[PATCH] mtd: rawnand: fsmc: Make sure we wait tWB before polling the STATUS reg

[Boris Brezillon <boris.brezillon@bootlin.com>]

NAND chips require a bit of time to take the NAND operation into account
and set the BUSY bit in the STATUS reg. Make sure we don't poll the
STATUS reg too early.

Fixes: 4da712e70294 ("mtd: nand: fsmc: use ->exec_op()")
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
 drivers/mtd/nand/raw/fsmc_nand.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/mtd/nand/raw/fsmc_nand.c b/drivers/mtd/nand/raw/fsmc_nand.c
index 28c48dcc514e..0960665858b7 100644
--- a/drivers/mtd/nand/raw/fsmc_nand.c
+++ b/drivers/mtd/nand/raw/fsmc_nand.c
@@ -18,6 +18,7 @@
 
 #include <linux/clk.h>
 #include <linux/completion.h>
+#include <linux/delay.h>
 #include <linux/dmaengine.h>
 #include <linux/dma-direction.h>
 #include <linux/dma-mapping.h>
@@ -695,6 +696,13 @@ static int fsmc_exec_op(struct nand_chip *chip, const struct nand_operation *op,
 			pr_debug("  ->WAITRDY  [max %d ms]\n",
 				 instr->ctx.waitrdy.timeout_ms);
 
+			/*
+			 * Make sure we wait tWB before polling the STATUS
+			 * register.
+			 */
+			if (op_id && op->instrs[op_id - 1].delay_ns)
+				ndelay(op->instrs[op_id - 1].delay_ns);
+
 			ret = nand_soft_waitrdy(chip,
 						instr->ctx.waitrdy.timeout_ms);
 			break;
-- 
2.14.1