[PATCH 1/2] dw_dmac: check direction properly in dw_dma_cyclic_prep

[Andy Shevchenko]

dma_transfer_direction is a normal enum. It means we can't usually use the
values as bit fields. Let's adjust this check and move it above the usage of
the direction parameter.

This patch introduces helper function is_slave_direction() that will be used
later in other places of the code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/dma/dw_dmac.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index a4a5c80..771aa15 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -36,6 +36,11 @@
  * which does not support descriptor writeback.
  */
 
+static inline bool is_slave_direction(enum dma_transfer_direction direction)
+{
+	return (direction == DMA_MEM_TO_DEV) || (direction == DMA_DEV_TO_MEM);
+}
+
 static inline unsigned int dwc_get_dms(struct dw_dma_slave *slave)
 {
 	return slave ? slave->dst_master : 0;
@@ -1336,6 +1341,9 @@ struct dw_cyclic_desc *dw_dma_cyclic_prep(struct dma_chan *chan,
 
 	retval = ERR_PTR(-EINVAL);
 
+	if (unlikely(!is_slave_direction(direction)))
+		goto out_err;
+
 	if (direction == DMA_MEM_TO_DEV)
 		reg_width = __ffs(sconfig->dst_addr_width);
 	else
@@ -1350,8 +1358,6 @@ struct dw_cyclic_desc *dw_dma_cyclic_prep(struct dma_chan *chan,
 		goto out_err;
 	if (unlikely(buf_addr & ((1 << reg_width) - 1)))
 		goto out_err;
-	if (unlikely(!(direction & (DMA_MEM_TO_DEV | DMA_DEV_TO_MEM))))
-		goto out_err;
 
 	retval = ERR_PTR(-ENOMEM);
 
-- 
1.7.10.4

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