linux-kernel - Re: [PATCHv4 1/2] usb: USB Type-C connector class

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Date:	Thu, 30 Jun 2016 10:10:25 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	Oliver Neukum <oneukum@...e.com>,
	Felipe Balbi <felipe.balbi@...ux.intel.com>,
	Roger Quadros <rogerq@...com>,
	Rajaram R <rajaram.officemail@...il.com>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCHv4 1/2] usb: USB Type-C connector class

On Wed, Jun 29, 2016 at 04:38:37PM +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.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> ---
[ ... ]

> +
> +What:		/sys/class/typec/<port>-partner/supports_usb_power_delivery
> +Date:		June 2016
> +Contact:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> +Description:
> +		Shows if the partner supports USB Power Delivery.
> +		- 1 if USB Power Delivery is supported
> +		- 0 when it's not
> +
> +
> +What:		/sys/class/typec/<port>-partner/id_header_vdo
> +Date:		June 2016
> +Contact:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> +Description:
> +		If the partner supports USB Power Deliver, shows the VDO
> +		returned from Discover Identity USB Power Delivery command.
> +
> +		If the partner does not support USB Power Delivery, the
> +		attribute is hidden.
> +
On second thought, and after merging the code (and realizing that I don't get
the raw data from the Type-C Port Manager), I am not sure if a raw attribute
is that useful here. It also doesn't provide all information either.

Would it make sense to split it into multiple decoded attributes ?

- vendor-id
  [bit 0..15 of ID header VDO]
- product-type (undefined, hub, peripheral, alternate mode adapter for ufp;
	passive/active for cable plugs)
  Might map into typec_partner_type, but I don't see a 1:1 match.
  [bit 27..29 of ID header VDO]
- alternate-mode-supported
  [bit 26 of ID header VDO]
- capabilities (ufp, dfp, drp, none (?))
  [bit 30/31 of ID header VDO]
- product-id
  [bit 16..31 of Product VDO]

Does this make any sense ?

Thanks,
Guenter