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>

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index 6541ebf..bbb4be5 100644 (file)
--- a/drivers/dma/fsldma.c
+++ b/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;
 

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 7878498..4d8d619 100644 (file)
--- a/include/linux/dmaengine.h
+++ b/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)