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tty: serial: fsl_lpuart: minimum baud rate support

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The formula for the baud rate is
baud rate = "baud clock / ((OSR+1) × SBR)

Algorithm used in function lpuart32_serial_setbrg() only changes
the SBR. Even with maxmum value put in, OSR stays at 0x7 and the
lowest baud rate would be ~ 2600 bps

Update the algorithm to allow driver operation at 1200,2400 or 600 bps

Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
Link: https://lore.kernel.org/r/1593170434-13524-1-git-send-email-vabhav.sharma@oss.nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vabhav Sharma 2020-06-26 16:50:34 +05:30 committed by Greg Kroah-Hartman
parent 3550f8979a
commit d10ee1d191
1 changed files with 3 additions and 0 deletions
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3
drivers/tty/serial/fsl_lpuart.c
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@ -1925,6 +1925,9 @@ static void __lpuart32_serial_setbrg(struct uart_port *port,
tmp_sbr++;
}
if (tmp_sbr > UARTBAUD_SBR_MASK)
continue;
if (tmp_diff <= baud_diff) {
baud_diff = tmp_diff;
osr = tmp_osr;