linux-kernel - Re: [PATCH v2] usb: typec: get the vbus source and charge values from the devicetree

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Date:   Mon, 10 Sep 2018 07:11:43 -0600
From:   Angus Ainslie <angus@...ea.ca>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     groeck7@...il.com, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb: typec: get the vbus source and charge values from  the devicetree

Hi Heikki

On 2018-09-10 01:35, Heikki Krogerus wrote:
> On Sun, Sep 09, 2018 at 12:05:31PM -0600, Angus Ainslie (Purism) wrote:
>> If the board is being powered by USB disabling the source and sink
>> can remove power from the board. Allow the source and sink to be
>> initallized based on devicetree values.
>> 
>> Changed since V1:
>> 
>> use devicetree values instead of hardcoded initialization.
>> 
>> Signed-off-by: Angus Ainslie (Purism) <angus@...ea.ca>
>> ---
>>  .../bindings/connector/usb-connector.txt           |  4 ++++
>>  drivers/usb/typec/tcpm.c                           | 14 
>> +++++++++++---
>>  2 files changed, 15 insertions(+), 3 deletions(-)
>> 
>> diff --git 
>> a/Documentation/devicetree/bindings/connector/usb-connector.txt 
>> b/Documentation/devicetree/bindings/connector/usb-connector.txt
>> index 8855bfcfd778..afe851a713c3 100644
>> --- a/Documentation/devicetree/bindings/connector/usb-connector.txt
>> +++ b/Documentation/devicetree/bindings/connector/usb-connector.txt
>> @@ -22,6 +22,10 @@ Optional properties for usb-c-connector:
>>    or Try.SRC, should be "sink" for Try.SNK or "source" for Try.SRC.
>>  - data-role: should be one of "host", "device", "dual"(DRD) if typec
>>    connector supports USB data.
>> +- init-vbus-source: set the initalization value for vbus-source to 
>> true.
>> +  If this property is not present the initial value will be false.
>> +- init-vbus-charge: set the initalization value for vbus-charge to 
>> true.
>> +  If this property is not present the initial value will be false.
> 
> If you put the description of those properties here, you are going to
> need to rename them. Those describe tcpm specific properties, but to
> that file you want to put descriptions of generic properties.
> 

They are tcpm specific but need to go into the connector sub-node to get 
parsed correctly. Would something like below be better ?

diff --git a/Documentation/devicetree/bindings/usb/typec-tcpci.txt 
b/Documentation/devicetree/bindings/usb/typec-tcpci.txt
index 0dd1469e7318..ae0a3e97d9b6 100644
--- a/Documentation/devicetree/bindings/usb/typec-tcpci.txt
+++ b/Documentation/devicetree/bindings/usb/typec-tcpci.txt
@@ -15,6 +15,12 @@ Required sub-node:
    of connector node are specified in
    Documentation/devicetree/bindings/connector/usb-connector.txt

+Optional properties for usb-c-connector sub-node:
+- init-vbus-source: set the initalization value for vbus-source to 
true.
+  If this property is not present the initial value will be false.
+- init-vbus-charge: set the initalization value for vbus-charge to 
true.
+  If this property is not present the initial value will be false.
+
  Example:

  ptn5110@50 {


> Your problem is that you can not cope with a lose of VBUS as a sink,
> right? For that you just need one boolean device property IMO.
> Something like depend-on-vbus.

I thought that it would better to be able to control each independently. 
With my specific hardware I need both defaulted to true but for another 
piece of HW just being able to control one of them might be sufficient.

Thanks
Angus

> 
>>  Required properties for usb-c-connector with power delivery support:
>>  - source-pdos: An array of u32 with each entry providing supported 
>> power
>> diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
>> index ca7bedb46f7f..7f5d4f209e07 100644
>> --- a/drivers/usb/typec/tcpm.c
>> +++ b/drivers/usb/typec/tcpm.c
>> @@ -2462,9 +2462,7 @@ static int tcpm_init_vbus(struct tcpm_port 
>> *port)
>>  {
>>  	int ret;
>> 
>> -	ret = port->tcpc->set_vbus(port->tcpc, false, false);
>> -	port->vbus_source = false;
>> -	port->vbus_charge = false;
>> +	ret = port->tcpc->set_vbus(port->tcpc, port->vbus_source, 
>> port->vbus_charge);
>>  	return ret;
>>  }
>> 
>> @@ -4266,6 +4264,16 @@ static int tcpm_fw_get_caps(struct tcpm_port 
>> *port,
>>  		return -EINVAL;
>>  	port->port_type = port->typec_caps.type;
>> 
>> +	if (fwnode_property_present(fwnode, "init-vbus-source"))
>> +		port->vbus_source = true;
>> +	else
>> +		port->vbus_source = false;
>> +
>> +	if (fwnode_property_present(fwnode, "init-vbus-charge"))
>> +	        port->vbus_charge = true;
>> +	else
>> +	        port->vbus_charge = false;
>> +
>>  	if (port->port_type == TYPEC_PORT_SNK)
>>  		goto sink;
>> 
>> --
>> 2.17.1
> 
> Thanks,