[Intel-gfx] [PATCH 1/2] drm/i915: Don't emit semaphore wait if wrap happened
Mika Kuoppala
mika.kuoppala at linux.intel.com
Mon Dec 10 12:56:16 CET 2012
If wrap just happened we need to prevent emitting waits for
pre wrap values. Detect this and emit no-ops instead.
v2: Use olr > seqno to detect wrap instead of *seqno == 0
as suggested by Chris Wilson.
v3: Use last used seqno to detect the wraparound. From
Chris Wilson
References: https://bugs.freedesktop.org/show_bug.cgi?id=57967
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 2 +-
drivers/gpu/drm/i915/i915_gem.c | 3 ++-
drivers/gpu/drm/i915/intel_ringbuffer.c | 26 +++++++++++++++++++++-----
3 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 2ab476d..9da6782 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -671,7 +671,7 @@ typedef struct drm_i915_private {
struct pci_dev *bridge_dev;
struct intel_ring_buffer ring[I915_NUM_RINGS];
- uint32_t next_seqno;
+ uint32_t last_seqno, next_seqno;
drm_dma_handle_t *status_page_dmah;
struct resource mch_res;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e4b233d..e414507 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1969,7 +1969,7 @@ i915_gem_get_seqno(struct drm_device *dev, u32 *seqno)
dev_priv->next_seqno = 1;
}
- *seqno = dev_priv->next_seqno++;
+ *seqno = dev_priv->last_seqno = dev_priv->next_seqno++;
return 0;
}
@@ -2032,6 +2032,7 @@ i915_add_request(struct intel_ring_buffer *ring,
}
trace_i915_gem_request_add(ring, request->seqno);
+ dev_priv->last_seqno = request->seqno;
ring->outstanding_lazy_request = 0;
if (!dev_priv->mm.suspended) {
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 0d03dc6..69bbe7b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -596,6 +596,13 @@ gen6_add_request(struct intel_ring_buffer *ring)
return 0;
}
+static inline bool i915_gem_has_seqno_wrapped(struct drm_device *dev,
+ u32 seqno)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ return dev_priv->last_seqno < seqno;
+}
+
/**
* intel_ring_sync - sync the waiter to the signaller on seqno
*
@@ -626,11 +633,20 @@ gen6_ring_sync(struct intel_ring_buffer *waiter,
if (ret)
return ret;
- intel_ring_emit(waiter,
- dw1 | signaller->semaphore_register[waiter->id]);
- intel_ring_emit(waiter, seqno);
- intel_ring_emit(waiter, 0);
- intel_ring_emit(waiter, MI_NOOP);
+ /* If seqno wrap happened, omit the wait with no-ops */
+ if (likely(!i915_gem_has_seqno_wrapped(waiter->dev, seqno))) {
+ intel_ring_emit(waiter,
+ dw1 |
+ signaller->semaphore_register[waiter->id]);
+ intel_ring_emit(waiter, seqno);
+ intel_ring_emit(waiter, 0);
+ intel_ring_emit(waiter, MI_NOOP);
+ } else {
+ intel_ring_emit(waiter, MI_NOOP);
+ intel_ring_emit(waiter, MI_NOOP);
+ intel_ring_emit(waiter, MI_NOOP);
+ intel_ring_emit(waiter, MI_NOOP);
+ }
intel_ring_advance(waiter);
return 0;
--
1.7.9.5
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