linux-kernel - [PATCH 4.14 074/126] serial: ar933x_uart: set UART_CS_{RX,TX}_READY

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Date:   Tue, 10 Mar 2020 13:41:35 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chuanhong Guo <gch981213@...il.com>,
        Daniel Golle <daniel@...rotopia.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 074/126] serial: ar933x_uart: set UART_CS_{RX,TX}_READY_ORIDE

From: Daniel Golle <daniel@...rotopia.org>

[ Upstream commit 87c5cbf71ecbb9e289d60a2df22eb686c70bf196 ]

On AR934x this UART is usually not initialized by the bootloader
as it is only used as a secondary serial port while the primary
UART is a newly introduced NS16550-compatible.
In order to make use of the ar933x-uart on AR934x without RTS/CTS
hardware flow control, one needs to set the
UART_CS_{RX,TX}_READY_ORIDE bits as other than on AR933x where this
UART is used as primary/console, the bootloader on AR934x typically
doesn't set those bits.
Setting them explicitely on AR933x should not do any harm, so just
set them unconditionally.

Tested-by: Chuanhong Guo <gch981213@...il.com>
Signed-off-by: Daniel Golle <daniel@...rotopia.org>
Link: https://lore.kernel.org/r/20200207095335.GA179836@makrotopia.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/tty/serial/ar933x_uart.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/tty/serial/ar933x_uart.c b/drivers/tty/serial/ar933x_uart.c
index ed545a61413c0..ac56a5131a9cc 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -289,6 +289,10 @@ static void ar933x_uart_set_termios(struct uart_port *port,
 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
 			    AR933X_UART_CS_HOST_INT_EN);
 
+	/* enable RX and TX ready overide */
+	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
+		AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);
+
 	/* reenable the UART */
 	ar933x_uart_rmw(up, AR933X_UART_CS_REG,
 			AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
@@ -421,6 +425,10 @@ static int ar933x_uart_startup(struct uart_port *port)
 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
 			    AR933X_UART_CS_HOST_INT_EN);
 
+	/* enable RX and TX ready overide */
+	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
+		AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);
+
 	/* Enable RX interrupts */
 	up->ier = AR933X_UART_INT_RX_VALID;
 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
-- 
2.20.1