drm/i915/selftests: Always flush before unpining after writing

Be consistent, and even when we know we had used a WC, flush the mapped
object after writing into it. The flush understands the mapping type and
will only clflush if !I915_MAP_WC, but will always insert a wmb [sfence]
so that we can be sure that all writes are visible.

v2: Add the unconditional wmb so we are know that we always flush the
writes to memory/HW at that point.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200511141304.599-1-chris@chris-wilson.co.uk

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c
index ffdfcb3805b5..6014e8dfcbb1 100644
--- a/drivers/gpu/drm/i915/selftests/i915_request.c
+++ b/drivers/gpu/drm/i915/selftests/i915_request.c
@@ -816,10 +816,12 @@ static int recursive_batch_resolve(struct i915_vma *batch)
 		return PTR_ERR(cmd);
 
 	*cmd = MI_BATCH_BUFFER_END;
-	intel_gt_chipset_flush(batch->vm->gt);
 
+	__i915_gem_object_flush_map(batch->obj, 0, sizeof(*cmd));
 	i915_gem_object_unpin_map(batch->obj);
 
+	intel_gt_chipset_flush(batch->vm->gt);
+
 	return 0;
 }
 
@@ -1060,9 +1062,12 @@ out_request:
 					      I915_MAP_WC);
 		if (!IS_ERR(cmd)) {
 			*cmd = MI_BATCH_BUFFER_END;
-			intel_gt_chipset_flush(engine->gt);
 
+			__i915_gem_object_flush_map(request[idx]->batch->obj,
+						    0, sizeof(*cmd));
 			i915_gem_object_unpin_map(request[idx]->batch->obj);
+
+			intel_gt_chipset_flush(engine->gt);
 		}
 
 		i915_vma_put(request[idx]->batch);