[Intel-gfx] [PATCH 1/4] drm/i915: Initialize hardware semaphore state on ring init

[Mika Kuoppala]

Hardware status page needs to have proper seqno set
as our initial seqno can be arbitrary. If initial seqno is close
to wrap boundary on init and i915_seqno_passed() (31bit space)
refers to hw status page which contains zero, errorneous result
will be returned.

References: https://bugs.freedesktop.org/show_bug.cgi?id=58230
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c         |    6 +++---
 drivers/gpu/drm/i915/intel_ringbuffer.c |   18 ++++++++++++++++--
 drivers/gpu/drm/i915/intel_ringbuffer.h |    3 ++-
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d15c862..8dc5cc1 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1954,7 +1954,7 @@ i915_gem_handle_seqno_wrap(struct drm_device *dev)
 
 	/* Finally reset hw state */
 	for_each_ring(ring, dev_priv, i) {
-		ret = intel_ring_handle_seqno_wrap(ring);
+		ret = intel_ring_init_seqno(ring, 0);
 		if (ret)
 			return ret;
 
@@ -3933,6 +3933,8 @@ i915_gem_init_hw(struct drm_device *dev)
 
 	i915_gem_init_swizzling(dev);
 
+	dev_priv->next_seqno = dev_priv->last_seqno = (u32)~0 - 0x1000;
+
 	ret = intel_init_render_ring_buffer(dev);
 	if (ret)
 		return ret;
@@ -3949,8 +3951,6 @@ i915_gem_init_hw(struct drm_device *dev)
 			goto cleanup_bsd_ring;
 	}
 
-	dev_priv->next_seqno = (u32)-1 - 0x1000;
-
 	/*
 	 * XXX: There was some w/a described somewhere suggesting loading
 	 * contexts before PPGTT.
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 69bbe7b..7e38511f 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1171,6 +1171,10 @@ static int intel_init_ring_buffer(struct drm_device *dev,
 	if (IS_I830(ring->dev) || IS_845G(ring->dev))
 		ring->effective_size -= 128;
 
+	ret = intel_ring_init_seqno(ring, dev_priv->last_seqno);
+	if (ret)
+		goto err_unmap;
+
 	return 0;
 
 err_unmap:
@@ -1418,7 +1422,7 @@ int intel_ring_begin(struct intel_ring_buffer *ring,
 	return __intel_ring_begin(ring, num_dwords * sizeof(uint32_t));
 }
 
-int intel_ring_handle_seqno_wrap(struct intel_ring_buffer *ring)
+int intel_ring_init_seqno(struct intel_ring_buffer *ring, u32 seqno)
 {
 	int ret;
 
@@ -1427,7 +1431,7 @@ int intel_ring_handle_seqno_wrap(struct intel_ring_buffer *ring)
 	if (INTEL_INFO(ring->dev)->gen < 6)
 		return 0;
 
-	ret = __intel_ring_begin(ring, 6 * sizeof(uint32_t));
+	ret = __intel_ring_begin(ring, 10 * sizeof(uint32_t));
 	if (ret)
 		return ret;
 
@@ -1435,8 +1439,18 @@ int intel_ring_handle_seqno_wrap(struct intel_ring_buffer *ring)
 	 * post-wrap semaphore waits completing immediately. Clear them. */
 	update_mboxes(ring, ring->signal_mbox[0]);
 	update_mboxes(ring, ring->signal_mbox[1]);
+	intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
+	intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
+	intel_ring_emit(ring, seqno);
+	intel_ring_emit(ring, MI_USER_INTERRUPT);
 	intel_ring_advance(ring);
 
+	/* Wait until mboxes have actually cleared before pushing
+	 * anything to the rings */
+	ret = ring_wait_for_space(ring, ring->size - 8);
+	if (ret)
+		return ret;
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index b4a533e..cb5a663 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -196,7 +196,8 @@ static inline void intel_ring_emit(struct intel_ring_buffer *ring,
 }
 void intel_ring_advance(struct intel_ring_buffer *ring);
 int __must_check intel_ring_idle(struct intel_ring_buffer *ring);
-int __must_check intel_ring_handle_seqno_wrap(struct intel_ring_buffer *ring);
+int __must_check intel_ring_init_seqno(struct intel_ring_buffer *ring,
+				       u32 seqno);
 int intel_ring_flush_all_caches(struct intel_ring_buffer *ring);
 int intel_ring_invalidate_all_caches(struct intel_ring_buffer *ring);
 
-- 
1.7.9.5