drm/i915: Assert that we always complete a submission to guc/execlists

The continual resubmission model for execlists (and emulated over guc)
requires that we keep feeding requests into the HW in order to generate
more CS interrupts to drain the rest of the queue. Add a couple of
asserts to ensure that we don't skip a cycle and come to a grinding
halt.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180215162553.23348-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
index b43b58c..946766b 100644 (file)
--- a/drivers/gpu/drm/i915/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/intel_guc_submission.c
@@ -747,6 +747,12 @@ done:
                execlists_set_active(execlists, EXECLISTS_ACTIVE_USER);
                guc_submit(engine);
        }
+
+       /* We must always keep the beast fed if we have work piled up */
+       GEM_BUG_ON(port_isset(execlists->port) &&
+                  !execlists_is_active(execlists, EXECLISTS_ACTIVE_USER));
+       GEM_BUG_ON(execlists->first && !port_isset(execlists->port));
+
 unlock:
        spin_unlock_irq(&engine->timeline->lock);
 }

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index c2c8380..6fbe1a8 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -642,6 +642,12 @@ done:
        execlists->first = rb;
        if (submit)
                port_assign(port, last);
+
+       /* We must always keep the beast fed if we have work piled up */
+       GEM_BUG_ON(port_isset(execlists->port) &&
+                  !execlists_is_active(execlists, EXECLISTS_ACTIVE_USER));
+       GEM_BUG_ON(execlists->first && !port_isset(execlists->port));
+
 unlock:
        spin_unlock_irq(&engine->timeline->lock);