i915 kernel warning

[Mihai Donțu]

Hi,

This just happened to me:

Aug  6 21:37:37 mdontu-l kernel: ------------[ cut here ]------------
Aug  6 21:37:37 mdontu-l kernel: WARNING: CPU: 3 PID: 4823 at drivers/gpu/drm/i915/intel_display.c:3313 intel_crtc_wait_for_pending_flips+0x16c/0x180()
Aug  6 21:37:37 mdontu-l kernel: Modules linked in: hdaps(O) tp_smapi(O) thinkpad_ec(O) vboxnetadp(O) vboxnetflt(O) vboxdrv(O) iwldvm iwlwifi e1000e
Aug  6 21:37:37 mdontu-l kernel: CPU: 3 PID: 4823 Comm: X Tainted: G           O  3.16.0-gentoo #2
Aug  6 21:37:37 mdontu-l kernel: Hardware name: LENOVO 4178A4G/4178A4G, BIOS 83ET76WW (1.46 ) 07/05/2013
Aug  6 21:37:37 mdontu-l kernel:  0000000000000009 ffff88041d63fbf8 ffffffff93c212a4 0000000000000000
Aug  6 21:37:37 mdontu-l kernel:  ffff88041d63fc30 ffffffff930e3a2d 0000000000000000 ffff880427b7c000
Aug  6 21:37:37 mdontu-l kernel:  ffff880426f380a8 ffff880426ddf800 ffff880426ddf800 ffff88041d63fc40
Aug  6 21:37:37 mdontu-l kernel: Call Trace:
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff93c212a4>] dump_stack+0x45/0x56
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff930e3a2d>] warn_slowpath_common+0x7d/0xa0
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff930e3b0a>] warn_slowpath_null+0x1a/0x20
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff936994dc>] intel_crtc_wait_for_pending_flips+0x16c/0x180
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff931240f0>] ? __wake_up_sync+0x20/0x20
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9369c753>] intel_crtc_disable_planes+0x33/0x1c0
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9369cd20>] ironlake_crtc_disable+0x50/0x970
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff936457bf>] ? drm_modeset_lock+0x2f/0xd0
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff93c27fe2>] ? mutex_lock+0x12/0x30
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9369e0af>] intel_crtc_update_dpms+0x6f/0xa0
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff936a1f09>] intel_connector_dpms+0x59/0x70
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9363c8c9>] drm_mode_obj_set_property_ioctl+0x399/0x3a0
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9363c900>] drm_mode_connector_property_set_ioctl+0x30/0x40
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9362b83f>] drm_ioctl+0x1df/0x680
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff935cf8dc>] ? backlight_generate_event+0x5c/0x80
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff935d0021>] ? brightness_store+0x91/0xd0
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff93244a0c>] ? fsnotify+0x27c/0x350
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9321b498>] do_vfs_ioctl+0x2c8/0x490
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9320b911>] ? __sb_end_write+0x31/0x60
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff93209512>] ? vfs_write+0x1c2/0x200
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff9321b6a1>] SyS_ioctl+0x41/0x80
Aug  6 21:37:37 mdontu-l kernel:  [<ffffffff93c29b52>] system_call_fastpath+0x16/0x1b
Aug  6 21:37:37 mdontu-l kernel: ---[ end trace 131b19886670715a ]---

X appeared to have stopped rendering (or nothing goes through), but the
applications worked fine (I still had sound from a video). My video
card is:

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
        Subsystem: Lenovo Device 21d0
        Flags: bus master, fast devsel, latency 0, IRQ 43
        Memory at f1400000 (64-bit, non-prefetchable) [size=4M]
        Memory at e0000000 (64-bit, prefetchable) [size=256M]
        I/O ports at 6000 [size=64]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: [d0] Power Management version 2
        Capabilities: [a4] PCI Advanced Features
        Kernel driver in use: i915

I was able to switch to the terminal and reboot.

I suspect this is new in 3.16 and I've noticed some other oddities
since I upgraded from 3.15.8:
 * when adjusting the screen brightness, the minimum setting is now
   "LCD off";
 * when watching a video in fullscreen, I can see a flicker every 10s
   or so.

Thanks,

-- 
Mihai Donțu