• U
    serial/mxs-auart: increase time to wait for transmitter to become idle · 079a036f
    Uwe Kleine-König 提交于
    Without this patch the driver waits ~1 ms for the UART to become idle. At
    115200n8 this time is (theoretically) enough to transfer 11.5 characters
    (= 115200 bits/s / (10 Bits/char) * 1ms). As the mxs-auart has a fifo size
    of 16 characters the clock is gated too early. The problem is worse for
    lower baud rates.
    
    This only happens to really shut down the transmitter in the middle of a
    transfer if /dev/ttyAPPx isn't opened in userspace (e.g. by a getty) but
    was at least once (because the bootloader doesn't disable the transmitter).
    
    So increase the timeout to 20 ms which should be enough for 9600n8, too.
    Moreover skip gating the clock if the timeout is elapsed.
    
    Cc: stable@vger.kernel.org # v2.6.39+
    Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
    Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    079a036f
mxs-auart.c 27.3 KB