[PATCH] spi: nxp-fspi: Add 1us delay to make controller ready for next transaction

[Jagan Teki]

On Mon, Feb 24, 2020 at 4:52 PM Kuldeep Singh <kuldeep.singh at nxp.com> wrote:
>
> Board gets reset when performing burst read/write operations. On the
> other hand, no such behaviour is observed on small size operations.
>
> In Linux, readl_poll_timeout API already add delay of 1us which is
> skipped in U-boot. Since, NXP Flexspi U-boot driver is a ported version
> of Linux driver and U-boot poll_timeout API lacks delay functionality,
> add 1us delay so as to make controller ready for other transactions.
>
> Signed-off-by: Kuldeep Singh <kuldeep.singh at nxp.com>
> ---
>  drivers/spi/nxp_fspi.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/spi/nxp_fspi.c b/drivers/spi/nxp_fspi.c
> index 0e6c7be..9703642 100644
> --- a/drivers/spi/nxp_fspi.c
> +++ b/drivers/spi/nxp_fspi.c
> @@ -756,6 +756,7 @@ static int nxp_fspi_exec_op(struct spi_slave *slave,
>         err = fspi_readl_poll_tout(f, f->iobase + FSPI_STS0,
>                                    FSPI_STS0_ARB_IDLE, 1, POLL_TOUT, true);
>         WARN_ON(err);
> +       udelay(1);

Can you add relevant comments here, why is it for udelay(1) ?