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drm/i915: Don't emit semaphore wait if wrap happened

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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

v4: Fixed unnecessary last_seqno assigment

References: https://bugs.freedesktop.org/show_bug.cgi?id=57967
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Mika Kuoppala 2012-12-10 15:41:48 +02:00 committed by Daniel Vetter
parent 3ac1823294
commit f72b3435c1
3 changed files with 23 additions and 7 deletions
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2
drivers/gpu/drm/i915/i915_drv.h
View File

@ -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;

2
drivers/gpu/drm/i915/i915_gem.c
View File

@ -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;
}

26
drivers/gpu/drm/i915/intel_ringbuffer.c
View File

@ -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;