Chris Wilson <ch...@chris-wilson.co.uk> writes:
> Across the many users of the GGTT vma (internal objects, mmapings,
> display etc), we may end up with conflicting requirements for the
> placement. Currently, we try to resolve the conflict by unbinding the
> vma and rebinding it to match the new constraints; over time we will end
> up with a GGTT that matches the most strict constraints over all
> concurrent users. However, this causes a problem if the vma is currently
> in use as we must wait until it is idle before moving it. But there is
> no restriction on the number of views we may (apart from the limited
we may...have/impose?
-Mika
> size of the GGTT itself), and so if the active vma does not meet our
> requirements, try and build a new one!
>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 44 +++++++++++++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 0cbcb9f54e7d..29a4594ddef2 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -933,6 +933,44 @@ void i915_gem_runtime_suspend(struct drm_i915_private
> *i915)
> }
> }
>
> +static bool
> +discard_ggtt_vma(struct i915_vma *vma, const struct i915_ggtt_view *view)
> +{
> + const struct i915_ggtt_view discard = {
> + .type = I915_GGTT_VIEW_PARTIAL,
> + };
> + struct drm_i915_gem_object *obj = vma->obj;
> +
> + spin_lock(&obj->vma.lock);
> + if (i915_vma_compare(vma, vma->vm, &discard)) {
> + struct rb_node *rb, **p;
> +
> + rb_erase(&vma->obj_node, &obj->vma.tree);
> + vma->ggtt_view = discard;
> +
> + rb = NULL;
> + p = &obj->vma.tree.rb_node;
> + while (*p) {
> + struct i915_vma *pos;
> + long cmp;
> +
> + rb = *p;
> + pos = rb_entry(rb, struct i915_vma, obj_node);
> +
> + cmp = i915_vma_compare(pos, vma->vm, &discard);
> + if (cmp < 0)
> + p = &rb->rb_right;
> + else
> + p = &rb->rb_left;
> + }
> + rb_link_node(&vma->obj_node, rb, p);
> + rb_insert_color(&vma->obj_node, &obj->vma.tree);
> + }
> + spin_unlock(&obj->vma.lock);
> +
> + return i915_vma_compare(vma, vma->vm, view);
> +}
> +
> struct i915_vma *
> i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
> const struct i915_ggtt_view *view,
> @@ -979,6 +1017,7 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
> return ERR_PTR(-ENOSPC);
> }
>
> +new_vma:
> vma = i915_vma_instance(obj, &ggtt->vm, view);
> if (IS_ERR(vma))
> return vma;
> @@ -993,6 +1032,11 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object
> *obj,
> return ERR_PTR(-ENOSPC);
> }
>
> + if (i915_vma_is_pinned(vma) || i915_vma_is_active(vma)) {
> + if (discard_ggtt_vma(vma, view))
> + goto new_vma;
> + }
> +
> ret = i915_vma_unbind(vma);
> if (ret)
> return ERR_PTR(ret);
> --
> 2.20.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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