Created attachment 118445 [details]
/sys/class/drm/card0/error following crash on Ubuntu 14.04

Reproducible: yes

Summary: playing https://www.youtube.com/watch?v=mY9x0AHUa-E in Firefox 41.0 or Chromium 45.0.2454.85, a second or two of video plays, then GPU crashes (and browser crash if Firefox); mouse pointer is fixed in position but can change shape until reboot.  Ctrl+Alt+Fn won't display other virtual console.  (Also occurs on other HTML5 YouTube video, but less reliably.)  

Sep 25 10:45:26 PC-2 kernel: [  397.000093] [drm] stuck on render ring
Sep 25 10:45:26 PC-2 kernel: [  397.000101] [drm] GPU crash dump saved to /sys/class/drm/card0/error
Sep 25 10:45:26 PC-2 kernel: [  397.000104] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
Sep 25 10:45:26 PC-2 kernel: [  397.000106] [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
Sep 25 10:45:26 PC-2 kernel: [  397.000108] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
Sep 25 10:45:26 PC-2 kernel: [  397.000111] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
Sep 25 10:45:26 PC-2 kernel: [  397.000984] [drm:i915_set_reset_status] *ERROR* render ring hung inside bo (0x48ab000 ctx 0) at 0x48ab708
Sep 25 10:45:26 PC-2 kernel: [  397.072060] [drm] GMBUS [i915 gmbus vga] timed out, falling back to bit banging on pin 2
Sep 25 10:45:27 PC-2 kernel: [  397.508017] [drm:i915_reset] *ERROR* Failed to reset chip.
Sep 25 10:45:27 PC-2 kernel: [  397.870517] Chrome_ChildThr[2998]: segfault at 0 ip b76da11e sp b1bfea00 error 6 in plugin-container[b76d3000+3f000]

Sep 25 10:47:19 PC-2 kernel: [  509.880363] WARNING: CPU: 1 PID: 1960 at /build/linux-zqVCY7/linux-3.13.0/drivers/gpu/drm/i915/intel_display.c:922 assert_pll+0x73/0x80 [i915]()
Sep 25 10:47:19 PC-2 kernel: [  509.880364] PLL state assertion failure (expected on, current off)
Sep 25 10:47:19 PC-2 kernel: [  509.880387] Modules linked in: snd_hrtimer pci_stub vboxpci(OX) vboxnetadp(OX) vboxnetflt(OX) vboxdrv(OX) cuse dm_crypt bnep rfcomm bluetooth gpio_ich hp_wmi sparse_keymap snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer coretemp kvm serio_raw lpc_ich shpchp snd soundcore parport_pc mac_hid binfmt_misc ppdev lp parport raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq raid1 raid0 multipath linear hid_generic usbhid hid i915 i2c_algo_bit floppy drm_kms_helper drm video pata_acpi e1000e wmi psmouse ptp pps_core

Youtube video characteristics:
Video ID: mY9x0AHUa-E
Dimensions: 854 x 480
Resolution: 640 x 360
Volume: 100%
Stream Type: https
CPN:jZE_mQvy-9ca8qqq
Mime Type: video/mp4; codecs="avc1.42001E, mp4a.40.2"
DASH: no (18)

Linux 3.13.0-63-generic #103-Ubuntu SMP Fri Aug 14 21:43:30 UTC 2015 i686
Ubuntu 14.04.3 LTS
xserver-xorg-video-intel:i386/trusty-updates 2:2.99.910-0ubuntu1.6 uptodate
intel-gpu-tools:i386/trusty-updates 1.3-0ubuntu2.1 uptodate
libdrm-intel1:i386/trusty-updates 2.4.60-2~ubuntu14.04.1 uptodate
libegl1-mesa:i386/trusty-updates 10.1.3-0ubuntu0.4 uptodate
libegl1-mesa-drivers:i386/trusty-updates 10.1.3-0ubuntu0.4 uptodate
libgl1-mesa-dev:i386/trusty-updates 10.1.3-0ubuntu0.4 uptodate
libgl1-mesa-dri:i386/trusty-updates 10.1.3-0ubuntu0.4 uptodate
libgl1-mesa-glx:i386/trusty-updates 10.1.3-0ubuntu0.4 uptodate

00:00.0 Host bridge: Intel Corporation 82Q963/Q965 Memory Controller Hub (rev 02)
00:02.0 VGA compatible controller: Intel Corporation 82Q963/Q965 Integrated Graphics Controller (rev 02) (prog-if 00 [VGA controller])
        Subsystem: Hewlett-Packard Company Device 2801
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-

       description: VGA compatible controller
       product: 82Q963/Q965 Integrated Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 02
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:41 memory:f0400000-f04fffff memory:e0000000-efffffff ioport:1100(size=8)

Possibly related: bug 89263, bug 89990, bug 77918, bug 91254