linux-kernel - Re: [PATCH V3 5/7] arm64: dts: qcom: sc7280: Add EUD dt node and dwc3 connector

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Message-ID: <43850d22-0e50-76c4-2f05-b768401ff49c@quicinc.com>
Date:   Mon, 17 Jan 2022 10:37:19 +0530
From:   Souradeep Chowdhury <quic_schowdhu@...cinc.com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <pure.logic@...us-software.ie>,
        <greg@...ah.com>, <linux-kernel@...r.kernel.org>,
        <tsoni@...eaurora.org>, <psodagud@...eaurora.org>,
        <satyap@...eaurora.org>, <pheragu@...eaurora.org>,
        <rnayak@...eaurora.org>, <sibis@...eaurora.org>,
        <saiprakash.ranjan@...eaurora.org>
Subject: Re: [PATCH V3 5/7] arm64: dts: qcom: sc7280: Add EUD dt node and dwc3
 connector


On 1/7/2022 6:23 AM, Bjorn Andersson wrote:
> On Tue 04 Jan 03:58 PST 2022, 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 {
> I think this is backwards.
>
> Iiuc you have dwc3 <-> EUD <-> connector, where the connector typically
> would be represented in relation to a Type-C controller.
>
> So I think this graph should be looking something like:
>
>
> dwc3 {
>      ports {
>          port {
>              dwc3_eud: endpoint {
>                  remote-endpoint = <&eud_ep>;
>              };
>          };
>      };
> };
>
> eud {
>      ports {
>          port {
>              eud_dwc3: endpoint {
>                  remote-endpoint = <&dwc3_eud>;
>              };
>          };
>
>          port {
>              eud_con: endpoint {
>                  remote-endpoint = <&con_eud>;
>              };
>          };
>      };
> };
>
> connector {
>      compatible = "usb-c-connector";
>
>      ports {
>          port {
>              con_eud: endpoint {
>                  remote-endpoint = <&eud_con>;
>              };
>          };
>      };
> };
>
> With EUD "forwarding" the role switching requests from the connector, or
> overriding them if the EUD is enabled.
>
> Alternatively the dwc3 would be in a graph with both the eud and the
> connector, but I don't know how to ensure that the EUD decision takes
> precedence over the type-c controllers role request...
>
>
> In the case of us having a type-c controller, such as the pmic_glink,
> the connector node would then be a child of the controller.
Ack. Will align the device tree with this structure.
>
> Regards,
> Bjorn
>
>> +					compatible = "qcom,usb-connector-eud",
>> +						     "usb-c-connector";
>> +					ports {
>> +						port@0 {
>> +							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
>>