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

[Boris Brezillon]

On Fri,  4 May 2018 21:24:31 +0200
Boris Brezillon <boris.brezillon at bootlin.com> wrote:

> 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));

			    ^ timings->tWB_max

And for those who wonder, yes, I compiled the code, but it seems I
forgot to amend the commit after fixing the bug locally :-).

> +
>  	ret = nand_status_op(chip, NULL);
>  	if (ret)
>  		return ret;