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);