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tools: kwboot: Force BootROM to flush input queue after boot pattern

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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>
This commit is contained in:
Pali Rohár 2022-01-25 18:13:08 +01:00 committed by Stefan Roese
parent c513fe47dc
commit 2bcd5b1be1
1 changed files with 35 additions and 1 deletions
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36
tools/kwboot.c
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@ -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