drm/vmwgfx: Make sure we unpin no longer needed buffers

We were not correctly unpinning no longer needed buffers. In particular
vmw_buffer_object, which is internally often pinned on creation wasn't
unpinned on destruction and none of the internal MOB buffers were
unpinned before being put back. Technically this existed for a
long time but commit 57fcd55 ("drm/ttm: Warn on pinning without
holding a reference") introduced a WARN_ON which was filling up the
kernel logs rather quickly.

Quite frankly internal usage of vmw_buffer_object and in general
pinning needs to be refactored in vmwgfx but for now this makes
it work.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Fixes: 57fcd55 ("drm/ttm: Warn on pinning without holding a reference")
Link: https://patchwork.freedesktop.org/patch/414984/?series=86052&rev=1
Cc: Huang Rui <ray.huang@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: dri-devel@lists.freedesktop.org

Author: zackr

drivers/gpu/drm/vmwgfx/vmwgfx_drv.h

@@ -1525,6 +1525,8 @@ static inline void vmw_bo_unreference(struct vmw_buffer_object **buf)
 
 	*buf = NULL;
 	if (tmp_buf != NULL) {
+		if (tmp_buf->base.pin_count > 0)
+			ttm_bo_unpin(&tmp_buf->base);
 		ttm_bo_put(&tmp_buf->base);
 	}
 }

drivers/gpu/drm/vmwgfx/vmwgfx_mob.c

@@ -277,6 +277,7 @@ static int vmw_otable_batch_setup(struct vmw_private *dev_priv,
 						 &batch->otables[i]);
 	}
 
+	ttm_bo_unpin(batch->otable_bo);
 	ttm_bo_put(batch->otable_bo);
 	batch->otable_bo = NULL;
 	return ret;
@@ -342,6 +343,7 @@ static void vmw_otable_batch_takedown(struct vmw_private *dev_priv,
 	vmw_bo_fence_single(bo, NULL);
 	ttm_bo_unreserve(bo);
 
+	ttm_bo_unpin(batch->otable_bo);
 	ttm_bo_put(batch->otable_bo);
 	batch->otable_bo = NULL;
 }
@@ -528,6 +530,7 @@ static void vmw_mob_pt_setup(struct vmw_mob *mob,
 void vmw_mob_destroy(struct vmw_mob *mob)
 {
 	if (mob->pt_bo) {
+		ttm_bo_unpin(mob->pt_bo);
 		ttm_bo_put(mob->pt_bo);
 		mob->pt_bo = NULL;
 	}
@@ -643,6 +646,7 @@ int vmw_mob_bind(struct vmw_private *dev_priv,
 out_no_cmd_space:
 	vmw_fifo_resource_dec(dev_priv);
 	if (pt_set_up) {
+		ttm_bo_unpin(mob->pt_bo);
 		ttm_bo_put(mob->pt_bo);
 		mob->pt_bo = NULL;
 	}