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

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Message-ID: <CABXOdTesKcwJHFU+VXJJsoY+UHeAFgQ_11+WqoGBE_N2Fr-g-Q@mail.gmail.com>
Date:   Fri, 9 Sep 2016 19:23:20 -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 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 ?

Thanks,
Guenter