From: Vabhav Sharma <vabhav.sharma@oss.nxp.com>
To: gregkh@linuxfoundation.org, jslaby@suse.com,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: v.sethi@nxp.com, Vabhav Sharma <vabhav.sharma@nxp.com>
Subject: [PATCH] tty: serial: fsl_lpuart: minimum baud rate support
Date: Thu, 25 Jun 2020 15:19:05 +0530 [thread overview]
Message-ID: <1593078545-11272-1-git-send-email-vabhav.sharma@oss.nxp.com> (raw)
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
next reply other threads:[~2020-06-25 9:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 9:49 Vabhav Sharma [this message]
2020-06-25 10:04 ` [PATCH] tty: serial: fsl_lpuart: minimum baud rate support 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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