[Intel-gfx] [PATCH] drm/i915: Replace irq_seqno_barrier on hws write with a clflush

[Chris Wilson]

On Thu, Mar 16, 2017 at 04:15:35PM +0200, Mika Kuoppala wrote:
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > When manually overwriting the HWS, rather than assume irq_seqno_barrier
> > does the right thing, we can explicitly flush the cacheline instead.
> > This avoids us calling the engine->irq_seqno_barrier() from an illegal
> > context:
> >
> > [ 1472.651797] BUG: scheduling while atomic: migration/0/11/0x00000002
> > [ 1472.651807] Modules linked in: ctr ccm arc4 snd_hda_codec_hdmi bnep rfcomm iwldvm snd_hda_codec_conexant snd_hda_codec_generic snd_hda_intel mac80211 snd_hda_codec snd_hda_core snd_pcm dm_multipath snd_hwdep intel_powerclamp coretemp snd_seq_midi crct10dif_pclmul snd_seq_midi_event crc32_pclmul iwlwifi ghash_clmulni_intel btusb snd_rawmidi btrtl aesni_intel btbcm aes_x86_64 crypto_simd btintel cryptd glue_helper bluetooth snd_seq cfg80211 snd_timer snd_seq_device intel_ips binfmt_misc snd mei_me soundcore mei dm_mirror dm_region_hash dm_log i915 intel_gtt i2c_algo_bit drm_kms_helper cfbfillrect syscopyarea cfbimgblt sysfillrect sysimgblt fb_sys_fops cfbcopyarea prime_numbers e1000e drm ahci libahci
> > [ 1472.651897] CPU: 0 PID: 11 Comm: migration/0 Tainted: G     U          4.11.0-rc1+ #203
> > [ 1472.651899] Hardware name: LENOVO 514328U/514328U, BIOS 6QET44WW (1.14 ) 04/20/2010
> > [ 1472.651900] Call Trace:
> > [ 1472.651913]  dump_stack+0x63/0x90
> > [ 1472.651922]  __schedule_bug+0x5d/0x6b
> > [ 1472.651930]  __schedule+0x46a/0x5f0
> > [ 1472.651934]  schedule+0x38/0x90
> > [ 1472.651938]  schedule_hrtimeout_range_clock+0x85/0x110
> > [ 1472.651945]  ? hrtimer_init+0x10/0x10
> > [ 1472.651949]  schedule_hrtimeout_range+0xe/0x10
> > [ 1472.651952]  usleep_range+0x4d/0x60
> > [ 1472.652037]  gen5_seqno_barrier+0x13/0x20 [i915]
> > [ 1472.652101]  intel_engine_init_global_seqno+0xd7/0x160 [i915]
> > [ 1472.652160]  __i915_gem_set_wedged_BKL+0xa0/0x180 [i915]
> > [ 1472.652166]  multi_cpu_stop+0xbb/0xe0
> > [ 1472.652170]  ? cpu_stop_queue_work+0x90/0x90
> > [ 1472.652174]  cpu_stopper_thread+0x82/0x110
> > [ 1472.652179]  smpboot_thread_fn+0x137/0x190
> > [ 1472.652184]  kthread+0xf7/0x130
> > [ 1472.652187]  ? sort_range+0x20/0x20
> > [ 1472.652191]  ? kthread_park+0x90/0x90
> > [ 1472.652195]  ret_from_fork+0x2c/0x40
> >
> > Testcase: igt/gem_eio #ilk
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> 
> Reviewed-by: Mika Kuoppala <mika.kuoppala at intel.com>

Ta, pushed to keep CI busy (proving the sporadic incompletes are gone).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre