Embed a struct ttm_buffer_object into the i915 gem object, making sure
we alias the gem object part. It's a bit unfortunate that the
struct ttm_buffer_ojbect embeds a gem object since we otherwise could
make the TTM part private to the TTM backend, and use the usual
i915 gem object for the other backends.
To make this a bit more storage efficient for the other backends,
we'd have to use a pointer for the gem object which would require
a lot of changes in the driver. We postpone that for later.
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210602083818.241793-3-thomas.hellstrom@linux.intel.com
const struct drm_i915_gem_object_ops *ops,
struct lock_class_key *key, unsigned flags)
{
+ /*
+ * A gem object is embedded both in a struct ttm_buffer_object :/ and
+ * in a drm_i915_gem_object. Make sure they are aliased.
+ */
+ BUILD_BUG_ON(offsetof(typeof(*obj), base) !=
+ offsetof(typeof(*obj), __do_not_access.base));
+
spin_lock_init(&obj->vma.lock);
INIT_LIST_HEAD(&obj->vma.list);
#include <linux/mmu_notifier.h>
#include <drm/drm_gem.h>
+#include <drm/ttm/ttm_bo_api.h>
#include <uapi/drm/i915_drm.h>
#include "i915_active.h"
};
struct drm_i915_gem_object {
- struct drm_gem_object base;
+ /*
+ * We might have reason to revisit the below since it wastes
+ * a lot of space for non-ttm gem objects.
+ * In any case, always use the accessors for the ttm_buffer_object
+ * when accessing it.
+ */
+ union {
+ struct drm_gem_object base;
+ struct ttm_buffer_object __do_not_access;
+ };
const struct drm_i915_gem_object_ops *ops;