Re: [PATCH u-boot-marvell 09/14] tools: kwboot: Force BootROM to flush input queue after boot pattern

Stefan Roese
2022-01-26T15:45:34Z

On 1/25/22 18:13, Marek Behún wrote:
> From: Pali Rohár <pali@kernel.org>
>
> Force the BootROM to flush its input queue after sending boot pattern.
>
> This ensures that after function kwboot_bootmsg() finishes, BootROM is
> able to start receiving xmodem packets without any specific delay or
> setup.
>
> Signed-off-by: Pali Rohár <pali@kernel.org>
> Signed-off-by: Marek Behún <marek.behun@nic.cz>

Reviewed-by: Stefan Roese <sr@denx.de>

Thanks,
Stefan

> ---
> tools/kwboot.c | 36 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/tools/kwboot.c b/tools/kwboot.c
> index c413a8bf51..824ae005b2 100644
> --- a/tools/kwboot.c
> +++ b/tools/kwboot.c
> @@ -717,6 +717,7 @@ out:
> static int
> kwboot_bootmsg(int tty, void *msg)
> {
> + struct kwboot_block block;
> int rc;
> char c;
> int count;
> @@ -747,7 +748,40 @@ kwboot_bootmsg(int tty, void *msg)
>
> kwboot_printv("\n");
>
> - return rc;
> + if (rc)
> + return rc;
> +
> + /*
> + * At this stage we have sent more boot message patterns and BootROM
> + * (at least on Armada XP and 385) started interpreting sent bytes as
> + * part of xmodem packets. If BootROM is expecting SOH byte as start of
> + * a xmodem packet and it receives byte 0xff, then it throws it away and
> + * sends a NAK reply to host. If BootROM does not receive any byte for
> + * 2s when expecting some continuation of the xmodem packet, it throws
> + * away the partially received xmodem data and sends NAK reply to host.
> + *
> + * Therefore for starting xmodem transfer we have two options: Either
> + * wait 2s or send 132 0xff bytes (which is the size of xmodem packet)
> + * to ensure that BootROM throws away any partially received data.
> + */
> +
> + /* flush output queue with remaining boot message patterns */
> + tcflush(tty, TCOFLUSH);
> +
> + /* send one xmodem packet with 0xff bytes to force BootROM to re-sync */
> + memset(&block, 0xff, sizeof(block));
> + kwboot_tty_send(tty, &block, sizeof(block), 0);
> +
> + /*
> + * Sending 132 bytes via 115200B/8-N-1 takes 11.45 ms, reading 132 bytes
> + * takes 11.45 ms, so waiting for 30 ms should be enough.
> + */
> + usleep(30 * 1000);
> +
> + /* flush remaining NAK replies from input queue */
> + tcflush(tty, TCIFLUSH);
> +
> + return 0;
> }
>
> static int

Viele Grüße,
Stefan Roese

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