async_tx: make async_tx channel switching opt-in

The majority of drivers in drivers/dma/ will never establish cross
channel operation chains and do not need the extra overhead in struct
dma_async_tx_descriptor.  Make channel switching opt-in by default.

Cc: Anatolij Gustschin <agust@denx.de>
Cc: Ira Snyder <iws@ovro.caltech.edu>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: Saeed Bishara <saeed@marvell.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 3934ebdd85c2..9d8688b92d8b 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -321,14 +321,14 @@ struct dma_async_tx_descriptor {
         dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx);
         dma_async_tx_callback callback;
         void *callback_param;
-#ifndef CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH
+#ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
         struct dma_async_tx_descriptor *next;
         struct dma_async_tx_descriptor *parent;
         spinlock_t lock;
 #endif
 };
 
-#ifdef CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH
+#ifndef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
 static inline void txd_lock(struct dma_async_tx_descriptor *txd)
 {
 }
@@ -656,11 +656,11 @@ static inline void net_dmaengine_put(void)
 #ifdef CONFIG_ASYNC_TX_DMA
 #define async_dmaengine_get()   dmaengine_get()
 #define async_dmaengine_put()   dmaengine_put()
-#ifdef CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH
+#ifndef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
 #define async_dma_find_channel(type) dma_find_channel(DMA_ASYNC_TX)
 #else
 #define async_dma_find_channel(type) dma_find_channel(type)
-#endif /* CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH */
+#endif /* CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH */
 #else
 static inline void async_dmaengine_get(void)
 {