Op 18-05-2021 om 10:26 schreef Thomas Hellström:
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
drivers/gpu/drm/i915/gem/i915_gem_object.c | 7 +++++++ drivers/gpu/drm/i915/gem/i915_gem_object_types.h | 12 +++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c index abadf0994ad0..c8953e3f5c70 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c @@ -62,6 +62,13 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj, 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);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h index dbd7fffe956e..98f69d8fd37d 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h @@ -10,6 +10,7 @@ #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" @@ -99,7 +100,16 @@ struct i915_gem_object_page_iter { };
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;
Considering Dave did roughly the same in his patches, I don't think there's a better way to do this.
Although he just wrapped base.base using sizes. This works too. It probably needs someone else's r-b too, to ensure this is allowed.
Acked-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com