serial: 8250_dw: Allow hardware flow control to be used

In the most common use case, the Synopsys DW UART driver does not
set the set_termios callback function.  This prevents UPSTAT_AUTOCTS
from being set when the UART flag CRTSCTS is set.  As a result, the
driver will use software flow control as opposed to hardware flow
control.

To fix the problem, the set_termios callback function is set to the
DW specific function.  The logic to set UPSTAT_AUTOCTS is moved so
that any clock error will not affect setting the hardware flow
control.

Reviewed-by: Scott Branden <scott.branden@broadcom.com>
Reviewed-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Jason Uy <jason.uy@broadcom.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index c89fafc..c89ae45 100644 (file)
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -248,11 +248,11 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
        if (!ret)
                p->uartclk = rate;
 
+out:
        p->status &= ~UPSTAT_AUTOCTS;
        if (termios->c_cflag & CRTSCTS)
                p->status |= UPSTAT_AUTOCTS;
 
-out:
        serial8250_do_set_termios(p, termios, old);
 }
 
@@ -326,13 +326,11 @@ static void dw8250_quirks(struct uart_port *p, struct dw8250_data *data)
                        p->serial_in = dw8250_serial_in32;
                        data->uart_16550_compatible = true;
                }
-               p->set_termios = dw8250_set_termios;
        }
 
        /* Platforms with iDMA */
        if (platform_get_resource_byname(to_platform_device(p->dev),
                                         IORESOURCE_MEM, "lpss_priv")) {
-               p->set_termios = dw8250_set_termios;
                data->dma.rx_param = p->dev->parent;
                data->dma.tx_param = p->dev->parent;
                data->dma.fn = dw8250_idma_filter;
@@ -414,6 +412,7 @@ static int dw8250_probe(struct platform_device *pdev)
        p->serial_in    = dw8250_serial_in;
        p->serial_out   = dw8250_serial_out;
        p->set_ldisc    = dw8250_set_ldisc;
+       p->set_termios  = dw8250_set_termios;
 
        p->membase = devm_ioremap(dev, regs->start, resource_size(regs));
        if (!p->membase)