drm/i915: Separate out the seqno-barrier from engine->get_seqno

In order to simplify future patches, extract the
lazy_coherency optimisation our of the engine->get_seqno() vfunc into
its own callback.

v2: Rename the barrier to engine->irq_seqno_barrier to try and better
reflect that the barrier is only required after the user interrupt before
reading the seqno (to ensure that the seqno update lands in time as we
do not have strict seqno-irq ordering on all platforms).

Reviewed-by: Dave Gordon <david.s.gordon@intel.com> [#v2]

v3: Comments for hangcheck paranoia. Mika wanted to keep the extra
barrier inside the hangcheck, just in case. I can argue that it doesn't
provide a barrier against anything, but the side-effects of applying the
barrier may prevent a false declaration of a hung GPU.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Dave Gordon <david.s.gordon@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460195877-20520-2-git-send-email-chris@chris-wilson.co.uk

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index ebbf4e400684..919c05ba9932 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -598,7 +598,7 @@ static int i915_gem_pageflip_info(struct seq_file *m, void *data)
 					   engine->name,
 					   i915_gem_request_get_seqno(work->flip_queued_req),
 					   dev_priv->next_seqno,
-					   engine->get_seqno(engine, true),
+					   engine->get_seqno(engine),
 					   i915_gem_request_completed(work->flip_queued_req, true));
 			} else
 				seq_printf(m, "Flip not associated with any ring\n");
@@ -730,7 +730,7 @@ static void i915_ring_seqno_info(struct seq_file *m,
 {
 	if (engine->get_seqno) {
 		seq_printf(m, "Current sequence (%s): %x\n",
-			   engine->name, engine->get_seqno(engine, false));
+			   engine->name, engine->get_seqno(engine));
 	}
 }
 
@@ -1346,8 +1346,8 @@ static int i915_hangcheck_info(struct seq_file *m, void *unused)
 	intel_runtime_pm_get(dev_priv);
 
 	for_each_engine_id(engine, dev_priv, id) {
-		seqno[id] = engine->get_seqno(engine, false);
 		acthd[id] = intel_ring_get_active_head(engine);
+		seqno[id] = engine->get_seqno(engine);
 	}
 
 	i915_get_extra_instdone(dev, instdone);