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[PATCHv3 02/10] serdev: add serdev_device_wait_until_sent

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  [PATCHv3 02/10] serdev: add serdev_device_wait_until_sent Sebastian Reichel <sre@kernel.org> - 2017-03-28 18:10 +0200
    Re: [PATCHv3 02/10] serdev: add serdev_device_wait_until_sent Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-08 19:00 +0200
      Re: [PATCHv3 02/10] serdev: add serdev_device_wait_until_sent Rob Herring <robh+dt@kernel.org> - 2017-04-10 15:50 +0200
        Re: [PATCHv3 02/10] serdev: add serdev_device_wait_until_sent Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-10 16:10 +0200

#1611142 — [PATCHv3 02/10] serdev: add serdev_device_wait_until_sent

Add method, which waits until the transmission buffer has been sent.
Note, that the change in ttyport_write_wakeup is related, since
tty_wait_until_sent will hang without that change.

Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
---
Changes since PATCHv2:
 * Avoid goto in ttyport_write_wakeup
---
 drivers/tty/serdev/core.c           | 11 +++++++++++
 drivers/tty/serdev/serdev-ttyport.c | 18 ++++++++++++++----
 include/linux/serdev.h              |  3 +++
 3 files changed, 28 insertions(+), 4 deletions(-)

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..50dc75c4d204 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
 
@@ -46,11 +47,11 @@ static void ttyport_write_wakeup(struct tty_port *port)
 	struct serdev_controller *ctrl = port->client_data;
 	struct serport *serport = serdev_controller_get_drvdata(ctrl);
 
-	if (!test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags))
-		return;
-
-	if (test_bit(SERPORT_ACTIVE, &serport->flags))
+	if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags) &&
+	    test_bit(SERPORT_ACTIVE, &serport->flags))
 		serdev_controller_write_wakeup(ctrl);
+
+	wake_up_interruptible_poll(&port->tty->write_wait, POLLOUT);
 }
 
 static const struct tty_port_client_operations client_ops = {
@@ -167,6 +168,14 @@ static void ttyport_set_flow_control(struct serdev_controller *ctrl, bool enable
 	tty_set_termios(tty, &ktermios);
 }
 
+static void ttyport_wait_until_sent(struct serdev_controller *ctrl, long timeout)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+
+	tty_wait_until_sent(tty, timeout);
+}
+
 static const struct serdev_controller_ops ctrl_ops = {
 	.write_buf = ttyport_write_buf,
 	.write_flush = ttyport_write_flush,
@@ -175,6 +184,7 @@ static const struct serdev_controller_ops ctrl_ops = {
 	.close = ttyport_close,
 	.set_flow_control = ttyport_set_flow_control,
 	.set_baudrate = ttyport_set_baudrate,
+	.wait_until_sent = ttyport_wait_until_sent,
 };
 
 struct device *serdev_tty_port_register(struct tty_port *port,
diff --git a/include/linux/serdev.h b/include/linux/serdev.h
index 9519da6253a8..a308b206d204 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -81,6 +81,7 @@ struct serdev_controller_ops {
 	void (*close)(struct serdev_controller *);
 	void (*set_flow_control)(struct serdev_controller *, bool);
 	unsigned int (*set_baudrate)(struct serdev_controller *, unsigned int);
+	void (*wait_until_sent)(struct serdev_controller *, long);
 };
 
 /**
@@ -186,6 +187,7 @@ int serdev_device_open(struct serdev_device *);
 void serdev_device_close(struct serdev_device *);
 unsigned int serdev_device_set_baudrate(struct serdev_device *, unsigned int);
 void serdev_device_set_flow_control(struct serdev_device *, bool);
+void serdev_device_wait_until_sent(struct serdev_device *, long);
 int serdev_device_write_buf(struct serdev_device *, const unsigned char *, size_t);
 void serdev_device_write_flush(struct serdev_device *);
 int serdev_device_write_room(struct serdev_device *);
@@ -223,6 +225,7 @@ static inline unsigned int serdev_device_set_baudrate(struct serdev_device *sdev
 	return 0;
 }
 static inline void serdev_device_set_flow_control(struct serdev_device *sdev, bool enable) {}
+static inline void serdev_device_wait_until_sent(struct serdev_device *sdev, long timeout) {}
 static inline int serdev_device_write_buf(struct serdev_device *sdev, const unsigned char *buf, size_t count)
 {
 	return -ENODEV;
-- 
2.11.0

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#1619331

On Tue, Mar 28, 2017 at 05:59:31PM +0200, Sebastian Reichel wrote:
> Add method, which waits until the transmission buffer has been sent.
> Note, that the change in ttyport_write_wakeup is related, since
> tty_wait_until_sent will hang without that change.
> 
> Acked-by: Rob Herring <robh@kernel.org>
> Acked-by: Pavel Machek <pavel@ucw.cz>
> Signed-off-by: Sebastian Reichel <sre@kernel.org>
> ---
> Changes since PATCHv2:
>  * Avoid goto in ttyport_write_wakeup
> ---
>  drivers/tty/serdev/core.c           | 11 +++++++++++
>  drivers/tty/serdev/serdev-ttyport.c | 18 ++++++++++++++----
>  include/linux/serdev.h              |  3 +++
>  3 files changed, 28 insertions(+), 4 deletions(-)
> 
> 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);

Is this still needed now that we have serdev_device_write() with an
unlimited timeout available?

thanks,

greg k-h

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#1619950

On Sat, Apr 8, 2017 at 11:57 AM, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> On Tue, Mar 28, 2017 at 05:59:31PM +0200, Sebastian Reichel wrote:
>> Add method, which waits until the transmission buffer has been sent.
>> Note, that the change in ttyport_write_wakeup is related, since
>> tty_wait_until_sent will hang without that change.
>>
>> Acked-by: Rob Herring <robh@kernel.org>
>> Acked-by: Pavel Machek <pavel@ucw.cz>
>> Signed-off-by: Sebastian Reichel <sre@kernel.org>
>> ---
>> Changes since PATCHv2:
>>  * Avoid goto in ttyport_write_wakeup
>> ---
>>  drivers/tty/serdev/core.c           | 11 +++++++++++
>>  drivers/tty/serdev/serdev-ttyport.c | 18 ++++++++++++++----
>>  include/linux/serdev.h              |  3 +++
>>  3 files changed, 28 insertions(+), 4 deletions(-)
>>
>> 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);
>
> Is this still needed now that we have serdev_device_write() with an
> unlimited timeout available?

Yes, because only this waits until the data is on the wire.

Rob

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#1619959

On Mon, Apr 10, 2017 at 08:46:57AM -0500, Rob Herring wrote:
> On Sat, Apr 8, 2017 at 11:57 AM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> > On Tue, Mar 28, 2017 at 05:59:31PM +0200, Sebastian Reichel wrote:
> >> Add method, which waits until the transmission buffer has been sent.
> >> Note, that the change in ttyport_write_wakeup is related, since
> >> tty_wait_until_sent will hang without that change.
> >>
> >> Acked-by: Rob Herring <robh@kernel.org>
> >> Acked-by: Pavel Machek <pavel@ucw.cz>
> >> Signed-off-by: Sebastian Reichel <sre@kernel.org>
> >> ---
> >> Changes since PATCHv2:
> >>  * Avoid goto in ttyport_write_wakeup
> >> ---
> >>  drivers/tty/serdev/core.c           | 11 +++++++++++
> >>  drivers/tty/serdev/serdev-ttyport.c | 18 ++++++++++++++----
> >>  include/linux/serdev.h              |  3 +++
> >>  3 files changed, 28 insertions(+), 4 deletions(-)
> >>
> >> 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);
> >
> > Is this still needed now that we have serdev_device_write() with an
> > unlimited timeout available?
> 
> Yes, because only this waits until the data is on the wire.

What "wire" is that?  The serial wire?  How do you know this?  Many usb
to serial devices have no way to determine this, given that there is
another uart hanging off of the end of a USB connection.

Doesn't serdev_device_write() return when the write is finished?  I
think we need some good documentation here for all of the different
variants of how to send data, as I'm sure confused...

thanks,

greg k-h

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