From a3df2c857c103b1103c9d578d68193a6fbe63c61 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 21 Sep 2017 22:09:03 +0100
Subject: [PATCH] drm/i915: Confirm request->global_seqno after spin completion
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Git-commit: a3df2c857c103b1103c9d578d68193a6fbe63c61
Patch-mainline: v4.15-rc1
References: FATE#322643 bsc#1055900

After we see our target seqno has been completed by the hw, we need to
confirm that it still matches the request (as it may have been preempted
before the spin completes). If the request no longer matches the target
seqno, we need to restart the wait to reacquire that seqno.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170921210903.18337-1-chris@chris-wilson.co.uk
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/i915_gem_request.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -1040,12 +1040,9 @@ bool __i915_spin_request(const struct dr
 	irq = atomic_read(&engine->irq_count);
 	timeout_us += local_clock_us(&cpu);
 	do {
-		if (seqno != i915_gem_request_global_seqno(req))
-			break;
-
 		if (i915_seqno_passed(intel_engine_get_seqno(req->engine),
 				      seqno))
-			return true;
+			return seqno == i915_gem_request_global_seqno(req);
 
 		/* Seqno are meant to be ordered *before* the interrupt. If
 		 * we see an interrupt without a corresponding seqno advance,