[Intel-gfx] Warning: Broadwell/i915: Unclaimed register detected before reading register 0x130040

[Daniel Vetter]

On Mon, May 25, 2015 at 08:04:45PM +0200, Dominik Brodowski wrote:
> Hey,
> 
> this just popped up in the dmesg of my Dell XPS 13 -- the system seems to
> run well, but still, it asks about being cut and sent, so here it is. It is
> on 4.1.0-rc4+ (Linus' tree as of May 24th, around 3pm UTC -- don't have the
> git commit ID anymore).

Can you please boot with i915.mmio_debug=10 and try to reproduce the
issue? That should light more onto this issue. And yup it's indeed a bug
since this means a register write has been dropped by the hardware, which
often tends to be somewhat harmless except when it doesn't ;-)
-Daniel

> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1167 at /home/brodo/local/kernel/git/linux/drivers/gpu/drm/i915/intel_uncore.c:566 hsw_unclaimed_reg_debug+0x7d/0xa0()
> Unclaimed register detected before reading register 0x130040
> Modules linked in:
> CPU: 0 PID: 1167 Comm: Xorg Not tainted 4.1.0-rc4+ #1
> Hardware name: Dell Inc. XPS 13 9343/0TM99H, BIOS A03 03/25/2015
>  ffffffffb39694d8 ffff88020e14b998 ffffffffb322906f 0000000080000001
>  ffff88020e14b9e8 ffff88020e14b9d8 ffffffffb272ca8a ffff88020e14b9a8
>  ffff880215190000 0000000000130040 ffff880215bfd800 0000000000130040
> Call Trace:
>  [<ffffffffb322906f>] dump_stack+0x4f/0x7b
>  [<ffffffffb272ca8a>] warn_slowpath_common+0x8a/0xc0
>  [<ffffffffb272cb06>] warn_slowpath_fmt+0x46/0x50
>  [<ffffffffb2be63cd>] hsw_unclaimed_reg_debug+0x7d/0xa0
>  [<ffffffffb2be84b6>] gen6_read32+0x56/0x1c0
>  [<ffffffffb2c096e6>] hsw_disable_pc8+0x36/0x2c0
>  [<ffffffffb2b98e60>] intel_runtime_resume+0x160/0x1b0
>  [<ffffffffb2a94bdf>] pci_pm_runtime_resume+0x7f/0xc0
>  [<ffffffffb2a94b60>] ? pci_restore_standard_config+0x50/0x50
>  [<ffffffffb2c5c8f6>] __rpm_callback+0x36/0x90
>  [<ffffffffb2c5c976>] rpm_callback+0x26/0xa0
>  [<ffffffffb2c5dcc6>] rpm_resume+0x496/0x670
>  [<ffffffffb2756209>] ? preempt_count_add+0x79/0xc0
>  [<ffffffffb2c5dee0>] __pm_runtime_resume+0x40/0x60
>  [<ffffffffb2ba7fd5>] intel_runtime_pm_get+0x55/0x80
>  [<ffffffffb2bc6989>] i915_gem_free_object+0x29/0x360
>  [<ffffffffb2b6b417>] drm_gem_object_free+0x27/0x40
>  [<ffffffffb2b6b548>] drm_gem_object_handle_unreference_unlocked+0x118/0x130
>  [<ffffffffb2b6b6d4>] drm_gem_handle_delete+0xb4/0x100
>  [<ffffffffb2fde8ab>] ? sock_recvmsg+0x3b/0x50
>  [<ffffffffb2b6ba95>] drm_gem_close_ioctl+0x25/0x30
>  [<ffffffffb2b6c4a5>] drm_ioctl+0x1a5/0x6a0
>  [<ffffffffb2869672>] ? do_readv_writev+0x1b2/0x260
>  [<ffffffffb323187a>] ? _raw_spin_unlock_irqrestore+0x2a/0x60
>  [<ffffffffb2a5b804>] ? timerqueue_del+0x24/0x70
>  [<ffffffffb278b2fe>] ? __remove_hrtimer+0x4e/0xe0
>  [<ffffffffb287c110>] do_vfs_ioctl+0x2e0/0x4e0
>  [<ffffffffb2886482>] ? __fget+0x72/0xb0
>  [<ffffffffb287c391>] SyS_ioctl+0x81/0xa0
>  [<ffffffffb3232017>] system_call_fastpath+0x12/0x6a
> ---[ end trace 8ff5864d3e587195 ]---
> 
> Best,
> 	Dominik



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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch