Subject: Re: [PATCH v17 2/3] usb: USB Type-C connector class
To: Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Guenter Roeck <linux@roeck-us.net>
References: <20170221142405.76299-1-heikki.krogerus@linux.intel.com>
 <20170221142405.76299-3-heikki.krogerus@linux.intel.com>
 <ae5d8f3a-859b-c3fa-1427-c25920a82abe@gmail.com>
 <4b4bbffc-db02-3b54-04bc-e7de79b2d9ed@roeck-us.net>
 <07618170-d561-e7fe-08e0-91316c53d832@gmail.com>
 <20170303125940.GA6999@kuha.fi.intel.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
        Felipe Balbi <felipe.balbi@linux.intel.com>,
        Oliver Neukum <oneukum@suse.com>, linux-kernel@vger.kernel.org,
        linux-usb@vger.kernel.org
From: Mats Karrman <mats.dev.list@gmail.com>
Message-ID: <6ddb2eac-03d5-127e-df1e-ad189968e6b2@gmail.com>
Date: Fri, 3 Mar 2017 20:27:08 +0100
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On 2017-03-03 13:59, Heikki Krogerus wrote:

> On Fri, Mar 03, 2017 at 08:29:18AM +0100, Mats Karrman wrote:
> ....

> How would something like that sound to you guys?

Complicated... Need to marinate on that for a while ;)

>> My system is a bit different. It's an i.MX6 SoC with the typec phy and DP controller connected
>> directly to the SoC and it's using DTB/OF.
> Is this "DP controller" a controller that is capable of taking care of
> the USB Power Delivery communication with the partner regarding
> DisplayPort alternate mode?

No, the "DP controller" just talks DP and knows nothing about Type-C or USB PD.
It takes a video stream from the SoC and turns it into a DP link, set up and orchestrated
by the corresponding driver. And all the driver needs from Type-C is the plugged in / interrupt /
plugged out events.

The analog switching between USB / safe / DP signal levels in the Type-C connector is, I think,
best handled by the software doing the USB PD negotiation / Altmode handling (using some GPIOs).

>> Do we need to further standardize attributes under (each) specific alternate mode to
>> include things such as HPD for the DP mode?
> I'm not completely sure what kind of system you have, but I would
> imagine that if we had the bus, your DP controller driver would be the
> port (and partner) alternate mode driver. The bus would bind you to
> the typec phy.

So, both the DP controller and the USB PD phy are I2C devices, and now I have to make them both
attach to the AM bus as well?

BR,
Mats