serial: sirf: fix the issue that HW flow control doesn't work for BT

>From HW spec, when rxfifo's data is less than AFC_RX_THD(RX threshhold), RTS
signal is active. otherwise, RTS signal is inactive.

Crrently the RX threshhold is set as zero, so RTS has no chance to be
active. This patch replaces the default 0 by a positive number.

Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sirfsoc_uart.c b/drivers/tty/serial/sirfsoc_uart.c
index 1d0d47f..48cceaf 100644 (file)
--- a/drivers/tty/serial/sirfsoc_uart.c
+++ b/drivers/tty/serial/sirfsoc_uart.c
@@ -344,7 +344,8 @@ static void sirfsoc_uart_enable_ms(struct uart_port *port)
        if (sirfport->uart_reg->uart_type == SIRF_REAL_UART) {
                wr_regl(port, ureg->sirfsoc_afc_ctrl,
                                rd_regl(port, ureg->sirfsoc_afc_ctrl) |
-                               SIRFUART_AFC_TX_EN | SIRFUART_AFC_RX_EN);
+                               SIRFUART_AFC_TX_EN | SIRFUART_AFC_RX_EN |
+                               SIRFUART_AFC_CTRL_RX_THD);
                if (!sirfport->is_atlas7)
                        wr_regl(port, ureg->sirfsoc_int_en_reg,
                                        rd_regl(port, ureg->sirfsoc_int_en_reg)