linux-kernel - Re: [PATCHv3 1/2] usb: USB Type-C connector class

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Message-ID: <57712CA2.1020408@roeck-us.net>
Date:	Mon, 27 Jun 2016 06:39:46 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Rajaram R <rajaram.officemail@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	Oliver Neukum <oneukum@...e.com>
Subject: Re: [PATCHv3 1/2] usb: USB Type-C connector class

On 06/27/2016 05:13 AM, Heikki Krogerus wrote:
> Hi,
>
> On Mon, Jun 27, 2016 at 03:51:08PM +0530, Rajaram R wrote:
>> May be I am missing user or usage of the driver.. I see this driver is
>> providing limited information of the Type-C connectors or the port
>> partner
>
> Yes, this interface can't provide directly information received from
> PD commands like Discover Identity. We will have to present the
> partners even when USB PD is not supported and in a consistent
> fashion. Some details will be available in any case indirectly. Like
> if there are modes, there will be devices presenting them, and the
> product type in case of partners will be the partner type.
>
> But there are a couple of attributes I have been thinking about adding
> for the partners:
>
>          supported_data_roles
>          supports_usb_power_delivery
>
> The supported data roles would respond bits 30 and 31 of the ID Header
> VDO. But when the partner does not support USB PD, we will have to
> report "unknown" in it.
>

Or make the attribute invisible in that case.

> Oliver, Guenter! How do you guys feel about those? Is there any use
> for them?
>
Definitely good for debugging and informational. On the top of my head,
I don't immediately see what a user would do with it, though, but then
it would not hurt either to have the information.

I keep wondering if it would make sense to directly expose the ID header
VDO, similar to the alternate mode VDOs, in the partner node.

Guenter

>
>> On Mon, Jun 27, 2016 at 3:21 PM, Heikki Krogerus
>> <heikki.krogerus@...ux.intel.com> wrote:
>>> On Fri, Jun 24, 2016 at 07:54:12PM +0530, Rajaram R wrote:
>>>> On Tue, Jun 21, 2016 at 8:21 PM, Heikki Krogerus
>>>> <heikki.krogerus@...ux.intel.com> 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,
>>>>
>>>> Since we are defining this is as a unified interface for user space,
>>>> will the interface include identity details of local port and peer.
>>>> Or am I over looking something ?
>>>
>>> By peer, do you mean the partners? Sorry but could you elaborate the
>>> question?
>
>
> Thanks,
>