dmaengine: dma_sync_wait and dma_find_channel undefined

dma_sync_wait and dma_find_channel are declared regardless of whether
CONFIG_DMA_ENGINE is enabled, but calling the function without
CONFIG_DMA_ENGINE enabled results "undefined reference" errors.

To get around this, declare dma_sync_wait and dma_find_channel as inline
functions if CONFIG_DMA_ENGINE is undefined.

Signed-off-by: Jon Mason <>
Signed-off-by: Dan Williams <>
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index b3ba7e4..0c72b89 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -961,8 +961,9 @@
-enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie);
+struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type);
+enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie);
 enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
 void dma_issue_pending_all(void);
 struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
@@ -970,6 +971,14 @@
 struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name);
 void dma_release_channel(struct dma_chan *chan);
+static inline struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
+	return NULL;
+static inline enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie)
+	return DMA_SUCCESS;
 static inline enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
 	return DMA_SUCCESS;
@@ -997,7 +1006,6 @@
 int dma_async_device_register(struct dma_device *device);
 void dma_async_device_unregister(struct dma_device *device);
 void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
-struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type);
 struct dma_chan *net_dma_find_channel(void);
 #define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
 #define dma_request_slave_channel_compat(mask, x, y, dev, name) \