[PATCH 3/8] drm/i915: allow volatile buffers to use ttm pool allocator

[Robert Beckett]

Internal/volatile buffers should not be shmem backed.
If a volatile buffer is requested, allow ttm to use the pool allocator
to provide volatile pages as backing.
Fix i915_ttm_shrink to handle !is_shmem volatile buffers by purging.

Signed-off-by: Robert Beckett <bob.beckett at collabora.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 4c25d9b2f138..dff4cd68cd78 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -309,7 +309,8 @@ static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
 		page_flags |= TTM_TT_FLAG_ZERO_ALLOC;
 
 	caching = i915_ttm_select_tt_caching(obj);
-	if (i915_gem_object_is_shrinkable(obj) && caching == ttm_cached) {
+	if (i915_gem_object_is_shrinkable(obj) && caching == ttm_cached &&
+	    !i915_gem_object_is_volatile(obj)) {
 		page_flags |= TTM_TT_FLAG_EXTERNAL |
 			      TTM_TT_FLAG_EXTERNAL_MAPPABLE;
 		i915_tt->is_shmem = true;
@@ -531,9 +532,9 @@ static int i915_ttm_shrink(struct drm_i915_gem_object *obj, unsigned int flags)
 	if (!bo->ttm || bo->resource->mem_type != TTM_PL_SYSTEM)
 		return 0;
 
-	GEM_BUG_ON(!i915_tt->is_shmem);
+	GEM_BUG_ON(!i915_tt->is_shmem && obj->mm.madv != I915_MADV_DONTNEED);
 
-	if (!i915_tt->filp)
+	if (i915_tt->is_shmem && !i915_tt->filp)
 		return 0;
 
 	ret = ttm_bo_wait_ctx(bo, &ctx);
-- 
2.25.1