[PATCH v2] mtd: rawnand: Make sure we wait tWB before polling the STATUS reg

[Boris Brezillon]

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 in nand_soft_waitrdy().

Fixes: 8878b126df76 ("mtd: nand: add ->exec_op() implementation")
Cc: <stable at vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon at bootlin.com>
---
Changes in v2:
- Move the ndelay() to nand_soft_waitrdy() instead of having it in the
  FSMC driver
---
 drivers/mtd/nand/raw/nand_base.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 72f3a89da513..da94fcb4dd9b 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -706,12 +706,17 @@ static void nand_wait_status_ready(struct mtd_info *mtd, unsigned long timeo)
  */
 int nand_soft_waitrdy(struct nand_chip *chip, unsigned long timeout_ms)
 {
+	const struct nand_sdr_timings *timings;
 	u8 status = 0;
 	int ret;
 
 	if (!chip->exec_op)
 		return -ENOTSUPP;
 
+	/* Wait tWB before polling the STATUS reg. */
+	timings = nand_get_sdr_timings(&chip->data_interface);
+	ndelay(PSEC_TO_NSEC(sdr->tWB_max));
+
 	ret = nand_status_op(chip, NULL);
 	if (ret)
 		return ret;
-- 
2.14.1