Commit f4db23f2 authored by Thomas Hellström's avatar Thomas Hellström Committed by Matthew Auld
Browse files

drm/i915/ttm: Embed a ttm buffer object in the i915 gem object 



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: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210602083818.241793-3-thomas.hellstrom@linux.intel.com
parent d1487389

drivers/gpu/drm/i915/gem/i915_gem_object.c

+7 −0
Original line number Diff line number Diff line
@@ -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);

drivers/gpu/drm/i915/gem/i915_gem_object_types.h

+11 −1
Original line number Diff line number Diff line
@@ -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 {

	/*

	 * 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;