[Intel-gfx] I've got the RC6 bug

[Daniel Vetter]

On Mon, Jan 16, 2012 at 05:18:17PM +0100, CC wrote:
> Hi,
> 
> I've heard that you need users having the RC6 bug.
> 
> I have the following setup:
> CPU: Intel Core i5-2500K
> Mainboard: ASRock Z68 Pro3-M
> Memory: Corsair Vengeance CMZ8GX3M2A1866C9
> 
> Although the CPU doesn't support VT-d, I disabled all virtualization
> support in the UEFI setup.
> 
> I use Arch Linux and Gnome 3 in the fallback mode. The problem is more
> drastic without fallback mode, however.
> 
> Whenever I enable RC6, I get the a few of these errors in dmesg:
> 
> [   48.900000] WARNING: at drivers/gpu/drm/i915/i915_drv.c:387
> __gen6_gt_wait_for_fifo+0x94/0xa0 [i915]()
> [   48.900002] Hardware name: To Be Filled By O.E.M.
> [   48.900002] Modules linked in: ipv6 fuse ext2 snd_hda_codec_hdmi
> snd_hda_codec_realtek mei(C) joydev r8169 shpchp pci_hotplug usbhid hid
> snd_hda_intel iTCO_wdt mii iTCO_vendor_support i2c_i801 snd_hda_codec
> processor snd_hwdep snd_pcm snd_timer snd soundcore snd_page_alloc psmouse
> serio_raw pcspkr evdev ext4 mbcache jbd2 crc16 xhci_hcd ehci_hcd usbcore
> i915 drm_kms_helper drm intel_agp i2c_algo_bit button intel_gtt i2c_core
> video sd_mod ahci libahci libata scsi_mod
> [   48.900019] Pid: 623, comm: Xorg Tainted: G        WC  3.1.9-2-ARCH #1
> [   48.900020] Call Trace:
> [   48.900023]  [<ffffffff81061bef>] warn_slowpath_common+0x7f/0xc0
> [   48.900025]  [<ffffffff81061c4a>] warn_slowpath_null+0x1a/0x20
> [   48.900028]  [<ffffffffa00e0764>] __gen6_gt_wait_for_fifo+0x94/0xa0
> [i915]
> [   48.900032]  [<ffffffffa015d2d5>] ring_write_tail+0x65/0x120 [i915]
> [   48.900036]  [<ffffffffa01619bc>] render_ring_flush+0xbc/0xe0 [i915]
> [   48.900040]  [<ffffffffa010b803>] i915_gem_flush_ring+0x43/0x250 [i915]
> [   48.900044]  [<ffffffffa0112b50>]
> i915_gem_do_execbuffer.isra.7+0x1020/0x16d0 [i915]
> [   48.900048]  [<ffffffffa01136bb>] i915_gem_execbuffer2+0x8b/0x240 [i915]
> [   48.900051]  [<ffffffffa0098434>] drm_ioctl+0x3e4/0x4c0 [drm]
> [   48.900053]  [<ffffffff810746cb>] ? recalc_sigpending+0x1b/0x50
> [   48.900057]  [<ffffffffa0113630>] ? i915_gem_execbuffer+0x430/0x430
> [i915]
> [   48.900059]  [<ffffffff8101e9b1>] ? fpu_finit+0x21/0x40
> [   48.900061]  [<ffffffff8116fddf>] do_vfs_ioctl+0x8f/0x500
> [   48.900063]  [<ffffffff81014beb>] ? sys_rt_sigreturn+0x1eb/0x200
> [   48.900064]  [<ffffffff811702e1>] sys_ioctl+0x91/0xa0
> [   48.900066]  [<ffffffff8140c3c2>] system_call_fastpath+0x16/0x1b
> [   48.900067] ---[ end trace 9a23b8b32b16a424 ]---

This is a known side-effect of a dying gpu. It essentially means that the
gpu refuses to wake up from deep-sleep states.

> and then
> 
> [   53.163526] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer
> elapsed... GPU hung
> [   53.165046] [drm] capturing error event; look for more information in
> /debug/dri/0/i915_error_state
> [   53.177356] [drm:i915_wait_request] *ERROR* i915_wait_request returns
> -11 (awaiting 1593 at 1592, next 1594)
> [   53.181979] [drm:init_ring_common] *ERROR* render ring initialization
> failed ctl 00000000 head 00000000 tail 00000000 start 00000000
> [   53.185522] [drm:init_ring_common] *ERROR* gen6 bsd ring initialization
> failed ctl 00000000 head 00000000 tail 00000000 start 00000000
> [   53.188558] [drm:init_ring_common] *ERROR* blt ring initialization
> failed ctl 00000000 head 00000000 tail 00000000 start 00000000
> [   55.330146] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer
> elapsed... GPU hung
> [   55.332202] [drm:i915_wait_request] *ERROR* i915_wait_request returns
> -11 (awaiting 1594 at 1591, next 1595)
> [   55.333258] [drm:i915_reset] *ERROR* GPU hanging too fast, declaring
> wedged!
> [   55.333260] [drm:i915_reset] *ERROR* Failed to reset chip.
> 
> Of course, I'd be willing to test out stuff. I'd need a bit of guide,
> however.

Can you please attach i915_error_state from debugfs (you need to retrigger
the issue)? It contains a gpu dump which is useful to diagnose the bug.

Yours, Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48