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* [PATCH] tty: serial: fsl_lpuart: minimum baud rate support
@ 2020-06-25  9:49 Vabhav Sharma
  2020-06-25 10:04 ` Greg KH
  0 siblings, 1 reply; 5+ messages in thread
From: Vabhav Sharma @ 2020-06-25  9:49 UTC (permalink / raw)
  To: gregkh, jslaby, linux-serial, linux-kernel; +Cc: v.sethi, Vabhav Sharma

From: Vabhav Sharma <vabhav.sharma@nxp.com>

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>
---
 drivers/tty/serial/fsl_lpuart.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 90298c4..0fd0fa5f 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1925,6 +1925,10 @@ 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;
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2020-06-26 11:18 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-25  9:49 [PATCH] tty: serial: fsl_lpuart: minimum baud rate support Vabhav Sharma
2020-06-25 10:04 ` Greg KH
2020-06-25 10:12   ` Vabhav Sharma (OSS)
2020-06-25 10:52     ` Greg KH
2020-06-26 11:18       ` Vabhav Sharma (OSS)

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