drm/ttm: Remove cpu_writers related code

[Maarten Lankhorst <maarten.lankhorst@canonical.com>]

Nobody uses it, so might as well simplify the code some.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
---
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 36f4b28..ddfe393 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -141,7 +141,6 @@ static void ttm_bo_release_list(struct kref *list_kref)
 
 	BUG_ON(atomic_read(&bo->list_kref.refcount));
 	BUG_ON(atomic_read(&bo->kref.refcount));
-	BUG_ON(atomic_read(&bo->cpu_writers));
 	BUG_ON(bo->sync_obj != NULL);
 	BUG_ON(bo->mem.mm_node != NULL);
 	BUG_ON(!list_empty(&bo->lru));
@@ -1050,16 +1049,6 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 }
 EXPORT_SYMBOL(ttm_bo_mem_space);
 
-int ttm_bo_wait_cpu(struct ttm_buffer_object *bo, bool no_wait)
-{
-	if ((atomic_read(&bo->cpu_writers) > 0) && no_wait)
-		return -EBUSY;
-
-	return wait_event_interruptible(bo->event_queue,
-					atomic_read(&bo->cpu_writers) == 0);
-}
-EXPORT_SYMBOL(ttm_bo_wait_cpu);
-
 int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
 			struct ttm_placement *placement,
 			bool interruptible, bool no_wait_reserve,
@@ -1211,7 +1200,6 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
 
 	kref_init(&bo->kref);
 	kref_init(&bo->list_kref);
-	atomic_set(&bo->cpu_writers, 0);
 	atomic_set(&bo->reserved, 1);
 	init_waitqueue_head(&bo->event_queue);
 	INIT_LIST_HEAD(&bo->lru);
@@ -1769,35 +1757,6 @@ int ttm_bo_wait(struct ttm_buffer_object *bo,
 }
 EXPORT_SYMBOL(ttm_bo_wait);
 
-int ttm_bo_synccpu_write_grab(struct ttm_buffer_object *bo, bool no_wait)
-{
-	struct ttm_bo_device *bdev = bo->bdev;
-	int ret = 0;
-
-	/*
-	 * Using ttm_bo_reserve makes sure the lru lists are updated.
-	 */
-
-	ret = ttm_bo_reserve(bo, true, no_wait, false, 0);
-	if (unlikely(ret != 0))
-		return ret;
-	spin_lock(&bdev->fence_lock);
-	ret = ttm_bo_wait(bo, false, true, no_wait);
-	spin_unlock(&bdev->fence_lock);
-	if (likely(ret == 0))
-		atomic_inc(&bo->cpu_writers);
-	ttm_bo_unreserve(bo);
-	return ret;
-}
-EXPORT_SYMBOL(ttm_bo_synccpu_write_grab);
-
-void ttm_bo_synccpu_write_release(struct ttm_buffer_object *bo)
-{
-	if (atomic_dec_and_test(&bo->cpu_writers))
-		wake_up_all(&bo->event_queue);
-}
-EXPORT_SYMBOL(ttm_bo_synccpu_write_release);
-
 /**
  * A buffer object shrink method that tries to swap out the first
  * buffer object on the bo_global::swap_lru list.
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index f8187ea..626a3f6 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -439,7 +439,6 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 	INIT_LIST_HEAD(&fbo->swap);
 	INIT_LIST_HEAD(&fbo->io_reserve_lru);
 	fbo->vm_node = NULL;
-	atomic_set(&fbo->cpu_writers, 0);
 
 	fbo->sync_obj = driver->sync_obj_ref(bo->sync_obj);
 	kref_init(&fbo->list_kref);
diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
index 3832fe1..3f48a46 100644
--- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
+++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
@@ -181,15 +181,6 @@ retry_this_bo:
 		}
 
 		entry->reserved = true;
-		if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
-			ttm_eu_backoff_reservation_locked(list);
-			spin_unlock(&glob->lru_lock);
-			ttm_eu_list_ref_sub(list);
-			ret = ttm_bo_wait_cpu(bo, false);
-			if (ret)
-				return ret;
-			goto retry;
-		}
 	}
 
 	ttm_eu_del_from_lru_locked(list);
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index e15f2a8..0853162 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -225,12 +225,6 @@ struct ttm_buffer_object {
 	bool evicted;
 
 	/**
-	 * Members protected by the bo::reserved lock only when written to.
-	 */
-
-	atomic_t cpu_writers;
-
-	/**
 	 * Members protected by the bdev::lru_lock.
 	 */
 
@@ -423,31 +417,6 @@ extern void ttm_bo_unlock_delayed_workqueue(struct ttm_bo_device *bdev,
 					    int resched);
 
 /**
- * ttm_bo_synccpu_write_grab
- *
- * @bo: The buffer object:
- * @no_wait: Return immediately if buffer is busy.
- *
- * Synchronizes a buffer object for CPU RW access. This means
- * blocking command submission that affects the buffer and
- * waiting for buffer idle. This lock is recursive.
- * Returns
- * -EBUSY if the buffer is busy and no_wait is true.
- * -ERESTARTSYS if interrupted by a signal.
- */
-extern int
-ttm_bo_synccpu_write_grab(struct ttm_buffer_object *bo, bool no_wait);
-
-/**
- * ttm_bo_synccpu_write_release:
- *
- * @bo : The buffer object.
- *
- * Releases a synccpu lock.
- */
-extern void ttm_bo_synccpu_write_release(struct ttm_buffer_object *bo);
-
-/**
  * ttm_bo_acc_size
  *
  * @bdev: Pointer to a ttm_bo_device struct.
@@ -513,7 +482,7 @@ extern int ttm_bo_init(struct ttm_bo_device *bdev,
 			void (*destroy) (struct ttm_buffer_object *));
 
 /**
- * ttm_bo_synccpu_object_init
+ * ttm_bo_create
  *
  * @bdev: Pointer to a ttm_bo_device struct.
  * @bo: Pointer to a ttm_buffer_object to be initialized.
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index a05f1b5..75d5da7 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -732,20 +732,6 @@ extern void ttm_bo_mem_put(struct ttm_buffer_object *bo,
 extern void ttm_bo_mem_put_locked(struct ttm_buffer_object *bo,
 				  struct ttm_mem_reg *mem);
 
-/**
- * ttm_bo_wait_for_cpu
- *
- * @bo: Pointer to a struct ttm_buffer_object.
- * @no_wait: Don't sleep while waiting.
- *
- * Wait until a buffer object is no longer sync'ed for CPU access.
- * Returns:
- * -EBUSY: Buffer object was sync'ed for CPU access. (only if no_wait == 1).
- * -ERESTARTSYS: An interruptible sleep was interrupted by a signal.
- */
-
-extern int ttm_bo_wait_cpu(struct ttm_buffer_object *bo, bool no_wait);
-
 extern void ttm_bo_global_release(struct drm_global_reference *ref);
 extern int ttm_bo_global_init(struct drm_global_reference *ref);