drm: omapdrm: Remove legacy buffer synchronization support

The omapdrm driver uses a custom API to synchronize with the SGX GPU.
This is unusable as such in the mainline kernel as the API is only
partially implemented and requires additional out-of-tree patches.
Furthermore, as no SGX driver is available in the mainline kernel, the
API can't be considered as a stable mainline API.

Now that the driver supports synchronization through fences, remove
legacy buffer synchronization support. The two userspace ioctls are
turned into no-ops to avoid breaking userspace and will be removed in
the future.

Signed-off-by: Laurent Pinchart <[e-mail]>
Reviewed-by: Tomi Valkeinen <[e-mail]>
Signed-off-by: Tomi Valkeinen <[e-mail]>

drivers/gpu/drm/omapdrm/omap_drv.c

···
 				   &args->handle);
 }
 
-static int ioctl_gem_cpu_prep(struct drm_device *dev, void *data,
-		struct drm_file *file_priv)
-{
-	struct drm_omap_gem_cpu_prep *args = data;
-	struct drm_gem_object *obj;
-	int ret;
-
-	VERB("%p:%p: handle=%d, op=%x", dev, file_priv, args->handle, args->op);
-
-	obj = drm_gem_object_lookup(file_priv, args->handle);
-	if (!obj)
-		return -ENOENT;
-
-	ret = omap_gem_op_sync(obj, args->op);
-
-	if (!ret)
-		ret = omap_gem_op_start(obj, args->op);
-
-	drm_gem_object_unreference_unlocked(obj);
-
-	return ret;
-}
-
-static int ioctl_gem_cpu_fini(struct drm_device *dev, void *data,
-		struct drm_file *file_priv)
-{
-	struct drm_omap_gem_cpu_fini *args = data;
-	struct drm_gem_object *obj;
-	int ret;
-
-	VERB("%p:%p: handle=%d", dev, file_priv, args->handle);
-
-	obj = drm_gem_object_lookup(file_priv, args->handle);
-	if (!obj)
-		return -ENOENT;
-
-	/* XXX flushy, flushy */
-	ret = 0;
-
-	if (!ret)
-		ret = omap_gem_op_finish(obj, args->op);
-
-	drm_gem_object_unreference_unlocked(obj);
-
-	return ret;
-}
-
 static int ioctl_gem_info(struct drm_device *dev, void *data,
 		struct drm_file *file_priv)
 {
···
 			  DRM_AUTH | DRM_MASTER | DRM_ROOT_ONLY),
 	DRM_IOCTL_DEF_DRV(OMAP_GEM_NEW, ioctl_gem_new,
 			  DRM_AUTH | DRM_RENDER_ALLOW),
-	DRM_IOCTL_DEF_DRV(OMAP_GEM_CPU_PREP, ioctl_gem_cpu_prep,
+	/* Deprecated, to be removed. */
+	DRM_IOCTL_DEF_DRV(OMAP_GEM_CPU_PREP, drm_noop,
 			  DRM_AUTH | DRM_RENDER_ALLOW),
-	DRM_IOCTL_DEF_DRV(OMAP_GEM_CPU_FINI, ioctl_gem_cpu_fini,
+	/* Deprecated, to be removed. */
+	DRM_IOCTL_DEF_DRV(OMAP_GEM_CPU_FINI, drm_noop,
 			  DRM_AUTH | DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(OMAP_GEM_INFO, ioctl_gem_info,
 			  DRM_AUTH | DRM_RENDER_ALLOW),

drivers/gpu/drm/omapdrm/omap_drv.h

···
 int omap_gem_mmap_obj(struct drm_gem_object *obj,
 		struct vm_area_struct *vma);
 int omap_gem_fault(struct vm_fault *vmf);
-int omap_gem_op_start(struct drm_gem_object *obj, enum omap_gem_op op);
-int omap_gem_op_finish(struct drm_gem_object *obj, enum omap_gem_op op);
-int omap_gem_op_sync(struct drm_gem_object *obj, enum omap_gem_op op);
-int omap_gem_op_async(struct drm_gem_object *obj, enum omap_gem_op op,
-		void (*fxn)(void *arg), void *arg);
 int omap_gem_roll(struct drm_gem_object *obj, uint32_t roll);
 void omap_gem_cpu_sync(struct drm_gem_object *obj, int pgoff);
 void omap_gem_dma_sync(struct drm_gem_object *obj,

drivers/gpu/drm/omapdrm/omap_gem.c

···
 	 * Virtual address, if mapped.
 	 */
 	void *vaddr;
-
-	/**
-	 * sync-object allocated on demand (if needed)
-	 *
-	 * Per-buffer sync-object for tracking pending and completed hw/dma
-	 * read and write operations.
-	 */
-	struct {
-		uint32_t write_pending;
-		uint32_t write_complete;
-		uint32_t read_pending;
-		uint32_t read_complete;
-	} *sync;
 };
 
 #define to_omap_bo(x) container_of(x, struct omap_gem_object, base)
···
 #endif
 
 /* -----------------------------------------------------------------------------
- * Buffer Synchronization
- */
-
-static DEFINE_SPINLOCK(sync_lock);
-
-struct omap_gem_sync_waiter {
-	struct list_head list;
-	struct omap_gem_object *omap_obj;
-	enum omap_gem_op op;
-	uint32_t read_target, write_target;
-	/* notify called w/ sync_lock held */
-	void (*notify)(void *arg);
-	void *arg;
-};
-
-/* list of omap_gem_sync_waiter.. the notify fxn gets called back when
- * the read and/or write target count is achieved which can call a user
- * callback (ex. to kick 3d and/or 2d), wakeup blocked task (prep for
- * cpu access), etc.
- */
-static LIST_HEAD(waiters);
-
-static inline bool is_waiting(struct omap_gem_sync_waiter *waiter)
-{
-	struct omap_gem_object *omap_obj = waiter->omap_obj;
-	if ((waiter->op & OMAP_GEM_READ) &&
-			(omap_obj->sync->write_complete < waiter->write_target))
-		return true;
-	if ((waiter->op & OMAP_GEM_WRITE) &&
-			(omap_obj->sync->read_complete < waiter->read_target))
-		return true;
-	return false;
-}
-
-/* macro for sync debug.. */
-#define SYNCDBG 0
-#define SYNC(fmt, ...) do { if (SYNCDBG)				\
-		pr_err("%s:%d: " fmt "\n", __func__, __LINE__, ##__VA_ARGS__); \
-	} while (0)
-
-
-static void sync_op_update(void)
-{
-	struct omap_gem_sync_waiter *waiter, *n;
-	list_for_each_entry_safe(waiter, n, &waiters, list) {
-		if (!is_waiting(waiter)) {
-			list_del(&waiter->list);
-			SYNC("notify: %p", waiter);
-			waiter->notify(waiter->arg);
-			kfree(waiter);
-		}
-	}
-}
-
-static inline int sync_op(struct drm_gem_object *obj,
-		enum omap_gem_op op, bool start)
-{
-	struct omap_gem_object *omap_obj = to_omap_bo(obj);
-	int ret = 0;
-
-	spin_lock(&sync_lock);
-
-	if (!omap_obj->sync) {
-		omap_obj->sync = kzalloc(sizeof(*omap_obj->sync), GFP_ATOMIC);
-		if (!omap_obj->sync) {
-			ret = -ENOMEM;
-			goto unlock;
-		}
-	}
-
-	if (start) {
-		if (op & OMAP_GEM_READ)
-			omap_obj->sync->read_pending++;
-		if (op & OMAP_GEM_WRITE)
-			omap_obj->sync->write_pending++;
-	} else {
-		if (op & OMAP_GEM_READ)
-			omap_obj->sync->read_complete++;
-		if (op & OMAP_GEM_WRITE)
-			omap_obj->sync->write_complete++;
-		sync_op_update();
-	}
-
-unlock:
-	spin_unlock(&sync_lock);
-
-	return ret;
-}
-
-/* mark the start of read and/or write operation */
-int omap_gem_op_start(struct drm_gem_object *obj, enum omap_gem_op op)
-{
-	return sync_op(obj, op, true);
-}
-
-int omap_gem_op_finish(struct drm_gem_object *obj, enum omap_gem_op op)
-{
-	return sync_op(obj, op, false);
-}
-
-static DECLARE_WAIT_QUEUE_HEAD(sync_event);
-
-static void sync_notify(void *arg)
-{
-	struct task_struct **waiter_task = arg;
-	*waiter_task = NULL;
-	wake_up_all(&sync_event);
-}
-
-int omap_gem_op_sync(struct drm_gem_object *obj, enum omap_gem_op op)
-{
-	struct omap_gem_object *omap_obj = to_omap_bo(obj);
-	int ret = 0;
-	if (omap_obj->sync) {
-		struct task_struct *waiter_task = current;
-		struct omap_gem_sync_waiter *waiter =
-				kzalloc(sizeof(*waiter), GFP_KERNEL);
-
-		if (!waiter)
-			return -ENOMEM;
-
-		waiter->omap_obj = omap_obj;
-		waiter->op = op;
-		waiter->read_target = omap_obj->sync->read_pending;
-		waiter->write_target = omap_obj->sync->write_pending;
-		waiter->notify = sync_notify;
-		waiter->arg = &waiter_task;
-
-		spin_lock(&sync_lock);
-		if (is_waiting(waiter)) {
-			SYNC("waited: %p", waiter);
-			list_add_tail(&waiter->list, &waiters);
-			spin_unlock(&sync_lock);
-			ret = wait_event_interruptible(sync_event,
-					(waiter_task == NULL));
-			spin_lock(&sync_lock);
-			if (waiter_task) {
-				SYNC("interrupted: %p", waiter);
-				/* we were interrupted */
-				list_del(&waiter->list);
-				waiter_task = NULL;
-			} else {
-				/* freed in sync_op_update() */
-				waiter = NULL;
-			}
-		}
-		spin_unlock(&sync_lock);
-		kfree(waiter);
-	}
-	return ret;
-}
-
-/* call fxn(arg), either synchronously or asynchronously if the op
- * is currently blocked..  fxn() can be called from any context
- *
- * (TODO for now fxn is called back from whichever context calls
- * omap_gem_op_finish().. but this could be better defined later
- * if needed)
- *
- * TODO more code in common w/ _sync()..
- */
-int omap_gem_op_async(struct drm_gem_object *obj, enum omap_gem_op op,
-		void (*fxn)(void *arg), void *arg)
-{
-	struct omap_gem_object *omap_obj = to_omap_bo(obj);
-	if (omap_obj->sync) {
-		struct omap_gem_sync_waiter *waiter =
-				kzalloc(sizeof(*waiter), GFP_ATOMIC);
-
-		if (!waiter)
-			return -ENOMEM;
-
-		waiter->omap_obj = omap_obj;
-		waiter->op = op;
-		waiter->read_target = omap_obj->sync->read_pending;
-		waiter->write_target = omap_obj->sync->write_pending;
-		waiter->notify = fxn;
-		waiter->arg = arg;
-
-		spin_lock(&sync_lock);
-		if (is_waiting(waiter)) {
-			SYNC("waited: %p", waiter);
-			list_add_tail(&waiter->list, &waiters);
-			spin_unlock(&sync_lock);
-			return 0;
-		}
-
-		spin_unlock(&sync_lock);
-
-		kfree(waiter);
-	}
-
-	/* no waiting.. */
-	fxn(arg);
-
-	return 0;
-}
-
-/* -----------------------------------------------------------------------------
  * Constructor & Destructor
  */
 
···
 	} else if (obj->import_attach) {
 		drm_prime_gem_destroy(obj, omap_obj->sgt);
 	}
-
-	kfree(omap_obj->sync);
 
 	drm_gem_object_release(obj);
 

include/uapi/drm/omap_drm.h

···
 #define DRM_OMAP_GET_PARAM		0x00
 #define DRM_OMAP_SET_PARAM		0x01
 #define DRM_OMAP_GEM_NEW		0x03
-#define DRM_OMAP_GEM_CPU_PREP		0x04
-#define DRM_OMAP_GEM_CPU_FINI		0x05
+#define DRM_OMAP_GEM_CPU_PREP		0x04	/* Deprecated, to be removed */
+#define DRM_OMAP_GEM_CPU_FINI		0x05	/* Deprecated, to be removed */
 #define DRM_OMAP_GEM_INFO		0x06
 #define DRM_OMAP_NUM_IOCTLS		0x07