Quoting Chris Wilson (2018-05-18 11:09:33)
> Inside the live_hangcheck (reset) selftests, we occasionally see
> failures like
>
> <7>[ 239.094840] i915_gem_set_wedged rcs0
> <7>[ 239.094843] i915_gem_set_wedged current seqno 19a98, last 19a9a, hangcheck 0 [5158 ms]
> <7>[ 239.094846] i915_gem_set_wedged Reset count: 6239 (global 1)
> <7>[ 239.094848] i915_gem_set_wedged Requests:
> <7>[ 239.095052] i915_gem_set_wedged first 19a99 [e8c:5f] prio=1024 @ 5159ms: (null)
> <7>[ 239.095056] i915_gem_set_wedged last 19a9a [e81:1a] prio=139 @ 5159ms: igt/rcs0[5977]/1
> <7>[ 239.095059] i915_gem_set_wedged active 19a99 [e8c:5f] prio=1024 @ 5159ms: (null)
> <7>[ 239.095062] i915_gem_set_wedged [head 0220, postfix 0280, tail 02a8, batch 0xffffffff_ffffffff]
> <7>[ 239.100050] i915_gem_set_wedged ring->start: 0x00283000
> <7>[ 239.100053] i915_gem_set_wedged ring->head: 0x000001f8
> <7>[ 239.100055] i915_gem_set_wedged ring->tail: 0x000002a8
> <7>[ 239.100057] i915_gem_set_wedged ring->emit: 0x000002a8
> <7>[ 239.100059] i915_gem_set_wedged ring->space: 0x00000f10
> <7>[ 239.100085] i915_gem_set_wedged RING_START: 0x00283000
> <7>[ 239.100088] i915_gem_set_wedged RING_HEAD: 0x00000260
> <7>[ 239.100091] i915_gem_set_wedged RING_TAIL: 0x000002a8
> <7>[ 239.100094] i915_gem_set_wedged RING_CTL: 0x00000001
> <7>[ 239.100097] i915_gem_set_wedged RING_MODE: 0x00000300 [idle]
> <7>[ 239.100100] i915_gem_set_wedged RING_IMR: fffffefe
> <7>[ 239.100104] i915_gem_set_wedged ACTHD: 0x00000000_0000609c
> <7>[ 239.100108] i915_gem_set_wedged BBADDR: 0x00000000_0000609d
> <7>[ 239.100111] i915_gem_set_wedged DMA_FADDR: 0x00000000_00283260
> <7>[ 239.100114] i915_gem_set_wedged IPEIR: 0x00000000
> <7>[ 239.100117] i915_gem_set_wedged IPEHR: 0x02800000
> <7>[ 239.100120] i915_gem_set_wedged Execlist status: 0x00044052 00000002
> <7>[ 239.100124] i915_gem_set_wedged Execlist CSB read 5 [5 cached], write 5 [5 from hws], interrupt posted? no, tasklet queued? no (enabled)
> <7>[ 239.100128] i915_gem_set_wedged ELSP[0] count=1, ring->start=00283000, rq: 19a99 [e8c:5f] prio=1024 @ 5164ms: (null)
> <7>[ 239.100132] i915_gem_set_wedged ELSP[1] count=1, ring->start=00257000, rq: 19a9a [e81:1a] prio=139 @ 5164ms: igt/rcs0[5977]/1
> <7>[ 239.100135] i915_gem_set_wedged HW active? 0x5
> <7>[ 239.100250] i915_gem_set_wedged E 19a99 [e8c:5f] prio=1024 @ 5164ms: (null)
> <7>[ 239.100338] i915_gem_set_wedged E 19a9a [e81:1a] prio=139 @ 5164ms: igt/rcs0[5977]/1
> <7>[ 239.100340] i915_gem_set_wedged Queue priority: 139
> <7>[ 239.100343] i915_gem_set_wedged Q 0 [e98:19] prio=132 @ 5164ms: igt/rcs0[5977]/8
> <7>[ 239.100346] i915_gem_set_wedged Q 0 [e84:19] prio=121 @ 5165ms: igt/rcs0[5977]/2
> <7>[ 239.100349] i915_gem_set_wedged Q 0 [e87:19] prio=82 @ 5165ms: igt/rcs0[5977]/3
> <7>[ 239.100352] i915_gem_set_wedged Q 0 [e84:1a] prio=44 @ 5164ms: igt/rcs0[5977]/2
> <7>[ 239.100356] i915_gem_set_wedged Q 0 [e8b:19] prio=20 @ 5165ms: igt/rcs0[5977]/4
> <7>[ 239.100362] i915_gem_set_wedged drv_selftest [5894] waiting for 19a99
>
> where the GPU saw an arbitration point and idles; AND HAS NOT BEEN RESET!
> The RING_MODE indicates that is idle and has the STOP_RING bit set, so
> try clearing it.
>
> v2: Only clear the bit on restarting the ring, as we want to be sure the
> STOP_RING bit is kept if reset fails on wedging.
> v3: Spot when the ring state doesn't make sense when re-initialising the
> engine and dump it to the logs so that we don't have to wait for an
> error later and try to guess what happened earlier.
> v4: Prepare to print all the unexpected state, not just the first.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
This has gone through about 10 times without a live_hangcheck fail,
which is significantly better than the current state of affairs.
-Chris
> ---
> drivers/gpu/drm/i915/intel_lrc.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 3744f5750624..ba8411ba4abf 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1781,6 +1781,9 @@ static void enable_execlists(struct intel_engine_cs *engine)
> I915_WRITE(RING_MODE_GEN7(engine),
> _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE));
>
> + I915_WRITE(RING_MI_MODE(engine->mmio_base),
> + _MASKED_BIT_DISABLE(STOP_RING));
> +
> I915_WRITE(RING_HWS_PGA(engine->mmio_base),
> engine->status_page.ggtt_offset);
> POSTING_READ(RING_HWS_PGA(engine->mmio_base));
> @@ -1789,6 +1792,19 @@ static void enable_execlists(struct intel_engine_cs *engine)
> engine->execlists.csb_head = -1;
> }
>
> +static bool unexpected_starting_state(struct intel_engine_cs *engine)
> +{
> + struct drm_i915_private *dev_priv = engine->i915;
> + bool unexpected = false;
> +
> + if (I915_READ(RING_MI_MODE(engine->mmio_base)) & STOP_RING) {
> + DRM_DEBUG_DRIVER("STOP_RING still set in RING_MI_MODE\n");
> + unexpected = true;
> + }
> +
> + return unexpected;
> +}
> +
> static int gen8_init_common_ring(struct intel_engine_cs *engine)
> {
> struct intel_engine_execlists * const execlists = &engine->execlists;
> @@ -1801,6 +1817,12 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
> intel_engine_reset_breadcrumbs(engine);
> intel_engine_init_hangcheck(engine);
>
> + if (GEM_SHOW_DEBUG() && unexpected_starting_state(engine)) {
> + struct drm_printer p = drm_debug_printer(__func__);
> +
> + intel_engine_dump(engine, &p, NULL);
> + }
> +
> enable_execlists(engine);
>
> /* After a GPU reset, we may have requests to replay */
> --
> 2.17.0
>
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