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. Using the testcases, we have very deterministic testing which given how difficult it would be to debug an issue (GPU hang) stemming from a wraparound using pure postmortem analysis I see no value in forcing a wrap during boot. Advancing the global next_seqno after a GPU reset is equally pointless. References? https://bugs.freedesktop.org/show_bug.cgi?id=95023 Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/i915_gem.c | 14 -------------- 1 file changed, 14 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index e3dbcf6178bc..8c8b44883657 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -4847,12 +4847,6 @@ 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); - out: intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL); return ret; @@ -4997,14 +4991,6 @@ i915_gem_load_init(struct drm_device *dev) dev_priv->relative_constants_mode = I915_EXEC_CONSTANTS_REL_GENERAL; - /* - * 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); - INIT_LIST_HEAD(&dev_priv->mm.fence_list); init_waitqueue_head(&dev_priv->pending_flip_queue); -- 2.8.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
