Patchwork [async_tx-next,2/2] fsldma: Fix cookie issues

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Submitter Steven J. Magnani
Date Feb. 22, 2010, 5:40 p.m.
Message ID <1266860439-17352-1-git-send-email-steve@digidescorp.com>
Download mbox | patch
Permalink /patch/46033/
State Superseded
Delegated to: Kumar Gala
Headers show

Comments

Steven J. Magnani - Feb. 22, 2010, 5:40 p.m.
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>
---
Ira Snyder - Feb. 25, 2010, 7:25 p.m.
On Mon, Feb 22, 2010 at 09:26:13PM +0100, Guennadi Liakhovetski wrote:
> On Mon, 22 Feb 2010, Steven J. Magnani wrote:
> 
> > 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	2147483647
> 
> Taking into account, that dma_cookie_t is 32 bits:
> 
> +#define DMA_MAX_COOKIE		((1 << 31) - 1)
> 

Steven,

After you take Guennadi's comment into acount, the rest of the patch
looks good. I'm sure I've never rolled the cookie around during testing.

Ira

Patch

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	2147483647
 
 #define dma_submit_error(cookie) ((cookie) < 0 ? 1 : 0)