linux-kernel - [PATCH] tty: serial: fsl_lpuart: fix lpuart32_poll_get

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Message-Id: <20200929095509.21680-1-peng.fan@nxp.com>
Date:   Tue, 29 Sep 2020 17:55:09 +0800
From:   Peng Fan <peng.fan@....com>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org,
        andrew.smirnov@...il.com
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-imx@....com, Peng Fan <peng.fan@....com>,
        Fugang Duan <fugang.duan@....com>
Subject: [PATCH] tty: serial: fsl_lpuart: fix lpuart32_poll_get_char

The watermark is set to 1, so we need to input two chars to trigger RDRF
using the original logic. With the new logic, we could always get the
char when there is data in FIFO.

Suggested-by: Fugang Duan <fugang.duan@....com>
Signed-off-by: Peng Fan <peng.fan@....com>
---
 drivers/tty/serial/fsl_lpuart.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 645bbb24b433..1c37280b6c0c 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -680,7 +680,7 @@ static void lpuart32_poll_put_char(struct uart_port *port, unsigned char c)
 
 static int lpuart32_poll_get_char(struct uart_port *port)
 {
-	if (!(lpuart32_read(port, UARTSTAT) & UARTSTAT_RDRF))
+	if (!(lpuart32_read(port, UARTWATER) >>  UARTWATER_RXCNT_OFF))
 		return NO_POLL_CHAR;
 
 	return lpuart32_read(port, UARTDATA);
-- 
2.28.0