[Intel-gfx] [PATCH] drm/i915: Enforce that CS packets are qword aligned

[Chris Wilson]

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 at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index aa59290cb8bf..0b06f66507a0 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1397,6 +1397,9 @@ u32 *intel_ring_begin(struct drm_i915_gem_request *req,
 	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);
 
-- 
2.13.3