From f63078abff0d2927c2f58f22b1082520def70865 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Winiarski?= <michal.winiarski@intel.com>
Date: Tue, 23 May 2017 12:23:59 +0200
Subject: [PATCH] drm/i915/guc: Skip port assign on first iteration of GuC dequeue
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Git-commit: f63078abff0d2927c2f58f22b1082520def70865
Patch-mainline: v4.13-rc1
References: FATE#322643 bsc#1055900

If port[0] is occupied and we're trying to dequeue request from
different context, we will inevitably hit BUG_ON in port_assign.
Let's skip it - similar to what we're doing in execlists counterpart.

Fixes: 77f0d0e925e8a0 ("drm/i915/execlists: Pack the count into the low bits of the port.request")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Wajdeczko <michal.wajdeczko@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170523102400.9614-2-michal.winiarski@intel.com
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/i915_guc_submission.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -681,7 +681,8 @@ static bool i915_guc_dequeue(struct inte
 					goto done;
 				}
 
-				port_assign(port, last);
+				if (submit)
+					port_assign(port, last);
 				port++;
 			}