On Wed, May 31, 2017 at 07:52:00PM +0100, Matthew Auld wrote:
> When inserting into a 48bit PPGTT we should the align the vma start
> address to the required page size boundary, to guarantee we use said
> page size in the gtt. If we are dealing with multiple page-sizes, we
> can't guarantee anything and just align to the largest. For soft pinning
> we don't force any alignment.
>
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_vma.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 1aba47024656..c355ccb01872 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -485,6 +485,18 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
> if (ret)
> goto err_unpin;
> } else {
> + if (i915_vm_is_48bit(vma->vm) &&
I would use end > 4G here. As that encapsulates the i915_vm_is_48bit()
test and avoids us applying the extra padding to objects that must be
tightly packed into the low 32bits.
> + obj->mm.page_sizes.sg > I915_GTT_PAGE_SIZE) {
> + unsigned int page_alignment = obj->mm.page_sizes.sg;
> +
> + /* Align to the largest and hope for the best */
> + if (!is_power_of_2(page_alignment))
> + page_alignment = BIT(fls64(page_alignment)-1);
fls64() - 1 == ilog2()
BIT(ilog2()) == roundup_pow_of_two()
linux/log2.h is your friend.
> +
> + alignment = max_t(typeof(alignment), alignment,
> + page_alignment);
Make page_alignment be u64 and be happy.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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