[PATCH v1 2/2] 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.

Signed-off-by: Naresh Kumar Kachhi <naresh.kumar.kachhi@intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h         | 2 ++
 drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
 drivers/gpu/drm/i915/intel_ringbuffer.h | 2 ++
 3 files changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 146609a..6174fda 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -748,6 +748,7 @@ enum punit_power_well {
 #define RING_INSTPS(base)	((base)+0x70)
 #define RING_DMA_FADD(base)	((base)+0x78)
 #define RING_INSTPM(base)	((base)+0xc0)
+#define RING_MI_MODE(base)	((base)+0x9c)
 #define INSTPS		0x02070 /* 965+ only */
 #define INSTDONE1	0x0207c /* 965+ only */
 #define ACTHD_I965	0x02074
@@ -824,6 +825,7 @@ enum punit_power_well {
 # define VS_TIMER_DISPATCH				(1 << 6)
 # define MI_FLUSH_ENABLE				(1 << 12)
 # define ASYNC_FLIP_PERF_DISABLE			(1 << 14)
+# define MODE_IDLE					(1 << 9)
 
 #define GEN6_GT_MODE	0x20d0
 #define GEN7_GT_MODE	0x7008
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 42b4001..1bd3b58 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -982,6 +982,9 @@ 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 |
 					      INSTPM_SYNC_FLUSH));
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 09af920..f11ceb2 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -33,6 +33,8 @@ struct  intel_hw_status_page {
 #define I915_READ_IMR(ring) I915_READ(RING_IMR((ring)->mmio_base))
 #define I915_WRITE_IMR(ring, val) I915_WRITE(RING_IMR((ring)->mmio_base), val)
 
+#define I915_READ_MODE(ring) I915_READ(RING_MI_MODE((ring)->mmio_base))
+
 enum intel_ring_hangcheck_action {
 	HANGCHECK_IDLE = 0,
 	HANGCHECK_WAIT,
-- 
1.8.5.3