| Message ID | 20180503093659.23668-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Quoting Chris Wilson (2018-05-03 10:36:59) > Investigating the coherency issue on gdg (ye olde gen2), in particular > the failure in gem_set_tiling_vs_pwrite, it appears that gem_write() > followed by gem_read() fails. That is a write through the GTT write > domain, followed by a read through the CPU domain. Since we have > disabled clflush on the machine, we know it is moving the whole object > between domains and issuing wbinvd. Still this does not appear to be > enough, so let's resort to a chipset-flush which includes poking around > in magic registers. > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > --- > drivers/gpu/drm/i915/i915_gem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 484354f25f98..e97aacc335f2 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -793,7 +793,7 @@ void i915_gem_flush_ggtt_writes(struct drm_i915_private *dev_priv) > * that was!). > */ > > - wmb(); > + i915_gem_chipset_flush(dev_priv); > > intel_runtime_pm_get(dev_priv); > spin_lock_irq(&dev_priv->uncore.lock); I should mention that we should do a better job of tracking when we need such a global hammer -- we almost have the infrastructure in place as we do track GGTT writes on a vma, we just don't keep them in a global list. -Chris
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 484354f25f98..e97aacc335f2 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -793,7 +793,7 @@ void i915_gem_flush_ggtt_writes(struct drm_i915_private *dev_priv) * that was!). */ - wmb(); + i915_gem_chipset_flush(dev_priv); intel_runtime_pm_get(dev_priv); spin_lock_irq(&dev_priv->uncore.lock);
Investigating the coherency issue on gdg (ye olde gen2), in particular the failure in gem_set_tiling_vs_pwrite, it appears that gem_write() followed by gem_read() fails. That is a write through the GTT write domain, followed by a read through the CPU domain. Since we have disabled clflush on the machine, we know it is moving the whole object between domains and issuing wbinvd. Still this does not appear to be enough, so let's resort to a chipset-flush which includes poking around in magic registers. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> --- drivers/gpu/drm/i915/i915_gem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)