linux-kernel - Re: [PATCH v2 08/11] arm64: dts: qcom: sm8350-hdk: add pmic glink node

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Date:   Mon, 13 Feb 2023 13:41:09 +0100
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Bjorn Andersson <andersson@...nel.org>
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 08/11] arm64: dts: qcom: sm8350-hdk: add pmic glink
 node

On 10/02/2023 21:13, Bjorn Andersson wrote:
> On Fri, Feb 10, 2023 at 04:02:11PM +0100, Neil Armstrong wrote:
>> Add the pmic glink node linked with the DWC3 USB controller
>> switched to OTG mode and tagged with usb-role-switch.
>>
>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>> ---
>>   arch/arm64/boot/dts/qcom/sm8350-hdk.dts | 77 ++++++++++++++++++++++++++++-----
>>   1 file changed, 65 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/sm8350-hdk.dts b/arch/arm64/boot/dts/qcom/sm8350-hdk.dts
>> index 54654eb75c28..28fc9a835c5d 100644
>> --- a/arch/arm64/boot/dts/qcom/sm8350-hdk.dts
>> +++ b/arch/arm64/boot/dts/qcom/sm8350-hdk.dts
>> @@ -31,6 +31,40 @@ hdmi_con: endpoint {
>>   		};
>>   	};
>>   
>> +	pmic-glink {
>> +		compatible = "qcom,sm8350-pmic-glink", "qcom,pmic-glink";
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +
>> +		connector@0 {
>> +			compatible = "usb-c-connector";
>> +			reg = <0>;
>> +			power-role = "dual";
>> +			data-role = "dual";
>> +
>> +			ports {
>> +				#address-cells = <1>;
>> +				#size-cells = <0>;
>> +
>> +				port@0 {
>> +					reg = <0>;
>> +
>> +					pmic_glink_hs_in: endpoint {
>> +						remote-endpoint = <&usb_1_dwc3_hs>;
>> +					};
>> +				};
>> +
>> +				port@1 {
>> +					reg = <1>;
>> +
>> +					pmic_glink_ss_in: endpoint {
>> +						remote-endpoint = <&usb_1_dwc3_ss>;
>> +					};
>> +				};
>> +			};
>> +		};
>> +	};
>> +
>>   	vph_pwr: vph-pwr-regulator {
>>   		compatible = "regulator-fixed";
>>   		regulator-name = "vph_pwr";
>> @@ -666,23 +700,42 @@ &usb_1 {
>>   };
>>   
>>   &usb_1_dwc3 {
>> -	/* TODO: Define USB-C connector properly */
>> -	dr_mode = "peripheral";
>> -};
>> +	dr_mode = "otg";
>> +	usb-role-switch;
>>   
>> -&usb_1_hsphy {
>> -	status = "okay";
>> +	ports {
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>>   
>> -	vdda-pll-supply = <&vreg_l5b_0p88>;
>> -	vdda18-supply = <&vreg_l1c_1p8>;
>> -	vdda33-supply = <&vreg_l2b_3p07>;
>> +		port@0 {
>> +			reg = <0>;
>> +
>> +			usb_1_dwc3_hs: endpoint {
>> +				remote-endpoint = <&pmic_glink_hs_in>;
>> +			};
>> +		};
>> +
>> +		port@1 {
>> +			reg = <1>;
>> +
>> +			usb_1_dwc3_ss: endpoint {
>> +				remote-endpoint = <&pmic_glink_ss_in>;
> 
> The connector is indeed the next active component on the SuperSpeed
> lanes for USB. But as you're targeting to introduce QMP on that path,
> connector@...ort@1 would be pointing to QMP/ports/port@N.
> 
> Do you plan to express the datapath between USB and QMP using this port
> at that time? (It's the correct thing to do...)

Yeah we need to figure out, because ultimately the datapath should be:

connector:
   port0 --> usb_1_dwc3_hs
   port1 --> qmpphy --> usb_1_dwc3_ss
   port2 --> fsa4480 --> qmpphy -> dp_controller

And with a retimer, it gets even more complex:

connector:
   port0 --> usb_1_dwc3_hs
   port1 --> retimer --> qmpphy --> usb_1_dwc3_ss
   port2 --> retimer --> qmpphy -> dp_controller

The solution I was using is instead of having chained port/endpoints,
I use multiple endpoints like :

   port0 --> usb_1_dwc3_hs
   port1 --> ep0: usb_1_dwc3_ss
             ep1: qmpphy
   port2 --> ep0: fsa4480
             ep1: dp_controller

But I'm sure this is valid... but it is much simpler.

Neil

> 
> Or will we not describe the SS lanes in this scenario?
> 
> Regards,
> Bjorn
> 
>> +			};
>> +		};
>> +	};
>>   };
>>   
>> -&usb_1_qmpphy {
>> -	status = "okay";
>> +&usb_1_dwc3 {
>> +	dr_mode = "otg";
>> +	usb-role-switch;
>> +};
>>   
>> -	vdda-phy-supply = <&vreg_l6b_1p2>;
>> -	vdda-pll-supply = <&vreg_l1b_0p88>;
>> +&usb_1_dwc3_hs {
>> +	remote-endpoint = <&pmic_glink_hs_in>;
>> +};
>> +
>> +&usb_1_dwc3_ss {
>> +	remote-endpoint = <&pmic_glink_ss_in>;
>>   };
>>   
>>   &usb_2 {
>>
>> -- 
>> 2.34.1
>>