nand: Try to align the default buffers

The NAND layer needs to use cache-aligned buffers by default. Towards this
goal. align the default buffers and their members according to the minimum
DMA alignment defined for the architecture.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
Acked-by: Scott Wood <scottwood@freescale.com>

drivers/mtd/nand/nand_base.c

@@ -2936,7 +2936,8 @@ int nand_scan_tail(struct mtd_info *mtd)
 	struct nand_chip *chip = mtd->priv;
 
 	if (!(chip->options & NAND_OWN_BUFFERS))
-		chip->buffers = kmalloc(sizeof(*chip->buffers), GFP_KERNEL);
+		chip->buffers = memalign(ARCH_DMA_MINALIGN,
+					 sizeof(*chip->buffers));
 	if (!chip->buffers)
 		return -ENOMEM;
 

include/linux/mtd/nand.h

@@ -391,9 +391,10 @@ struct nand_ecc_ctrl {
  * consecutive order.
  */
 struct nand_buffers {
-	uint8_t	ecccalc[NAND_MAX_OOBSIZE];
-	uint8_t	ecccode[NAND_MAX_OOBSIZE];
-	uint8_t databuf[NAND_MAX_PAGESIZE + NAND_MAX_OOBSIZE];
+	uint8_t	ecccalc[ALIGN(NAND_MAX_OOBSIZE, ARCH_DMA_MINALIGN)];
+	uint8_t	ecccode[ALIGN(NAND_MAX_OOBSIZE, ARCH_DMA_MINALIGN)];
+	uint8_t databuf[ALIGN(NAND_MAX_PAGESIZE + NAND_MAX_OOBSIZE,
+			      ARCH_DMA_MINALIGN)];
 };
 
 /**