Hi, Bob,
On Tue, 2022-05-03 at 19:13 +0000, Robert Beckett wrote:
internal buffers should be shmem backed. if a volatile buffer is requested, allow ttm to use the pool allocator to provide volatile pages as backing
Signed-off-by: Robert Beckett bob.beckett@collabora.com
drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c index 4c25d9b2f138..fdb3a1c18cb6 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;
While this is ok, I think it also needs adjustment in the i915_ttm shrink callback. If someone creates a volatile smem object which then hits the shrinker, I think we might hit asserts that it's a is_shem ttm?
In this case, the shrink callback should just i915_ttm_purge().
/Thomas