Date:   Fri, 6 Nov 2020 09:03:37 +0100
From:   Amelie DELAUNAY <amelie.delaunay@...com>
To:     Badhri Jagan Sridharan <badhri@...gle.com>,
        Rob Herring <robh@...nel.org>
CC:     Jun Li <lijun.kernel@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Russell King <linux@...linux.org.uk>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        "moderated list:ARM/STM32 ARCHITECTURE" 
        <linux-stm32@...md-mailman.stormreply.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Fabrice Gasnier <fabrice.gasnier@...com>
Subject: Re: [RESEND PATCH v3 1/4] dt-bindings: connector: add power-opmode
 optional property to usb-connector

Hi Badhri,

On 11/6/20 4:10 AM, Badhri Jagan Sridharan wrote:
> Hi Rob and Amelie,
> 
> With regards to discussions in this thread,
> For https://lore.kernel.org/r/20201020093627.256885-2-badhri@google.com,
> I can send in a patch to update the new-source-frs-typec-current property.
> Amelie, If you are already planning to send that I am fine with that as well.
> Let me know !
> 
> To summarize the changes for new-source-frs-typec-current would be,
> 1. Rename to frs-new-source-opmode
> 2. Use string values instead of u32 similar to typec-power-opmode.
> Are these correct ?


You can send patches to rename the new-source-frq-typec-current property 
into frs-new-source-opmode, and update the tcpm as well. You can use the 
typec_find_pwr_opmode(), it will return
enum typec_pwr_opmode {
	TYPEC_PWR_MODE_USB,
	TYPEC_PWR_MODE_1_5A,
	TYPEC_PWR_MODE_3_0A,
	TYPEC_PWR_MODE_PD,
};
Then you have to translate it for FRS.

I'll send a new version of my series to document typec-power-opmode and 
update stusb160x driver and stm32mp15xx-dkx device tree accordingly.

Thanks,
Amelie

> 
> Thanks,
> Badhri
> 
> On Thu, Nov 5, 2020 at 7:55 AM Rob Herring <robh@...nel.org> wrote:
>>
>> On Thu, Nov 5, 2020 at 6:24 AM Jun Li <lijun.kernel@...il.com> wrote:
>>>
>>> Amelie DELAUNAY <amelie.delaunay@...com> 于2020年11月5日周四 下午7:36写道：
>>>>
>>>> On 11/4/20 10:08 PM, Rob Herring wrote:
>>>>> On Fri, Oct 30, 2020 at 04:27:14PM +0100, Amelie DELAUNAY wrote:
>>>>>>
>>>>>>
>>>>>> On 10/30/20 3:29 PM, Rob Herring wrote:
>>>>>>> On Thu, Oct 29, 2020 at 11:49 AM Amelie DELAUNAY <amelie.delaunay@...com> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 10/29/20 4:40 PM, Rob Herring wrote:
>>>>>>>>> On Thu, Oct 29, 2020 at 10:58:03AM +0100, Amelie Delaunay wrote:
>>>>>>>>>> Power operation mode may depends on hardware design, so, add the optional
>>>>>>>>>> property power-opmode for usb-c connector to select the power operation
>>>>>>>>>> mode capability.
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: Amelie Delaunay <amelie.delaunay@...com>
>>>>>>>>>> ---
>>>>>>>>>>      .../bindings/connector/usb-connector.yaml      | 18 ++++++++++++++++++
>>>>>>>>>>      1 file changed, 18 insertions(+)
>>>>>>>>>>
>>>>>>>>>> diff --git a/Documentation/devicetree/bindings/connector/usb-connector.yaml b/Documentation/devicetree/bindings/connector/usb-connector.yaml
>>>>>>>>>> index 728f82db073d..200d19c60fd5 100644
>>>>>>>>>> --- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
>>>>>>>>>> +++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
>>>>>>>>>> @@ -93,6 +93,24 @@ properties:
>>>>>>>>>>            - device
>>>>>>>>>>            - dual
>>>>>>>>>>
>>>>>>>>>> +  power-opmode:
>>>>>>>>>
>>>>>>>>> I've acked this version:
>>>>>>>>>
>>>>>>>>> https://lore.kernel.org/r/20201020093627.256885-2-badhri@google.com
>>>>>>>>>
>>>>>>>>
>>>>>>>> frs is used for Fast Role Swap defined in USB PD spec.
>>>>>>>> I understand it allows to get the same information but I'm wondering why
>>>>>>>> the property name is limited to -frs- in this case. What about a
>>>>>>>> non-power delivery USB-C connector ?
>>>>>>>
>>>>>>> I've got no idea. The folks that know USB-C and PD details need to get
>>>>>>> together and work all this out. To me, it looks like the same thing...
>>>>>>>
>>>>>>
>>>>>> It looks but...
>>>>>>
>>>>>> The purpose of power-opmode property is to configure the USB-C controllers,
>>>>>> especially the non-PD USB-C controllers to determine the power operation
>>>>>> mode that the Type C connector will support and will advertise through CC
>>>>>> pins when it has no power delivery support, whatever the power role: Sink,
>>>>>> Source or Dual
>>>>>> The management of the property is the same that data-role and power-role
>>>>>> properties, and done by USB Type-C Connector Class.
>>>>>>
>>>>>> new-source-frs-typec-current specifies initial current capability of the new
>>>>>> source when vSafe5V is applied during PD3.0 Fast Role Swap. So here, this
>>>>>> property is not applied at usb-c controller configuration level, but during
>>>>>> PD Fast Role Swap, so when the Sink become the Source.
>>>>>> Moreover, the related driver code says FRS can only be supported by DRP
>>>>>> ports. So new-source-frs-typec-current property, in addition to being
>>>>>> specific to PD, is also dedicated to DRP usb-c controller.
>>>>>> The property is managed by Type-C Port Controller Manager for PD.
>>>>>
>>>>> But it's the same set of possible values, right? So we can align the
>>>>> values at least.
>>>>>
>>>>
>>>> USB Power Delivery FRS values are defined in
>>>> include/dt-bindings/usb/pd.h
>>>
>>> I think this can be changed if both can be aligned.
>>>
>>>> to fit with drivers/usb/typec/tcpm/tcpm.c
>>>> frs_typec_current enum.
>>>>
>>>> USB-C power operation mode values are defined in
>>>> include/linux/usb/typec.h with typec_pwr_opmode enum and matching with
>>>> string values of typec_pwr_opmodes tab.
>>>>
>>>> USB PD requires USB-C.
>>>> USB-C doesn't requires USB PD.
>>>>
>>>> drivers/usb/typec/tcpm/tcpm.c already used typec_pwr_opmode values.
>>>>
>>>> USB PD specification Table 6-14 Fixed Supply PDO says:
>>>> Fast Role Swap required USB Type-C Current (see also [USB Type-C 2.0]):
>>>> Value | Description
>>>>    00b  | Fast Swap not supported (default)
>>>>    01b  | Default USB Power
>>>>    10b  | 1.5A @ 5V
>>>>    11b  | 3.0A @ 5V
>>>
>>> This is the value in PDO of sink, the FRS property value(or after translated)
>>> actually is used to compare with above value.
>>>
>>> So I think both properties can share the same "value", maybe string
>>> like below
>>>
>>>    10 static const char * const typec_pwr_opmodes[] = {
>>>    11         [TYPEC_PWR_MODE_USB]    = "default",
>>>    12         [TYPEC_PWR_MODE_1_5A]   = "1.5A",
>>>    13         [TYPEC_PWR_MODE_3_0A]   = "3.0A",
>>>
>>>>
>>>> Note the *see also USB Type-C 2.0*.
>>>>
>>>> USB Type-C specification 4.6.2.1 USB Type-C Current says:
>>>> The USB Type-C connector uses CC pins for configuration including an
>>>> ability for a Source to advertise to its port partner (Sink) the amount
>>>> of current it shall supply:
>>>> • Default is the as-configured for high-power operation current value as
>>>> defined by the USB Specification (500 mA for USB 2.0 ports; 900 mA or
>>>> 1,500 mA for USB 3.2 ports in single-lane or dual-lane operation,
>>>> respectively)
>>>> • 1.5 A
>>>> • 3.0 A
>>>>
>>>>> Can we align the names in some way? power-opmode and frs-source-opmode
>>>>> or ??
>>>
>>> how about typec-power-opmode and frs-new-source-opmode
>>
>> Sure.
>>
>>>
>>>>>
>>>>
>>>> I let USB PD specialists answer.
>>>>
>>>> *frs* property fits with USB PD specification, so with USB PD protocol.
>>>> *power-opmode fits with USB Type-C specification, so with USB-C hardware
>>>> support.
>>>>
>>>>> Are these 2 properties mutually exclusive?
>>>
>>> I think yes.
>>
>> This should work to express that:
>>
>> allOf:
>>    - not:
>>        required:
>>          - typec-power-opmode
>>          - frs-new-source-opmode
>>
>> Rob

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