[async_tx-next PATCH v2 2/2] fsldma: Fix cookie issues

[Steven J. Magnani]

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 at digidescorp.com>
---
diff -uprN a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
--- a/drivers/dma/fsldma.c	2010-02-22 11:16:36.000000000 -0600
+++ b/drivers/dma/fsldma.c	2010-02-22 11:08:41.000000000 -0600
@@ -819,8 +819,11 @@ static void fsl_dma_update_completed_coo
 	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;
 
diff -uprN a/include/linux/dmaengine.h b/include/linux/dmaengine.h
--- a/include/linux/dmaengine.h	2010-02-22 11:18:11.000000000 -0600
+++ b/include/linux/dmaengine.h	2010-02-22 11:18:30.000000000 -0600
@@ -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	((1 << 31) - 1)
 
 #define dma_submit_error(cookie) ((cookie) < 0 ? 1 : 0)