linux-kernel - Re: [RFC PATCH v3 1/2] usb: typec: USB Type-C Port Manager (tcpm)

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Date:   Sun, 11 Sep 2016 19:23:47 -0700
From:   Guenter Roeck <groeck@...gle.com>
To:     Jun Li <jun.li@....com>
Cc:     Guenter Roeck <groeck@...omium.org>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Chandra Sekhar Anagani <chandra.sekhar.anagani@...el.com>,
        Bruce Ashfield <bruce.ashfield@...driver.com>,
        Bin Gao <bin.gao@...el.com>,
        Pranav Tipnis <pranav.tipnis@...el.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [RFC PATCH v3 1/2] usb: typec: USB Type-C Port Manager (tcpm)

On Sun, Sep 11, 2016 at 7:16 PM, Jun Li <jun.li@....com> wrote:
> Hi Guenter
>
>> -----Original Message-----
>> From: Guenter Roeck [mailto:groeck@...gle.com]
>> Sent: Saturday, September 10, 2016 10:23 AM
>> To: Jun Li <jun.li@....com>
>> Cc: Guenter Roeck <groeck@...omium.org>; Felipe Balbi
>> <felipe.balbi@...ux.intel.com>; Chandra Sekhar Anagani
>> <chandra.sekhar.anagani@...el.com>; Bruce Ashfield
>> <bruce.ashfield@...driver.com>; Bin Gao <bin.gao@...el.com>; Pranav Tipnis
>> <pranav.tipnis@...el.com>; Heikki Krogerus
>> <heikki.krogerus@...ux.intel.com>; linux-kernel@...r.kernel.org; linux-
>> usb@...r.kernel.org
>> Subject: Re: [RFC PATCH v3 1/2] usb: typec: USB Type-C Port Manager (tcpm)
>>
>> On Fri, Sep 9, 2016 at 5:26 PM, Jun Li <jun.li@....com> wrote:
>> > Hi Guenter,
>> >
>> >> -----Original Message-----
>> >> From: linux-usb-owner@...r.kernel.org [mailto:linux-usb-
>> >> owner@...r.kernel.org] On Behalf Of Guenter Roeck
>> >> Sent: Wednesday, August 24, 2016 5:11 AM
>> >> To: Felipe Balbi <felipe.balbi@...ux.intel.com>
>> >> Cc: Chandra Sekhar Anagani <chandra.sekhar.anagani@...el.com>; Bruce
>> >> Ashfield <bruce.ashfield@...driver.com>; Bin Gao <bin.gao@...el.com>;
>> >> Pranav Tipnis <pranav.tipnis@...el.com>; Heikki Krogerus
>> >> <heikki.krogerus@...ux.intel.com>; linux-kernel@...r.kernel.org;
>> >> linux- usb@...r.kernel.org; Guenter Roeck <groeck@...omium.org>
>> >> Subject: [RFC PATCH v3 1/2] usb: typec: USB Type-C Port Manager
>> >> (tcpm)
>> >>
>> >> This driver implements the USB Type-C Power Delivery state machine
>> >> for both source and sink ports. Alternate mode support is not fully
>> >> implemented.
>> >>
>> >> The driver attaches to the USB Type-C class code implemented in the
>> >> following patches.
>> >>
>> >>       usb: typec: add driver for Intel Whiskey Cove PMIC USB Type-C PHY
>> >>       usb: USB Type-C connector class
>> >>
>> >> This driver only implements the state machine. Lower level drivers
>> >> are responsible for
>> >> - Reporting VBUS status and activating VBUS
>> >> - Setting CC lines and providing CC line status
>> >> - Setting line polarity
>> >> - Activating and deactivating VCONN
>> >> - Setting the current limit
>> >> - Activating and deactivating PD message transfers
>> >> - Sending and receiving PD messages
>> >>
>> >> The driver provides both a functional API as well as callbacks for
>> >> lower level drivers.
>> >>
>> >> Signed-off-by: Guenter Roeck <groeck@...omium.org>
>> >> ---
>> >
>> > A specific question, if power sink wants to request a new power level
>> > after SNK_READY, how to handle it with this tcpm?
>> >
>>
>> So far I have considered the required power level to be static, based on
>> our curent implementations. That should be easy to change, though, with an
>> additional API function, to be called from a low level driver.
>> Do you have that requirement, and would such a function meet your needs ?
>>
>
> So you are going to make port->tcpc->config to be dynamic to meet my need?
>
What would that help ? How would tcpm get informed that the power
requirements changed without an API function telling it that power
requirements changed ?

Guenter