We have testcases to ensure that seqno wraparound works fine, so we can
forgo forcing everyone to encounter seqno wraparound during early
uptime. seqno wraparound incurs a full GPU stall so not forcing it
will eliminate one jitter from the early system.

Advancing the global next_seqno after a GPU reset is equally pointless.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c | 16 +---------------
 1 file changed, 1 insertion(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0cfdd971e8d7..2c3e36e19cb0 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4774,14 +4774,6 @@ i915_gem_init_hw(struct drm_device *dev)
                }
        }
 
-       /*
-        * Increment the next seqno by 0x100 so we have a visible break
-        * on re-initialisation
-        */
-       ret = i915_gem_set_seqno(dev, dev_priv->next_seqno+0x100);
-       if (ret)
-               goto out;
-
        /* Now it is safe to go back round and do everything else: */
        for_each_ring(ring, dev_priv, i) {
                struct drm_i915_gem_request *req;
@@ -4969,13 +4961,7 @@ i915_gem_load(struct drm_device *dev)
                dev_priv->num_fence_regs =
                                I915_READ(vgtif_reg(avail_rs.fence_num));
 
-       /*
-        * Set initial sequence number for requests.
-        * Using this number allows the wraparound to happen early,
-        * catching any obvious problems.
-        */
-       dev_priv->next_seqno = ((u32)~0 - 0x1100);
-       dev_priv->last_seqno = ((u32)~0 - 0x1101);
+       dev_priv->next_seqno = 1;
 
        /* Initialize fence registers to zero */
        INIT_LIST_HEAD(&dev_priv->mm.fence_list);
-- 
2.6.2

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