linux-kernel - Re: [PATCH V2 6/8] arm64: dts: qcom: sc7280: Add EUD dt node and dwc3 connector

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Message-ID: <0e8322f2-0a6b-5b9f-09b1-b1e870cd6dd8@quicinc.com>
Date:   Wed, 15 Dec 2021 18:06:16 +0530
From:   Souradeep Chowdhury <quic_schowdhu@...cinc.com>
To:     Rob Herring <robh@...nel.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <pure.logic@...us-software.ie>,
        <bjorn.andersson@...aro.org>, <greg@...ah.com>,
        <linux-kernel@...r.kernel.org>, <quic_tsoni@...cinc.com>,
        <quic_psodagud@...cinc.com>, <quic_satyap@...cinc.com>,
        <quic_pheragu@...cinc.com>, <quic_rjendra@...cinc.com>,
        <quic_sibis@...cinc.com>, <quic_saipraka@...cinc.com>
Subject: Re: [PATCH V2 6/8] arm64: dts: qcom: sc7280: Add EUD dt node and dwc3
 connector


On 12/14/2021 1:29 AM, Rob Herring wrote:
> On Thu, Dec 02, 2021 at 03:21:25PM +0530, Souradeep Chowdhury wrote:
>> Add the Embedded USB Debugger(EUD) device tree node. The
>> node contains EUD base register region and EUD mode
>> manager register regions along with the interrupt entry.
>> Also add the connector to EUD which is mapped as the child
>> of dwc3. The connector is attached to EUD via port. Also add
>> the role-switch property to dwc3 node.
>>
>> Signed-off-by: Souradeep Chowdhury <quic_schowdhu@...cinc.com>
>> ---
>>   arch/arm64/boot/dts/qcom/sc7280.dtsi | 25 +++++++++++++++++++++++++
>>   1 file changed, 25 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi b/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> index 53a21d0..2d14e5c 100644
>> --- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> @@ -1315,6 +1315,18 @@
>>   				phys = <&usb_2_hsphy>;
>>   				phy-names = "usb2-phy";
>>   				maximum-speed = "high-speed";
>> +				usb-role-switch;
>> +				usb_con: eud_usb_connector {
>> +					compatible = "qcom,usb-connector-eud",
>> +						     "usb-c-connector";
>> +					ports {
>> +						port@0 {
> It is already defined that port@0 of the connector is USB HS data. Is
> that the case here? What about the SS lines?

As per the yaml documentation this is to be used for USB HS lines but in 
this case I am using the port to get the connector fwnode from the eud 
driver and then perform the role switch from the connector parent which 
is the dwc3 controller.  Should I update the yaml file to include this 
description?

>  From the description, it sounds like the data path is DWC3 -> EUD ->
> connector. The DT structure doesn't match that.

EUD is an independent QCOM IP , it is a mini usb hub which can only 
function in device mode. That's why it has been mapped as a separate 
device tree node connected to the type c connector via port endpoint to 
perform a role switch when necessary. I have kept EUD and connector at 
the same level as there is no direct data path from EUD to the connector 
and both are at a level below the controller.

>
>> +							usb2_role_switch: endpoint {
>> +								remote-endpoint = <&eud_ep>;
>> +							};
>> +						};
>> +					};
>> +				};
>>   			};
>>   		};
>>   
>> @@ -1339,6 +1351,19 @@
>>   			interrupts = <GIC_SPI 582 IRQ_TYPE_LEVEL_HIGH>;
>>   		};
>>   
>> +		eud:  eud@...0000 {
>> +			compatible = "qcom,sc7280-eud","qcom,eud";
>> +			reg = <0 0x88e0000 0 0x2000>,
>> +			      <0 0x88e2000 0 0x1000>;
>> +			interrupt-parent = <&pdc>;
>> +			interrupts = <11 IRQ_TYPE_LEVEL_HIGH>;
>> +			port {
>> +				eud_ep: endpoint {
>> +					remote-endpoint = <&usb2_role_switch>;
>> +				};
>> +			};
>> +		};
>> +
>>   		nsp_noc: interconnect@...0000 {
>>   			reg = <0 0x0a0c0000 0 0x10000>;
>>   			compatible = "qcom,sc7280-nsp-noc";
>> -- 
>> 2.7.4
>>
>>