From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH v1 1/1] serial: 8250_dw: Allow hardware flow control to be used Date: Wed, 07 Dec 2016 13:09:49 +0200 Message-ID: <1481108989.17976.9.camel@linux.intel.com> References: <1481063643-11951-1-git-send-email-jason.uy@broadcom.com> <1481063643-11951-2-git-send-email-jason.uy@broadcom.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <1481063643-11951-2-git-send-email-jason.uy@broadcom.com> Sender: linux-kernel-owner@vger.kernel.org To: Jason Uy , Greg Kroah-Hartman , Jiri Slaby Cc: Kefeng Wang , Noam Camus , Heikki Krogerus , Wang Hongcheng , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com List-Id: linux-serial@vger.kernel.org On Tue, 2016-12-06 at 14:34 -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. > It should not affect Intel HW since we are using clock for it (see drivers/mfd/intel-lpss-pci.c, drivers/acpi/acpi_lpss.c). Thus, I'm okay with the change. > Reviewed-by: Scott Branden > Reviewed-by: Ray Jui > Signed-off-by: Jason Uy > --- >  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 459d726..18f1f8b 100644 > --- a/drivers/tty/serial/8250/8250_dw.c > +++ b/drivers/tty/serial/8250/8250_dw.c > @@ -246,11 +246,11 @@ 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); >  } >   > @@ -308,13 +308,11 @@ 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; > @@ -392,6 +390,7 @@ static int dw8250_probe(struct platform_device > *pdev) >   p->iotype = UPIO_MEM; >   p->serial_in = dw8250_serial_in; >   p->serial_out = dw8250_serial_out; > + p->set_termios = dw8250_set_termios; >   >   p->membase = devm_ioremap(dev, regs->start, > resource_size(regs)); >   if (!p->membase) -- Andy Shevchenko Intel Finland Oy