread_create_on_node+0x1b0/0x1b0

Potential duplicate: bug 1210101