From 6492ca79c823f508d3b28526b419c9c584388970 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 21 Jul 2017 17:11:01 +0100
Subject: [PATCH] drm/i915: Enforce that CS packets are qword aligned
Git-commit: 6492ca79c823f508d3b28526b419c9c584388970
Patch-mainline: v4.14-rc1
References: FATE#322643 bsc#1055900

We require the caller to ensure that the packets they wish to emit into
the CS ring are qword aligned (i.e. have an even number of dwords).
Double check this.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170721161101.1618-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Takashi Iwai <tiwai@suse.de>

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

--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1712,6 +1712,9 @@ u32 *intel_ring_begin(struct drm_i915_ge
 	unsigned int total_bytes;
 	u32 *cs;
 
+	/* Packets must be qword aligned. */
+	GEM_BUG_ON(num_dwords & 1);
+
 	total_bytes = bytes + req->reserved_space;
 	GEM_BUG_ON(total_bytes > ring->effective_size);