serial: ar933x_uart: set UART_CS_{RX,TX}_READY_ORIDE

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.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/ar933x_uart.c

@@ -286,6 +286,10 @@ 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,
@@ -418,6 +422,10 @@ 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);