drm/i915/selftests: Wait for the context switch

As we require a context switch to ensure that the current context is
switched out and saved to memory, perform an explicit switch to the
kernel context and wait for it.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/1336
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228082330.2411941-18-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c
index 2c27b34..175bede 100644 (file)
--- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
+++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
@@ -4015,6 +4015,32 @@ static int emit_semaphore_signal(struct intel_context *ce, void *slot)
        return 0;
 }
 
+static int context_flush(struct intel_context *ce, long timeout)
+{
+       struct i915_request *rq;
+       struct dma_fence *fence;
+       int err = 0;
+
+       rq = intel_engine_create_kernel_request(ce->engine);
+       if (IS_ERR(rq))
+               return PTR_ERR(rq);
+
+       fence = i915_active_fence_get(&ce->timeline->last_request);
+       if (fence) {
+               i915_request_await_dma_fence(rq, fence);
+               dma_fence_put(fence);
+       }
+
+       rq = i915_request_get(rq);
+       i915_request_add(rq);
+       if (i915_request_wait(rq, 0, timeout) < 0)
+               err = -ETIME;
+       i915_request_put(rq);
+
+       rmb(); /* We know the request is written, make sure all state is too! */
+       return err;
+}
+
 static int live_lrc_layout(void *arg)
 {
        struct intel_gt *gt = arg;
@@ -4638,18 +4664,10 @@ static int __lrc_timestamp(const struct lrc_timestamp *arg, bool preempt)
                wmb();
        }
 
-       if (i915_request_wait(rq, 0, HZ / 2) < 0) {
-               err = -ETIME;
-               goto err;
-       }
-
-       /* and wait for switch to kernel */
-       if (igt_flush_test(arg->engine->i915)) {
-               err = -EIO;
+       /* And wait for switch to kernel (to save our context to memory) */
+       err = context_flush(arg->ce[0], HZ / 2);
+       if (err)
                goto err;
-       }
-
-       rmb();
 
        if (!timestamp_advanced(arg->poison, slot[1])) {
                pr_err("%s(%s): invalid timestamp on restore, context:%x, request:%x\n",