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Date: Fri, 24 Mar 2017 13:31:19 -0500
From: Rob Herring <robh@...nel.org>
To: Andrey Smirnov <andrew.smirnov@...il.com>
Cc: Chris Healy <cphealy@...il.com>,
Guenter Roeck <linux@...ck-us.net>,
Andy Shevchenko <andy.shevchenko@...il.com>,
"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] serdev: Replace serdev_device_write_buf with serdev_device_write
On Mon, Mar 20, 2017 at 11:56 AM, Andrey Smirnov
<andrew.smirnov@...il.com> wrote:
> Convert serdev_device_write_buf's code to be able to transfer amount of
> data potentially exceeding "write room" at the moment of invocation.
>
> To support that, also add serdev_device_write_wakeup.
>
> Drivers wanting to use full extent of serdev_device_write functionality
> asre expected to provide serdev_device_write_wakeup as a sole handler of
> .write_wakeup event or call it as a part of driver's custom
> .write_wakeup code.
>
> Drivers wanting to retain old serdev_device_write_buf behaviour can
> replace those call to calls to serdev_device_write with timeout of
> 0. Providing .write_wakeup handler in such case is optional.
Looks good, just a couple of things.
>
> Cc: cphealy@...il.com
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Andy Shevchenko <andy.shevchenko@...il.com>
> Cc: linux-serial@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
> ---
> drivers/tty/serdev/core.c | 36 +++++++++++++++++++++++++++++++-----
> include/linux/serdev.h | 11 +++++++++--
> 2 files changed, 40 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> index f4c6c90..9962d84 100644
> --- a/drivers/tty/serdev/core.c
> +++ b/drivers/tty/serdev/core.c
> @@ -116,17 +116,41 @@ void serdev_device_close(struct serdev_device *serdev)
> }
> EXPORT_SYMBOL_GPL(serdev_device_close);
>
> -int serdev_device_write_buf(struct serdev_device *serdev,
> - const unsigned char *buf, size_t count)
> +void serdev_device_write_wakeup(struct serdev_device *serdev)
> +{
> + complete(&serdev->write_comp);
> +}
> +EXPORT_SYMBOL_GPL(serdev_device_write_wakeup);
> +
> +int serdev_device_write(struct serdev_device *serdev,
> + const unsigned char *buf, size_t count,
> + unsigned long timeout)
> {
> struct serdev_controller *ctrl = serdev->ctrl;
> + int ret;
>
> - if (!ctrl || !ctrl->ops->write_buf)
> + if (!ctrl || !ctrl->ops->write_buf ||
> + (timeout && !serdev->ops->write_wakeup))
> return -EINVAL;
>
> - return ctrl->ops->write_buf(ctrl, buf, count);
> + mutex_lock(&serdev->write_lock);
> + do {
> + reinit_completion(&serdev->write_comp);
> +
> + ret = ctrl->ops->write_buf(ctrl, buf, count);
> + if (ret < 0)
> + break;
> +
> + buf += ret;
> + count -= ret;
> +
> + } while (count &&
> + wait_for_completion_timeout(&serdev->write_comp,
> + timeout));
This is going to wait for timeout time on each loop. We want the
timeout passed in to be the total time.
> + mutex_unlock(&serdev->write_lock);
> + return ret < 0 ? ret : (count ? -ETIMEDOUT : 0);
> }
> -EXPORT_SYMBOL_GPL(serdev_device_write_buf);
> +EXPORT_SYMBOL_GPL(serdev_device_write);
>
> void serdev_device_write_flush(struct serdev_device *serdev)
> {
> @@ -232,6 +256,8 @@ struct serdev_device *serdev_device_alloc(struct serdev_controller *ctrl)
> serdev->dev.parent = &ctrl->dev;
> serdev->dev.bus = &serdev_bus_type;
> serdev->dev.type = &serdev_device_type;
> + init_completion(&serdev->write_comp);
> + mutex_init(&serdev->write_lock);
> return serdev;
> }
> EXPORT_SYMBOL_GPL(serdev_device_alloc);
> diff --git a/include/linux/serdev.h b/include/linux/serdev.h
> index 5176cdc..18cbbed 100644
> --- a/include/linux/serdev.h
> +++ b/include/linux/serdev.h
> @@ -39,12 +39,17 @@ struct serdev_device_ops {
> * @nr: Device number on serdev bus.
> * @ctrl: serdev controller managing this device.
> * @ops: Device operations.
> + * @write_comp Completion used by serdev_device_write internally
> + * @write_lock Mutext used to esure exclusive access to the bus when
> + * writing data with serdev_device_write()
> */
> struct serdev_device {
> struct device dev;
> int nr;
> struct serdev_controller *ctrl;
> const struct serdev_device_ops *ops;
> + struct completion write_comp;
> + struct mutex write_lock;
> };
>
> static inline struct serdev_device *to_serdev_device(struct device *d)
> @@ -186,10 +191,12 @@ 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);
> -int serdev_device_write_buf(struct serdev_device *, const unsigned char *, size_t);
> +void serdev_device_write_wakeup(struct serdev_device *);
> +int serdev_device_write(struct serdev_device *, const unsigned char *, size_t, unsigned long);
> void serdev_device_write_flush(struct serdev_device *);
> int serdev_device_write_room(struct serdev_device *);
>
> +
> /*
> * serdev device driver functions
> */
> @@ -223,7 +230,7 @@ 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 int serdev_device_write_buf(struct serdev_device *sdev, const unsigned char *buf, size_t count)
We probably should keep a wrapper for serdev_device_write_buf to avoid
cross tree dependencies. However, the Nokia BT support is going to
have them anyway.
> +static inline int serdev_device_write(struct serdev_device *sdev, const unsigned char *buf, size_t count)
> {
> return -ENODEV;
> }
> --
> 2.9.3
>
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