linux-kernel - Re: [PATCH v5 1/6] dt-bindings: add bindings for USB physical connector

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Message-ID: <8434f820-5016-1e5a-c3cb-5d7789dd69c1@samsung.com>
Date:   Mon, 5 Mar 2018 09:18:10 +0100
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        dri-devel@...ts.freedesktop.org, Inki Dae <inki.dae@...sung.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Archit Taneja <architt@...eaurora.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v5 1/6] dt-bindings: add bindings for USB physical
 connector

On 02.03.2018 14:13, Heikki Krogerus wrote:
> Hi,
>
> On Tue, Feb 27, 2018 at 08:11:29AM +0100, Andrzej Hajda wrote:
>> +2. USB-C connector attached to CC controller (s2mm005), HS lines routed
>> +to companion PMIC (max77865), SS lines to USB3 PHY and SBU to DisplayPort.
>> +DisplayPort video lines are routed to the connector via SS mux in USB3 PHY.
>> +
>> +ccic: s2mm005@33 {
>> +	...
>> +	usb_con: connector {
>> +		compatible = "usb-c-connector";
>> +		label = "USB-C";
> Is this child node really necessary? There will never be more then
> one connector per CC line.

But there can be more connectors/cc-lines per IC, for example EZ-PD CCG5[1].

[1]:
http://www.cypress.com/products/ez-pd-ccg5-two-port-usb-type-c-and-power-delivery

>
> We should prefer device_graph* functions over of_graph* and
I guess you mean fwnode_graph* functions.
> acpi_graph* functions in the drivers so we don't have to handle the
> same thing multiple times with separate APIs. Is it still possible if
> there is that connector child node?

Bindings proposed here are OF bindings, I suppose the most important is
to follow OF specification and guidelines and these bindings tries to
follow it.
It looks like it should not be a problem for fwnode framework to handle
such bindings, but it is just my guess. I have not seen any fwnode*
specification I am not sure what is the real purpose of this framework,
but it seems to be just in-kernel abstraction for different firmware
standards (OF, ACPI), so even if it lacks at the moment some
functionality it should not be a barrier for OF bindings.

Regards
Andrzej

>
>> +		ports {
>> +			#address-cells = <1>;
>> +			#size-cells = <0>;
>> +
>> +			port@0 {
>> +				reg = <0>;
>> +				usb_con_hs: endpoint {
>> +					remote-endpoint = <&max77865_usbc_hs>;
>> +				};
>> +			};
>> +			port@1 {
>> +				reg = <1>;
>> +				usb_con_ss: endpoint {
>> +					remote-endpoint = <&usbdrd_phy_ss>;
>> +				};
>> +			};
>> +			port@2 {
>> +				reg = <2>;
>> +				usb_con_sbu: endpoint {
>> +					remote-endpoint = <&dp_aux>;
>> +				};
>> +			};
>> +		};
>> +	};
>> +};
>
> Thanks,
>