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Subject[PATCH AUTOSEL 4.4 01/11] serial: ar933x_uart: set UART_CS_{RX,TX}_READY_ORIDE
Date
From: Daniel Golle <daniel@makrotopia.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@gmail.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Link: https://lore.kernel.org/r/20200207095335.GA179836@makrotopia.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.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 1519d2ca7705f..40194791cde0b 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -294,6 +294,10 @@ 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,
@@ -426,6 +430,10 @@ 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
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