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SubjectRe: [PATCH v2 1/1] serial: 8250_dw: Allow hardware flow control to be used
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On Wed, 2017-01-11 at 11:48 -0800, Jason Uy wrote:
> 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>

FWIW:
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Signed-off-by: Jason Uy <jason.uy@broadcom.com>
> ---
>  drivers/tty/serial/8250/8250_dw.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_dw.c
> b/drivers/tty/serial/8250/8250_dw.c
> index c89fafc..c89ae45 100644
> --- 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)

--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

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