From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roger Quadros Subject: Re: [PATCH v5 1/6] dt-bindings: add bindings for USB physical connector Date: Thu, 15 Mar 2018 19:08:32 +0200 Message-ID: References: <20180227071134.28063-1-a.hajda@samsung.com> <20180227071134.28063-2-a.hajda@samsung.com> <12da0d00-9ab3-3752-793b-e487666f35a3@ti.com> <1c3f8cde-4f9a-306f-b4f9-c0bdc76caf1f@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <1c3f8cde-4f9a-306f-b4f9-c0bdc76caf1f@arm.com> Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org To: Robin Murphy , Andrzej Hajda , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" Cc: Mark Rutland , Felipe Balbi , Archit Taneja , linux-samsung-soc@vger.kernel.org, Laurent Pinchart , Bartlomiej Zolnierkiewicz , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Inki Dae , Chanwoo Choi , Rob Herring , Krzysztof Kozlowski , linux-arm-kernel@lists.infradead.org, Marek Szyprowski List-Id: devicetree@vger.kernel.org On 15/03/18 13:46, Robin Murphy wrote: > On 12/03/18 10:41, Roger Quadros wrote: > [...] >>>>> @@ -0,0 +1,75 @@ >>>>> +USB Connector >>>>> +============= >>>>> + >>>>> +USB connector node represents physical USB connector. It should be >>>>> +a child of USB interface controller. >>>>> + >>>>> +Required properties: >>>>> +- compatible: describes type of the connector, must be one of: >>>>> +    "usb-a-connector", >>>>> +    "usb-b-connector", >>>>> +    "usb-c-connector". >>>> compatible should be just "usb-connector" >>>> >>>> Type should be a property >>>> >>>> type: type of usb connector "A", "B", "AB", "C" >>>> AB is for dual-role connectors. >>> >>> I have proposed such property (and size also) in my first RFC [1]. Rod >>> did not like it :) >>> >>> [1]: https://marc.info/?l=devicetree&m=150660411515233&w=2 >>> >> >> This is what Rob says here https://patchwork.kernel.org/patch/9976043/ >> "We did "type" for hdmi-connector, but I think I'd really prefer >> compatible be used to distinguish as least where it may matter to s/w. >> In the HDMI case, they all are pretty much the same, just different >> physical size." >> >> So the question is. Does it matter to this particular software implementation >> if it is type A,B,C connector? >> If yes, how? >> >> Type A will never have any alternate function. It is always dedicated to USB. > > In USB spec terms, at least. In reality there are things like the cool trick Rockchip SoCs do whereby they can expose the debug UART Rx/Tx through the OTG port's D+/D- pins, and that is on a type A connector in many products. I'm guessing that's probably beyond the scope of this binding, though. > >> Also does the size "full", "micro", "mini" matter to software? > > If it means the user can look in sysfs to easily correlate logical ports with physical connectors that's certainly handy (e.g. on something like Odroid-XU where the two USB3 ports are brought out to an A and a micro-AB connector respectively). But this logic fails if both connectors are the same type/size. This is where the label comes in handy. The labels can be unique and end user can identify the port using that. > > Robin. -- cheers, -roger Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki