[PATCH v2 3/3] drm/i915: warn if ring is active before sync flush

[naresh.kumar.kachhi@intel.com]

From: Naresh Kumar Kachhi <naresh.kumar.kachhi@intel.com>

Based on Bspec the command parser must be stopped prior to
issuing sync flush. This should be done by the caller of
intel_ring_setup_status_page. Patch adds a warning if it is
not done.

v2: rebased based on new patch (wait for ring to become idle)

Signed-off-by: Naresh Kumar Kachhi <naresh.kumar.kachhi@intel.com>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 4da2211..6ac6569 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -987,6 +987,8 @@ void intel_ring_setup_status_page(struct intel_ring_buffer *ring)
 	/* Flush the TLB for this page */
 	if (INTEL_INFO(dev)->gen >= 6) {
 		u32 reg = RING_INSTPM(ring->mmio_base);
+		/* ring should be idle before issuing a sync flush*/
+		WARN_ON((I915_READ_MODE(ring) & MODE_IDLE) == 0);
 
 		I915_WRITE(reg,
 			   _MASKED_BIT_ENABLE(INSTPM_TLB_INVALIDATE |
-- 
1.8.5.3