On Thu, Aug 07, 2014 at 12:16:59PM -0400, Murali Karicheri wrote:
> On 08/07/2014 11:29 AM, Peter Hurley wrote:
> >On 05/01/2014 03:04 PM, Murali Karicheri wrote:
> >>8250 uart driver currently supports only software assisted hw flow
> >>control. The software assisted hw flow control maintains a hw_stopped
> >>flag in the tty structure to stop and start transmission and use modem
> >>status interrupt for the event to drive the handshake signals. This is
> >>not needed if hw has flow control capabilities. This patch adds a
> >>DT attribute for enabling hw flow control for a uart port. Also skip
> >>stop and start if this flag is present in flag field of the port
> >>structure.
> >>
> >>Signed-off-by: Murali Karicheri<m-karicheri2@xxxxxx>
> >>
> >>CC: Rob Herring<robh+dt@xxxxxxxxxx>
> >>CC: Pawel Moll<pawel.moll@xxxxxxx>
> >>CC: Mark Rutland<mark.rutland@xxxxxxx>
> >>CC: Ian Campbell<ijc+devicetree@xxxxxxxxxxxxxx>
> >>CC: Kumar Gala<galak@xxxxxxxxxxxxxx>
> >>CC: Randy Dunlap<rdunlap@xxxxxxxxxxxxx>
> >>CC: Greg Kroah-Hartman<gregkh@xxxxxxxxxxxxxxxxxxx>
> >>CC: Jiri Slaby<jslaby@xxxxxxx>
> >>CC: Santosh Shilimkar<santosh.shilimkar@xxxxxx>
> >>---
> >> .../devicetree/bindings/serial/of-serial.txt | 1 +
> >> drivers/tty/serial/8250/8250_core.c | 6 ++++--
> >> drivers/tty/serial/of_serial.c | 4 ++++
> >> drivers/tty/serial/serial_core.c | 12 +++++++++---
> >> 4 files changed, 18 insertions(+), 5 deletions(-)
> >>
> >[...]
> >
> >>diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> >>index b68550d..851707a 100644
> >>--- a/drivers/tty/serial/serial_core.c
> >>+++ b/drivers/tty/serial/serial_core.c
> >>@@ -174,8 +174,12 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
> >> if (tty->termios.c_cflag& CBAUD)
> >> uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
> >> }
> >>-
> >>- if (tty_port_cts_enabled(port)) {
> >>+ /*
> >>+ * if hw support flow control without software intervention,
> >>+ * then skip the below check
> >>+ */
> >>+ if (tty_port_cts_enabled(port)&&
> >>+ !(uport->flags& UPF_HARD_FLOW)) {
> >> spin_lock_irq(&uport->lock);
> >> if (!(uport->ops->get_mctrl(uport)& TIOCM_CTS))
> >> tty->hw_stopped = 1;
> >>@@ -2772,7 +2776,9 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
> >>
> >> uport->icount.cts++;
> >>
> >>- if (tty_port_cts_enabled(port)) {
> >>+ /* skip below code if the hw flow control is supported */
> >>+ if (tty_port_cts_enabled(port)&&
> >>+ !(uport->flags& UPF_HARD_FLOW)) {
> >Why is a modem status interrupt being generated for DCTS
> >if autoflow control is enabled?
> >
> >This should be:
> >
> > WARN_ON_ONCE(uport->flags& UPF_HARD_FLOW);
> >
> >to indicate a mis-configured driver/device.
> This patch is already merged to the upstream branch and if you see any
> issue, please
> post a patch for review.
If someone points out a problem in a patch of yours that is accepted
upstream, it is nice to provide a fix, otherwise I will just revert it
upstream, as it looks to be incorrect.
So, should I just revert it?
greg k-h
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