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[PATCH 4.6 05/96] dmaengine: at_xdmac: align descriptors on 64 bits

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  [PATCH 4.6 05/96] dmaengine: at_xdmac: align descriptors on 64 bits Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-08 21:20 +0200

#1458037 — [PATCH 4.6 05/96] dmaengine: at_xdmac: align descriptors on 64 bits

4.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ludovic Desroches <ludovic.desroches@atmel.com>

commit 4a9723e8df68cfce4048517ee32e37f78854b6fb upstream.

Having descriptors aligned on 64 bits allows update CNDA and CUBC in an
atomic way.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel
eXtended DMA Controller driver")
Reviewed-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/dma/at_xdmac.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -242,7 +242,7 @@ struct at_xdmac_lld {
 	u32		mbr_dus;	/* Destination Microblock Stride Register */
 };
 
-
+/* 64-bit alignment needed to update CNDA and CUBC registers in an atomic way. */
 struct at_xdmac_desc {
 	struct at_xdmac_lld		lld;
 	enum dma_transfer_direction	direction;
@@ -253,7 +253,7 @@ struct at_xdmac_desc {
 	unsigned int			xfer_size;
 	struct list_head		descs_list;
 	struct list_head		xfer_node;
-};
+} __aligned(sizeof(u64));
 
 static inline void __iomem *at_xdmac_chan_reg_base(struct at_xdmac *atxdmac, unsigned int chan_nb)
 {

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