linux-kernel - Re: [PATCH 0/3] usb: USB Type-C Class and driver for UCSI

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Date:	Fri, 6 May 2016 07:08:12 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:	Greg KH <gregkh@...uxfoundation.org>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Mathias Nyman <mathias.nyman@...ux.intel.com>,
	Felipe Balbi <balbi@...nel.org>
Subject: Re: [PATCH 0/3] usb: USB Type-C Class and driver for UCSI

On 05/06/2016 01:08 AM, Heikki Krogerus wrote:
> Hi,
>
> On Wed, May 04, 2016 at 08:05:44PM -0700, Guenter Roeck wrote:
>> On Tue, Feb 09, 2016 at 07:01:20PM +0200, Heikki Krogerus wrote:
>>> Hi,
>>>
>>> The OS, or more precisely the user space, needs to be able to control
>>> a few things regarding USB Type-C ports. The first thing that must be
>>> allowed to be controlled is the data role. USB Type-C ports will
>>> select the data role randomly with DRP ports. When USB PD is
>>> supported, also independent (from data role) power role swapping can
>>> be supported together with Alternate Mode control.
>>>
>>> I'm proposing with this set a Class for the Type-C connectors that
>>> gives the user space control over those things on top of getting basic
>>> details about the USB Type-C connectors and also partners. The details
>>> include the capabilities of the port, the supported data and power
>>> roles, supported accessories (audio and debug), supported Alternate
>>> Modes, USB PD support and of course the type of the partner (USB, Alt
>>> Mode, Accessory or Charger), and more or less the same details about
>>> the partner.
>>>
>>> I'm not considering cables with this Class, and I have deliberately
>>> left out some more technical details, like cable orientation, firstly
>>> because I did not see much use for the user space from knowing that
>>> an secondly because that kind of details are not always available for
>>> example with UCSI.
>>>
>>> So the interface to the user space is kept as simple as I dared to
>>> make it.
>>>
>>> NOTE: In case there is somebody wondering, this is not adding USB PD
>>> support to Linux kernel. This is just about USB Type-C.
>>>
>>
>> Hello Heikki,
>>
>> we have implemented a prototype TCPM (USB Type-C Protocol Manager)
>> software on top of your patch set. It will support TCPCI as well
>> as other USB-C controllers such as FUSB302. The plan is to use
>> this software in systems where no separate controller is available.
>
> Interesting. So I'm guessing TCPM is actually an implementation USB PD
> software stack, no? AFAIK FUSB302 has USB PD transceiver, right?
>
Yes, both correct.

>> Is there any chance to advance this patch set ? It would be instrumental
>> to get a unified interface to user space.
>
> I don't have not made any new code for the class driver yet, but I'm
> attempting to prepare v2 next week.
>

Excellent! Please cc me - either this e-mail address or groeck@...omium.org.

Thanks,
Guenter