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

[Stefan Roese <sr@denx.de>]

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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