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Groups > linux.kernel > #1522073

Re: [PATHCv10 1/2] usb: USB Type-C connector class

From Guenter Roeck <linux@roeck-us.net>
Newsgroups linux.kernel
Subject Re: [PATHCv10 1/2] usb: USB Type-C connector class
Date 2016-11-14 21:50 +0100
Message-ID <sDwmt-3t4-1@gated-at.bofh.it> (permalink)
References <sj4M9-4KI-11@gated-at.bofh.it> <sj4M9-4KI-13@gated-at.bofh.it> <sDmds-5fH-23@gated-at.bofh.it> <sDoIi-709-7@gated-at.bofh.it>
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On Mon, Nov 14, 2016 at 02:32:35PM +0200, Heikki Krogerus wrote:
> Hi Greg,
> 
> On Mon, Nov 14, 2016 at 10:51:48AM +0100, Greg KH wrote:
> > On Mon, Sep 19, 2016 at 02:16:56PM +0300, Heikki Krogerus wrote:
> > > The purpose of USB Type-C connector class is to provide
> > > unified interface for the user space to get the status and
> > > basic information about USB Type-C connectors on a system,
> > > control over data role swapping, and when the port supports
> > > USB Power Delivery, also control over power role swapping
> > > and Alternate Modes.
> > > 
> > > Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> > > Tested-by: Guenter Roeck <linux@roeck-us.net>
> > > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > > ---
> > >  Documentation/ABI/testing/sysfs-class-typec |  218 ++++++
> > >  Documentation/usb/typec.txt                 |  103 +++
> > >  MAINTAINERS                                 |    9 +
> > >  drivers/usb/Kconfig                         |    2 +
> > >  drivers/usb/Makefile                        |    2 +
> > >  drivers/usb/typec/Kconfig                   |    7 +
> > >  drivers/usb/typec/Makefile                  |    1 +
> > >  drivers/usb/typec/typec.c                   | 1075 +++++++++++++++++++++++++++
> > >  include/linux/usb/typec.h                   |  252 +++++++
> > >  9 files changed, 1669 insertions(+)
> > >  create mode 100644 Documentation/ABI/testing/sysfs-class-typec
> > >  create mode 100644 Documentation/usb/typec.txt
> > >  create mode 100644 drivers/usb/typec/Kconfig
> > >  create mode 100644 drivers/usb/typec/Makefile
> > >  create mode 100644 drivers/usb/typec/typec.c
> > >  create mode 100644 include/linux/usb/typec.h
> > 
[ ... ]

> > > +
> > > +int typec_connect(struct typec_port *port, struct typec_connection *con)
> > > +{
> > > +	int ret;
> > > +
> > > +	if (!con->partner && !con->cable)
> > > +		return -EINVAL;
> > > +
> > > +	port->connected = 1;
> > > +	port->data_role = con->data_role;
> > > +	port->pwr_role = con->pwr_role;
> > > +	port->vconn_role = con->vconn_role;
> > > +	port->pwr_opmode = con->pwr_opmode;
> > > +
> > > +	kobject_uevent(&port->dev.kobj, KOBJ_CHANGE);
> > 
> > This worries me.  Who is listening for it?  What will you do with it?
> > Shouldn't you just poll on an attribute file instead?
> 
> Oliver! Did you need this or can we remove it?
> 
> I remember I removed the "connected" attribute because you did not see
> any use for it at one point. I don't remember the reason exactly why?
> 

The Android team tells me that they are currently using the udev events
to track port role changes, and to detect presence of port partner.

Also, there are plans to track changes on usbc*cable to differentiate
between cable attach vs. device being attached on the remote end. 

What is the problem with using kobject_uevent() and thus presumably
udev events ?

Thanks,
Guenter

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Thread

Re: [PATHCv10 1/2] usb: USB Type-C connector class Greg KH <gregkh@linuxfoundation.org> - 2016-11-14 11:00 +0100
  Re: [PATHCv10 1/2] usb: USB Type-C connector class Heikki Krogerus <heikki.krogerus@linux.intel.com> - 2016-11-14 13:40 +0100
    Re: [PATHCv10 1/2] usb: USB Type-C connector class Greg KH <gregkh@linuxfoundation.org> - 2016-11-14 15:20 +0100
      Re: [PATHCv10 1/2] usb: USB Type-C connector class Heikki Krogerus <heikki.krogerus@linux.intel.com> - 2016-11-14 15:40 +0100
        Re: [PATHCv10 1/2] usb: USB Type-C connector class Greg KH <gregkh@linuxfoundation.org> - 2016-11-14 16:10 +0100
    Re: [PATHCv10 1/2] usb: USB Type-C connector class Guenter Roeck <linux@roeck-us.net> - 2016-11-14 15:40 +0100
      Re: [PATHCv10 1/2] usb: USB Type-C connector class Oliver Neukum <oneukum@suse.com> - 2016-11-16 10:00 +0100
    Re: [PATHCv10 1/2] usb: USB Type-C connector class Guenter Roeck <linux@roeck-us.net> - 2016-11-14 21:50 +0100
      Re: [PATHCv10 1/2] usb: USB Type-C connector class Greg KH <gregkh@linuxfoundation.org> - 2016-11-15 08:10 +0100
        Re: [PATHCv10 1/2] usb: USB Type-C connector class Guenter Roeck <linux@roeck-us.net> - 2016-11-15 10:30 +0100
          Re: [PATHCv10 1/2] usb: USB Type-C connector class Badhri Jagan Sridharan <badhri@google.com> - 2016-11-16 01:20 +0100
            Re: [PATHCv10 1/2] usb: USB Type-C connector class Heikki Krogerus <heikki.krogerus@linux.intel.com> - 2016-11-16 10:40 +0100
              Re: [PATHCv10 1/2] usb: USB Type-C connector class Greg KH <gregkh@linuxfoundation.org> - 2016-11-16 10:50 +0100
                Re: [PATHCv10 1/2] usb: USB Type-C connector class Heikki Krogerus <heikki.krogerus@linux.intel.com> - 2016-11-16 12:20 +0100
                Re: [PATHCv10 1/2] usb: USB Type-C connector class Oliver Neukum <oneukum@suse.com> - 2016-11-16 12:40 +0100
                Re: [PATHCv10 1/2] usb: USB Type-C connector class Badhri Jagan Sridharan <badhri@google.com> - 2016-11-16 15:40 +0100
                Re: [PATHCv10 1/2] usb: USB Type-C connector class Heikki Krogerus <heikki.krogerus@linux.intel.com> - 2016-11-16 15:50 +0100
              Re: [PATHCv10 1/2] usb: USB Type-C connector class Oliver Neukum <oneukum@suse.com> - 2016-11-16 10:50 +0100
  Re: [PATHCv10 1/2] usb: USB Type-C connector class Badhri Jagan Sridharan <badhri@google.com> - 2016-11-16 16:30 +0100
  Re: [PATHCv10 1/2] usb: USB Type-C connector class Heikki Krogerus <heikki.krogerus@linux.intel.com> - 2016-11-16 16:30 +0100
    Re: [PATHCv10 1/2] usb: USB Type-C connector class Greg KH <gregkh@linuxfoundation.org> - 2016-11-16 16:40 +0100
      Re: [PATHCv10 1/2] usb: USB Type-C connector class Heikki Krogerus <heikki.krogerus@linux.intel.com> - 2016-11-17 09:30 +0100

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