lkml.org 
[lkml]   [2017]   [Mar]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v17 2/3] usb: USB Type-C connector class
    From
    Date
    On 03/02/2017 07:22 AM, Mats Karrman wrote:
    > Hi Heikki,
    >
    > Good to see things are happening with Type-C!
    >
    > On 2017-02-21 15:24, Heikki Krogerus wrote:
    >
    >> ...
    >> +When connected, the partner will be presented also as its own device under
    >> +/sys/class/typec/. The parent of the partner device will always be the port it
    >> +is attached to. The partner attached to port "port0" will be named
    >> +"port0-partner". Full path to the device would be
    >> +/sys/class/typec/port0/port0-partner/.
    >
    > A "/port0" too much?
    >
    >> +
    >> +The cable and the two plugs on it may also be optionally presented as their own
    >> +devices under /sys/class/typec/. The cable attached to the port "port0" port
    >> +will be named port0-cable and the plug on the SOP Prime end (see USB Power
    >> +Delivery Specification ch. 2.4) will be named "port0-plug0" and on the SOP
    >> +Double Prime end "port0-plug1". The parent of a cable will always be the port,
    >> +and the parent of the cable plugs will always be the cable.
    >> +
    >> +If the port, partner or cable plug support Alternate Modes, every supported
    >> +Alternate Mode SVID will have their own device describing them. The Alternate
    >> +Modes will not be attached to the typec class. The parent of an alternate mode
    >> +will be the device that supports it, so for example an alternate mode of
    >> +port0-partner will bees presented under /sys/class/typec/port0-partner/. Every
    >
    > bees?
    >
    >> +mode that is supported will have its own group under the Alternate Mode device
    >> +named "mode<index>", for example /sys/class/typec/port0/<alternate mode>/mode1/.
    >> +The requests for entering/exiting a mode can be done with "active" attribute
    >> +file in that group.
    >> +
    >> ...
    >
    > I'm hoping to find time to upgrade the kernel and try these patches in my system.
    >
    > Looking forward, one thing I have run into is how to connect the typec driver with a
    > driver for an alternate mode. E.g. the DisplayPort Alternate Mode specification
    > includes the HPD (hot plug) and HPD-INT (hot plug interrupt) signals as bits in the
    > Attention message. These signals are needed by the DisplayPort driver to know when to
    > start negotiation etc.
    > Have you got any thoughts on how to standardize such interfaces?
    >

    That really depends on the lower level driver. For Chromebooks, where the Type-C
    Protocol Manager runs on the EC, we have an extcon driver which reports the pin states
    to the graphics drivers and connects to the Type-C class code using the Type-C class
    API. I still need to update, re-test, and publish that code. The published code in
    https://chromium.googlesource.com/chromiumos/third_party/kernel/, branch chromeos-4.4,
    shows how it can be done, though that code currently still uses the Android Type-C
    infrastructure.

    Guenter

    \
     
     \ /
      Last update: 2017-03-03 04:13    [W:6.405 / U:0.976 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site