fsldma: Fix cookie issues

fsl_dma_update_completed_cookie() appears to calculate the last completed
cookie incorrectly in the corner case where DMA on cookie 1 is in progress
just following a cookie wrap.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Acked-by: Ira W. Snyder <iws@ovro.caltech.edu>
[dan.j.williams@intel.com: fix an integer overflow warning with INT_MAX]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/fsldma.c

@@ -819,8 +819,11 @@ static void fsl_dma_update_completed_cookie(struct fsldma_chan *chan)
 	desc = to_fsl_desc(chan->ld_running.prev);
 	if (dma_is_idle(chan))
 		cookie = desc->async_tx.cookie;
-	else
+	else {
 		cookie = desc->async_tx.cookie - 1;
+		if (unlikely(cookie < DMA_MIN_COOKIE))
+			cookie = DMA_MAX_COOKIE;
+	}
 
 	chan->completed_cookie = cookie;
 

include/linux/dmaengine.h

@@ -31,6 +31,8 @@
  * if dma_cookie_t is >0 it's a DMA request cookie, <0 it's an error code
  */
 typedef s32 dma_cookie_t;
+#define DMA_MIN_COOKIE	1
+#define DMA_MAX_COOKIE	INT_MAX
 
 #define dma_submit_error(cookie) ((cookie) < 0 ? 1 : 0)