An odd and highly unlikely path caught us out. On delayed submission
(due to an asynchronous reset handler), we poked the priority_hint and
kicked the tasklet. However, we had already marked the device as wedged
and swapped out the tasklet for a no-op. The result was that we never
cleared the priority hint and became upset when we later checked.

<0> [574.303565] i915_sel-6278    2.... 481822445us : __i915_subtests: Running intel_execlists_live_selftests/live_error_interrupt
<0> [574.303565] i915_sel-6278    2.... 481822472us : __engine_unpark: 0000:00:02.0 rcs0:
<0> [574.303565] i915_sel-6278    2.... 481822491us : __gt_unpark: 0000:00:02.0
<0> [574.303565] i915_sel-6278    2.... 481823220us : execlists_context_reset: 0000:00:02.0 rcs0: context:f4ee reset
<0> [574.303565] i915_sel-6278    2.... 481824830us : __intel_context_active: 0000:00:02.0 rcs0: context:f51b active
<0> [574.303565] i915_sel-6278    2.... 481825258us : __intel_context_do_pin: 0000:00:02.0 rcs0: context:f51b pin ring:{start:00006000, head:0000, tail:0000}
<0> [574.303565] i915_sel-6278    2.... 481825311us : __i915_request_commit: 0000:00:02.0 rcs0: fence f51b:2, current 0
<0> [574.303565] i915_sel-6278    2d..1 481825347us : __i915_request_submit: 0000:00:02.0 rcs0: fence f51b:2, current 0
<0> [574.303565] i915_sel-6278    2d..1 481825363us : trace_ports: 0000:00:02.0 rcs0: submit { f51b:2, 0:0 }
<0> [574.303565] i915_sel-6278    2.... 481826809us : __intel_context_active: 0000:00:02.0 rcs0: context:f51c active
<0> [574.303565]   <idle>-0       7d.h2 481827326us : cs_irq_handler: 0000:00:02.0 rcs0: CS error: 1
<0> [574.303565]   <idle>-0       7..s1 481827377us : process_csb: 0000:00:02.0 rcs0: cs-irq head=3, tail=4
<0> [574.303565]   <idle>-0       7..s1 481827379us : process_csb: 0000:00:02.0 rcs0: csb[4]: status=0x10000001:0x00000000
<0> [574.305593]   <idle>-0       7..s1 481827385us : trace_ports: 0000:00:02.0 rcs0: promote { f51b:2*, 0:0 }
<0> [574.305611]   <idle>-0       7..s1 481828179us : execlists_reset: 0000:00:02.0 rcs0: reset for CS error
<0> [574.305611] i915_sel-6278    2.... 481828284us : __intel_context_do_pin: 0000:00:02.0 rcs0: context:f51c pin ring:{start:00007000, head:0000, tail:0000}
<0> [574.305611] i915_sel-6278    2.... 481828345us : __i915_request_commit: 0000:00:02.0 rcs0: fence f51c:2, current 0
<0> [574.305611]   <idle>-0       7dNs2 481847823us : __i915_request_unsubmit: 0000:00:02.0 rcs0: fence f51b:2, current 1
<0> [574.305611]   <idle>-0       7dNs2 481847857us : execlists_hold: 0000:00:02.0 rcs0: fence f51b:2, current 1 on hold
<0> [574.305611]   <idle>-0       7.Ns1 481847863us : intel_engine_reset: 0000:00:02.0 rcs0: flags=4
<0> [574.305611]   <idle>-0       7.Ns1 481847945us : execlists_reset_prepare: 0000:00:02.0 rcs0: depth<-1
<0> [574.305611]   <idle>-0       7.Ns1 481847946us : intel_engine_stop_cs: 0000:00:02.0 rcs0:
<0> [574.305611]   <idle>-0       7.Ns1 538584284us : intel_engine_stop_cs: 0000:00:02.0 rcs0: timed out on STOP_RING -> IDLE
<0> [574.305611]   <idle>-0       7.Ns1 538584347us : __intel_gt_reset: 0000:00:02.0 engine_mask=1
<0> [574.305611]   <idle>-0       7.Ns1 538584406us : execlists_reset_rewind: 0000:00:02.0 rcs0:
<0> [574.305611]   <idle>-0       7dNs2 538585050us : __i915_request_reset: 0000:00:02.0 rcs0: fence f51b:2, current 1 guilty? yes
<0> [574.305611]   <idle>-0       7dNs2 538585063us : __execlists_reset: 0000:00:02.0 rcs0: replay {head:0000, tail:0068}
<0> [574.306565]   <idle>-0       7.Ns1 538588457us : intel_engine_cancel_stop_cs: 0000:00:02.0 rcs0:
<0> [574.306565]   <idle>-0       7dNs2 538588462us : __i915_request_submit: 0000:00:02.0 rcs0: fence f51c:2, current 0
<0> [574.306565]   <idle>-0       7dNs2 538588471us : trace_ports: 0000:00:02.0 rcs0: submit { f51c:2, 0:0 }
<0> [574.306565]   <idle>-0       7.Ns1 538588474us : execlists_reset_finish: 0000:00:02.0 rcs0: depth->1
<0> [574.306565] kworker/-202     2.... 538588755us : i915_request_retire: 0000:00:02.0 rcs0: fence f51c:2, current 2
<0> [574.306565] ksoftirq-46      7..s. 538588773us : process_csb: 0000:00:02.0 rcs0: cs-irq head=11, tail=1
<0> [574.306565] ksoftirq-46      7..s. 538588774us : process_csb: 0000:00:02.0 rcs0: csb[0]: status=0x10000001:0x00000000
<0> [574.306565] ksoftirq-46      7..s. 538588776us : trace_ports: 0000:00:02.0 rcs0: promote { f51c:2!, 0:0 }
<0> [574.306565] ksoftirq-46      7..s. 538588778us : process_csb: 0000:00:02.0 rcs0: csb[1]: status=0x10000018:0x00000020
<0> [574.306565] ksoftirq-46      7..s. 538588779us : trace_ports: 0000:00:02.0 rcs0: completed { f51c:2!, 0:0 }
<0> [574.306565] kworker/-202     2.... 538588826us : intel_context_unpin: 0000:00:02.0 rcs0: context:f51c unpin
<0> [574.306565] i915_sel-6278    6.... 538589663us : __intel_gt_set_wedged.part.32: 0000:00:02.0 start
<0> [574.306565] i915_sel-6278    6.... 538589667us : execlists_reset_prepare: 0000:00:02.0 rcs0: depth<-0
<0> [574.306565] i915_sel-6278    6.... 538589710us : intel_engine_stop_cs: 0000:00:02.0 rcs0:
<0> [574.306565] i915_sel-6278    6.... 538589732us : execlists_reset_prepare: 0000:00:02.0 bcs0: depth<-0
<0> [574.307591] i915_sel-6278    6.... 538589733us : intel_engine_stop_cs: 0000:00:02.0 bcs0:
<0> [574.307591] i915_sel-6278    6.... 538589757us : execlists_reset_prepare: 0000:00:02.0 vcs0: depth<-0
<0> [574.307591] i915_sel-6278    6.... 538589758us : intel_engine_stop_cs: 0000:00:02.0 vcs0:
<0> [574.307591] i915_sel-6278    6.... 538589771us : execlists_reset_prepare: 0000:00:02.0 vcs1: depth<-0
<0> [574.307591] i915_sel-6278    6.... 538589772us : intel_engine_stop_cs: 0000:00:02.0 vcs1:
<0> [574.307591] i915_sel-6278    6.... 538589778us : execlists_reset_prepare: 0000:00:02.0 vecs0: depth<-0
<0> [574.307591] i915_sel-6278    6.... 538589780us : intel_engine_stop_cs: 0000:00:02.0 vecs0:
<0> [574.307591] i915_sel-6278    6.... 538589786us : __intel_gt_reset: 0000:00:02.0 engine_mask=ff
<0> [574.307591] i915_sel-6278    6.... 538591175us : execlists_reset_cancel: 0000:00:02.0 rcs0:
<0> [574.307591] i915_sel-6278    6.... 538591970us : execlists_reset_cancel: 0000:00:02.0 bcs0:
<0> [574.307591] i915_sel-6278    6.... 538591982us : execlists_reset_cancel: 0000:00:02.0 vcs0:
<0> [574.307591] i915_sel-6278    6.... 538591996us : execlists_reset_cancel: 0000:00:02.0 vcs1:
<0> [574.307591] i915_sel-6278    6.... 538592759us : execlists_reset_cancel: 0000:00:02.0 vecs0:
<0> [574.307591] i915_sel-6278    6.... 538592977us : execlists_reset_finish: 0000:00:02.0 rcs0: depth->0
<0> [574.307591] i915_sel-6278    6.N.. 538592996us : execlists_reset_finish: 0000:00:02.0 bcs0: depth->0
<0> [574.307591] i915_sel-6278    6.N.. 538593023us : execlists_reset_finish: 0000:00:02.0 vcs0: depth->0
<0> [574.307591] i915_sel-6278    6.N.. 538593037us : execlists_reset_finish: 0000:00:02.0 vcs1: depth->0
<0> [574.307591] i915_sel-6278    6.N.. 538593051us : execlists_reset_finish: 0000:00:02.0 vecs0: depth->0
<0> [574.307591] i915_sel-6278    6.... 538593407us : __intel_gt_set_wedged.part.32: 0000:00:02.0 end
<0> [574.307591] kworker/-210     7d..1 551958381us : execlists_unhold: 0000:00:02.0 rcs0: fence f51b:2, current 2 hold release
<0> [574.307591] i915_sel-6278    0.... 559490788us : i915_request_retire: 0000:00:02.0 rcs0: fence f51b:2, current 2
<0> [574.307591] i915_sel-6278    0.... 559490793us : intel_context_unpin: 0000:00:02.0 rcs0: context:f51b unpin
<0> [574.307591] i915_sel-6278    0.... 559490798us : __engine_park: 0000:00:02.0 rcs0: parked
<0> [574.307591] i915_sel-6278    0.... 559490982us : __intel_context_retire: 0000:00:02.0 rcs0: context:f51c retire runtime: { total:30004ns, avg:30004ns }
<0> [574.307591] i915_sel-6278    0.... 559491372us : __engine_park: __engine_park:261 GEM_BUG_ON(engine->execlists.queue_priority_hint != (-((int)(~0U >> 1)) - 1))
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200227085723.1961649-9-chris@chris-wilson.co.uk