linux-kernel - Re: [PATCH 07/10] serdev: add serdev_device_wait_until

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Date:   Tue, 7 Mar 2017 16:55:08 +0100
From:   Sebastian Reichel <sre@...nel.org>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Mark Rutland <mark.rutland@....com>,
        "open list:BLUETOOTH DRIVERS" <linux-bluetooth@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 07/10] serdev: add serdev_device_wait_until_sent

Hi,

On Tue, Mar 07, 2017 at 09:34:49AM -0600, Rob Herring wrote:
> On Sat, Mar 4, 2017 at 5:58 AM, Sebastian Reichel <sre@...nel.org> wrote:
> > Add method, which waits until the transmission buffer has been sent.
> >
> > Signed-off-by: Sebastian Reichel <sre@...nel.org>
> > ---
> >  drivers/tty/serdev/core.c           | 11 +++++++++++
> >  drivers/tty/serdev/serdev-ttyport.c | 15 ++++++++++++++-
> >  include/linux/serdev.h              |  3 +++
> >  3 files changed, 28 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> > index f4c6c90add78..a63b74031e22 100644
> > --- a/drivers/tty/serdev/core.c
> > +++ b/drivers/tty/serdev/core.c
> > @@ -173,6 +173,17 @@ void serdev_device_set_flow_control(struct serdev_device *serdev, bool enable)
> >  }
> >  EXPORT_SYMBOL_GPL(serdev_device_set_flow_control);
> >
> > +void serdev_device_wait_until_sent(struct serdev_device *serdev, long timeout)
> > +{
> > +       struct serdev_controller *ctrl = serdev->ctrl;
> > +
> > +       if (!ctrl || !ctrl->ops->wait_until_sent)
> > +               return;
> > +
> > +       ctrl->ops->wait_until_sent(ctrl, timeout);
> > +}
> > +EXPORT_SYMBOL_GPL(serdev_device_wait_until_sent);
> > +
> >  static int serdev_drv_probe(struct device *dev)
> >  {
> >         const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
> > diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
> > index d05393594f15..db2bc601e554 100644
> > --- a/drivers/tty/serdev/serdev-ttyport.c
> > +++ b/drivers/tty/serdev/serdev-ttyport.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/serdev.h>
> >  #include <linux/tty.h>
> >  #include <linux/tty_driver.h>
> > +#include <linux/poll.h>
> >
> >  #define SERPORT_ACTIVE         1
> >
> > @@ -47,10 +48,13 @@ static void ttyport_write_wakeup(struct tty_port *port)
> >         struct serport *serport = serdev_controller_get_drvdata(ctrl);
> >
> >         if (!test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags))
> > -               return;
> > +               goto out;
> >
> >         if (test_bit(SERPORT_ACTIVE, &serport->flags))
> >                 serdev_controller_write_wakeup(ctrl);
> > +
> > +out:
> > +       wake_up_interruptible_poll(&port->tty->write_wait, POLLOUT);
> 
> Shouldn't this be separate patch?

That change is needed for tty_wait_until_sent to work correctly, which
starts with a wait_event_interruptible_timeout() on write_wait.

-- Sebastian

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