drm/i915: Wait first for submission, before waiting for request completion

In future patches, we will no longer be able to wait on a static global
seqno and instead have to break our wait up into phases. First we wait
for the global seqno assignment (upon submission to hardware), and once
submitted we wait for the hardware to complete.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-25-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 16d38f87f0a7a992b366e955ae28822fdc8cb183..03ae85a1eefb018720c4cb66cfbbece31b1d3c81 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -789,6 +789,49 @@ bool __i915_spin_request(const struct drm_i915_gem_request *req,
        return false;
 }
 
+static long
+__i915_request_wait_for_submit(struct drm_i915_gem_request *request,
+                              unsigned int flags,
+                              long timeout)
+{
+       const int state = flags & I915_WAIT_INTERRUPTIBLE ?
+               TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
+       wait_queue_head_t *q = &request->i915->gpu_error.wait_queue;
+       DEFINE_WAIT(reset);
+       DEFINE_WAIT(wait);
+
+       if (flags & I915_WAIT_LOCKED)
+               add_wait_queue(q, &reset);
+
+       do {
+               prepare_to_wait(&request->submit.wait, &wait, state);
+
+               if (i915_sw_fence_done(&request->submit))
+                       break;
+
+               if (flags & I915_WAIT_LOCKED &&
+                   i915_reset_in_progress(&request->i915->gpu_error)) {
+                       __set_current_state(TASK_RUNNING);
+                       i915_reset(request->i915);
+                       reset_wait_queue(q, &reset);
+                       continue;
+               }
+
+               if (signal_pending_state(state, current)) {
+                       timeout = -ERESTARTSYS;
+                       break;
+               }
+
+               timeout = io_schedule_timeout(timeout);
+       } while (timeout);
+       finish_wait(&request->submit.wait, &wait);
+
+       if (flags & I915_WAIT_LOCKED)
+               remove_wait_queue(q, &reset);
+
+       return timeout;
+}
+
 /**
  * i915_wait_request - wait until execution of request has finished
  * @req: the request to wait upon
@@ -833,6 +876,14 @@ long i915_wait_request(struct drm_i915_gem_request *req,
 
        trace_i915_gem_request_wait_begin(req);
 
+       if (!i915_sw_fence_done(&req->submit)) {
+               timeout = __i915_request_wait_for_submit(req, flags, timeout);
+               if (timeout < 0)
+                       goto complete;
+
+               GEM_BUG_ON(!i915_sw_fence_done(&req->submit));
+       }
+
        /* Optimistic short spin before touching IRQs */
        if (i915_spin_request(req, state, 5))
                goto complete;