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tools: kwboot: Check whether baudrate was set to requested value

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The tcsetattr() function can return 0 even if baudrate was not changed.
Check whether baudrate was changed to requested value, and in case of
arbitrary baudrate, check whether the set value is within 3% tolerance.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
This commit is contained in:
Marek Behún
2021-09-24 23:07:07 +02:00
committed by Stefan Roese
parent 93b55636b0
commit 99a3d02370
1 changed files with 32 additions and 0 deletions
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32
tools/kwboot.c
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@@ -567,6 +567,13 @@ kwboot_tty_baudrate_to_speed(int baudrate)
} }
} }
static int
_is_within_tolerance(int value, int reference, int tolerance)
{
return 100 * value >= reference * (100 - tolerance) &&
100 * value <= reference * (100 + tolerance);
}
static int static int
kwboot_tty_change_baudrate(int fd, int baudrate) kwboot_tty_change_baudrate(int fd, int baudrate)
{ {
@@ -601,7 +608,32 @@ kwboot_tty_change_baudrate(int fd, int baudrate)
if (rc) if (rc)
return rc; return rc;
rc = tcgetattr(fd, &tio);
if (rc)
return rc;
if (cfgetospeed(&tio) != speed || cfgetispeed(&tio) != speed)
goto baud_fail;
#ifdef BOTHER
/*
* Check whether set baudrate is within 3% tolerance.
* If BOTHER is defined, Linux always fills out c_ospeed / c_ispeed
* with real values.
*/
if (!_is_within_tolerance(tio.c_ospeed, baudrate, 3))
goto baud_fail;
if (!_is_within_tolerance(tio.c_ispeed, baudrate, 3))
goto baud_fail;
#endif
return 0; return 0;
baud_fail:
fprintf(stderr, "Could not set baudrate to requested value\n");
errno = EINVAL;
return -1;
} }
static int static int