[MTD] [NAND] fsl_elbc_nand: workaround for hangs during nand write

Using current driver elbc sometimes hangs during nand write. Reading back
last byte helps though (thanks to Scott Wood for the idea).
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/nand/fsl_elbc_nand.c

@@ -481,7 +481,7 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
 	struct fsl_elbc_ctrl *ctrl = priv->ctrl;
 	unsigned int bufsize = mtd->writesize + mtd->oobsize;
 
-	if (len < 0) {
+	if (len <= 0) {
 		dev_err(ctrl->dev, "write_buf of %d bytes", len);
 		ctrl->status = 0;
 		return;
@@ -496,6 +496,15 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
 	}
 
 	memcpy_toio(&ctrl->addr[ctrl->index], buf, len);
+	/*
+	 * This is workaround for the weird elbc hangs during nand write,
+	 * Scott Wood says: "...perhaps difference in how long it takes a
+	 * write to make it through the localbus compared to a write to IMMR
+	 * is causing problems, and sync isn't helping for some reason."
+	 * Reading back the last byte helps though.
+	 */
+	in_8(&ctrl->addr[ctrl->index] + len - 1);
+
 	ctrl->index += len;
 }