Extract all this logic into a new helper function
semaphore_wait_to_signaller_ring because:
- The current code has way too much magic.
- The current code doesn't look at bi16, which encodes VECS signallers
on HSW. Those are just added after the fact, so can't be encoded in
a neat formula.
- It blindly trust the hardware for the dev_priv->ring array
derefence, which given that we have a gpu hang at hand is scary. The
current logic can't blow up since it limits its value range
sufficiently, but that's a bit too tricky to rely on in my opinion.
Especially when we start to add bdw support.
- I'm not a big fan of the explicit ring->semaphore_register list, but
I think it's more robust to use the same mapping both when
constructing the semaphore commands and when decoding them.
- Finally add a FIXME comment about lack of broadwell support here,
like in the earlier ipehr semaphore cmd detection function.
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Cc: Ben Widawsky <ben@xxxxxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/gpu/drm/i915/i915_irq.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 0f3a6d791502..98f95ca77246 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2543,6 +2543,39 @@ ipehr_is_semaphore_wait(struct drm_device *dev, u32 ipehr)
}
static struct intel_ring_buffer *
+semaphore_wait_to_signaller_ring(struct intel_ring_buffer *ring, u32 ipehr)
+{
+ struct drm_i915_private *dev_priv = ring->dev->dev_private;
+ struct intel_ring_buffer *signaller;
+ int i;
+
+ if (INTEL_INFO(dev_priv->dev)->gen >= 8) {
+ /*
+ * FIXME: gen8 semaphore support - currently we don't emit
+ * semaphores on bdw anyway, but this needs to be addressed when
+ * we merge that code.
+ */
+ return NULL;
+ } else {
+ u32 sync_bits = ipehr & MI_SEMAPHORE_SYNC_MASK;
+
+ for_each_ring(signaller, dev_priv, i) {
+ if(ring == signaller)
+ continue;
+
+ if (sync_bits ==
+ signaller->semaphore_register[ring->id])
+ return signaller;
+ }
+ }
+
+ DRM_ERROR("No signaller ring found for ring %i, ipehr 0x%08x\n",
+ ring->id, ipehr);
+
+ return NULL;
+}
+
+static struct intel_ring_buffer *
semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno)
{
struct drm_i915_private *dev_priv = ring->dev->dev_private;
@@ -2582,7 +2615,7 @@ semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno)
return NULL;
*seqno = ioread32(ring->virtual_start + head + 4) + 1;
- return &dev_priv->ring[(ring->id + (((ipehr >> 17) & 1) + 1)) % 3];
+ return semaphore_wait_to_signaller_ring(ring, ipehr);
}
static int semaphore_passed(struct intel_ring_buffer *ring)
--
1.8.1.4
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