linux-kernel - Re: [RESEND PATCH v2 1/6] dt-bindings: connector: add power-opmode optional property to usb-connector

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Message-ID: <31ee8d7c-00b0-0ae1-eea1-e245f215c586@st.com>
Date:   Wed, 23 Sep 2020 11:31:16 +0200
From:   Amelie DELAUNAY <amelie.delaunay@...com>
To:     Jun Li <lijun.kernel@...il.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Russell King <linux@...linux.org.uk>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, lkml <linux-kernel@...r.kernel.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        Fabrice Gasnier <fabrice.gasnier@...com>
Subject: Re: [RESEND PATCH v2 1/6] dt-bindings: connector: add power-opmode
 optional property to usb-connector



On 9/23/20 11:08 AM, Jun Li wrote:
> Amelie Delaunay <amelie.delaunay@...com> 于2020年9月2日周三 下午4:01写道：
>>
>> 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>
>> ---
>> Changes in v2:
>> - Add description for possible operation current values
>> ---
>>   .../bindings/connector/usb-connector.yaml     | 20 +++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/connector/usb-connector.yaml b/Documentation/devicetree/bindings/connector/usb-connector.yaml
>> index 9bd52e63c935..2fd85b9a7e1a 100644
>> --- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
>> +++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
>> @@ -88,6 +88,26 @@ properties:
>>         - device
>>         - dual
>>
>> +  power-opmode:
>> +    description: Determines the power operation mode that the Type C connector
>> +      will support and will advertise through CC pins.
>> +      - "default" corresponds to default USB voltage and current defined by the
>> +        USB 2.0 and USB 3.2 specifications, 5V 500mA for USB 2.0 ports and
>> +        5V 900mA or 1500mA for USB 3.2 ports in single-lane or dual-lane
>> +        operation respectively.
>> +      - "1.5A" and "3.0A", 5V 1.5A and 5V 3.0A respectively, as defined in USB
>> +        Type-C Cable and Connector specification, when Power Delivery is not
>> +        supported.
>> +      - "usb_power_delivery" when Power Delivery is supported, as defined in
>> +        USB Power Delivery specification.
> 
> Why need "usb_power_delivery"? isn't this information can be implied by
> existing properties like if "source-pdos" is present?
> 

power-opmode is an optional property.
usb_power_delivery, as 3.0A, 1.5A or default here, only reflect the 
possible power operation mode you can set and that are understood by 
typec class:
static const char * const typec_pwr_opmodes[] = {
	[TYPEC_PWR_MODE_USB]	= "default",
	[TYPEC_PWR_MODE_1_5A]	= "1.5A",
	[TYPEC_PWR_MODE_3_0A]	= "3.0A",
	[TYPEC_PWR_MODE_PD]	= "usb_power_delivery",
};

But I guess that a Type-C controller with usb power delivery support 
won't use power-opmode property but rather source/sink-pdos.

power-opmode shows what will be advertised through CC pins. I can remove 
usb_power_delivery from the possible values, but what about the user who 
will add power-opmode property to configure his Type-C controller with 
USB power delivery support (sink and/or source by the way) ?
Should I restrict the use of power-opmode to non-USB power delivery 
Type-C controllers ?
Please advise.

Regards,
Amelie


> Li Jun
>> +    allOf:
>> +      - $ref: /schemas/types.yaml#definitions/string
>> +    enum:
>> +      - default
>> +      - 1.5A
>> +      - 3.0A
>> +      - usb_power_delivery
>> +
>>     # The following are optional properties for "usb-c-connector" with power
>>     # delivery support.
>>     source-pdos:
>> --
>> 2.17.1
>>