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>
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 235153c..8bcb15f 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -706,7 +706,7 @@
BUG_ON(!device->dev);
/* note: this only matters in the
- * CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH=y case
+ * CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH=n case
*/
if (device_has_all_tx_types(device))
dma_cap_set(DMA_ASYNC_TX, device->cap_mask);
@@ -980,7 +980,7 @@
struct dma_chan *chan)
{
tx->chan = chan;
- #ifndef CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH
+ #ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
spin_lock_init(&tx->lock);
#endif
}