mtd: nand: sunxi: Improve sunxi_nfc_cmd_ctrl()

We only need to call sunxi_nfc_wait_cmd_fifo_empty() if we want to send
a new command. Move the sunxi_nfc_wait_cmd_fifo_empty() call to right
place to avoid extra register reads.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/sunxi_nand.c

@@ -604,10 +604,6 @@ static void sunxi_nfc_cmd_ctrl(struct mtd_info *mtd, int dat,
 	struct sunxi_nfc *nfc = to_sunxi_nfc(sunxi_nand->nand.controller);
 	int ret;
 
-	ret = sunxi_nfc_wait_cmd_fifo_empty(nfc);
-	if (ret)
-		return;
-
 	if (dat == NAND_CMD_NONE && (ctrl & NAND_NCE) &&
 	    !(ctrl & (NAND_CLE | NAND_ALE))) {
 		u32 cmd = 0;
@@ -637,6 +633,10 @@ static void sunxi_nfc_cmd_ctrl(struct mtd_info *mtd, int dat,
 			writel(sunxi_nand->addr[1],
 			       nfc->regs + NFC_REG_ADDR_HIGH);
 
+		ret = sunxi_nfc_wait_cmd_fifo_empty(nfc);
+		if (ret)
+			return;
+
 		writel(cmd, nfc->regs + NFC_REG_CMD);
 		sunxi_nand->addr[0] = 0;
 		sunxi_nand->addr[1] = 0;