| Message ID | 20180610194325.13467-6-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Quoting Chris Wilson (2018-06-10 22:43:13) > When we update the gen6 ppgtt page directories, we do so by writing the > new address into a reserved slot in the GGTT. It appears that when the > GPU reads that entry from the gsm, it uses its small cache and that we > need to invalidate that cache after writing. We don't see an issue > currently as we prefill the ppgtt page directories on creation; and only > create the single aliasing_ppgtt long before we start using the GGTT > (and so before the cache mayhave a conflicting entry). "may have" > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> > Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> > Cc: Matthew Auld <matthew.william.auld@gmail.com> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Regards, Joonas
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c index 9966845a7f22..63569bd71fef 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -1693,8 +1693,8 @@ static inline void gen6_write_pde(const struct i915_hw_ppgtt *ppgtt, const struct i915_page_table *pt) { /* Caller needs to make sure the write completes if necessary */ - writel_relaxed(GEN6_PDE_ADDR_ENCODE(px_dma(pt)) | GEN6_PDE_VALID, - ppgtt->pd_addr + pde); + iowrite32(GEN6_PDE_ADDR_ENCODE(px_dma(pt)) | GEN6_PDE_VALID, + ppgtt->pd_addr + pde); } /* Write all the page tables found in the ppgtt structure to incrementing page @@ -1709,7 +1709,7 @@ static void gen6_write_page_range(struct i915_hw_ppgtt *ppgtt, gen6_write_pde(ppgtt, pde, pt); mark_tlbs_dirty(ppgtt); - wmb(); + gen6_ggtt_invalidate(ppgtt->vm.i915); } static void gen8_ppgtt_enable(struct drm_i915_private *dev_priv) @@ -1864,7 +1864,7 @@ static int gen6_alloc_va_range(struct i915_address_space *vm, if (flush) { mark_tlbs_dirty(ppgtt); - wmb(); + gen6_ggtt_invalidate(ppgtt->vm.i915); } return 0;
When we update the gen6 ppgtt page directories, we do so by writing the new address into a reserved slot in the GGTT. It appears that when the GPU reads that entry from the gsm, it uses its small cache and that we need to invalidate that cache after writing. We don't see an issue currently as we prefill the ppgtt page directories on creation; and only create the single aliasing_ppgtt long before we start using the GGTT (and so before the cache mayhave a conflicting entry). Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: Matthew Auld <matthew.william.auld@gmail.com> --- drivers/gpu/drm/i915/i915_gem_gtt.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)