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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Fugang Duan <fugang.duan@nxp.com>,
        Peng Fan <peng.fan@nxp.com>
Subject: [PATCH 5.4 403/408] tty: serial: fsl_lpuart: fix lpuart32_poll_get_char
Date:   Tue, 27 Oct 2020 14:55:41 +0100
Message-Id: <20201027135513.696350196@linuxfoundation.org>
In-Reply-To: <20201027135455.027547757@linuxfoundation.org>
References: <20201027135455.027547757@linuxfoundation.org>
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From: Peng Fan <peng.fan@nxp.com>

commit 29788ab1d2bf26c130de8f44f9553ee78a27e8d5 upstream.

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@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20200929095509.21680-1-peng.fan@nxp.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/tty/serial/fsl_lpuart.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -666,7 +666,7 @@ static void lpuart32_poll_put_char(struc
 
 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);