linux-kernel - Re: [PATCH 7/8] arm64: dts: qcom: ipq9574: Add USB related nodes

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Message-ID: <365f2609-d3b4-df23-5b6e-7a190815a640@quicinc.com>
Date:   Tue, 7 Mar 2023 12:06:44 +0530
From:   Varadarajan Narayanan <quic_varada@...cinc.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 7/8] arm64: dts: qcom: ipq9574: Add USB related nodes


On 3/6/2023 5:21 PM, Dmitry Baryshkov wrote:
> On 06/03/2023 13:26, Varadarajan Narayanan wrote:
>> Dmitry,
>>
>> On 3/2/2023 9:52 PM, Dmitry Baryshkov wrote:
>>> On Thu, 2 Mar 2023 at 11:57, Varadarajan Narayanan
>>> <quic_varada@...cinc.com> wrote:
>>>> Add USB phy and controller related nodes
>>>>
>>>> Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
>>>> ---
>>>>   arch/arm64/boot/dts/qcom/ipq9574.dtsi | 92 
>>>> +++++++++++++++++++++++++++++++++++
>>>>   1 file changed, 92 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/ipq9574.dtsi 
>>>> b/arch/arm64/boot/dts/qcom/ipq9574.dtsi
>>>> index 2bb4053..319b5bd 100644
>>>> --- a/arch/arm64/boot/dts/qcom/ipq9574.dtsi
>>>> +++ b/arch/arm64/boot/dts/qcom/ipq9574.dtsi
>
> [skipped]
>
>
>>>> +               usb3: usb3@...0000 {
>>> You know the drill. This node is in the wrong place.
>>>
>>>> +                       compatible = "qcom,dwc3";
>>>> +                       reg = <0x8AF8800 0x400>;
>>>> +                       #address-cells = <1>;
>>>> +                       #size-cells = <1>;
>>>> +                       ranges;
>>>> +
>>>> +                       clocks = <&gcc GCC_SNOC_USB_CLK>,
>>>> +                               <&gcc GCC_ANOC_USB_AXI_CLK>,
>>>> +                               <&gcc GCC_USB0_MASTER_CLK>,
>>>> +                               <&gcc GCC_USB0_SLEEP_CLK>,
>>>> +                               <&gcc GCC_USB0_MOCK_UTMI_CLK>;
>>>> +
>>>> +                       clock-names = "sys_noc_axi",
>>>> +                               "anoc_axi",
>>>> +                               "master",
>>>> +                               "sleep",
>>>> +                               "mock_utmi";
>>> Please fix the indentation of the lists.
>>>
>>>> +
>>>> +                       assigned-clocks = <&gcc GCC_SNOC_USB_CLK>,
>>>> +                                         <&gcc GCC_ANOC_USB_AXI_CLK>,
>>> Why do you assign clock rates to the NOC clocks? Should they be set
>>> using the interconnect instead?
>>
>> The SNOC and ANOC run at a fixed speed of 350MHz and 342MHz 
>> respectively and are not scaled. These clocks are for the interface 
>> between the USB block and the SNOC/ANOC. Do we still need to use 
>> interconnect?
>
> Maybe I misunderstand something here. If the snoc and anoc speeds are 
> at 350 MHz and 342 MHz, why do you assign clock-rates of 200 MHz?
>
> Is it enough to call clk_prepare_enable() for these clocks or the rate 
> really needs to be set?

The rate of 200MHz is not being set for the SNOC/ANOC. It is for the
NIU that connects the USB and SNOC/ANOC. The reason for setting the
rate to 200MHz is to configure the RCG parent for these interface
clocks. That said can we configure this RCG standalone in the driver
and enable these clocks?

Thanks
Varada


>
>
>>
>>>> + <&gcc GCC_USB0_MASTER_CLK>,
>>>> +                                         <&gcc 
>>>> GCC_USB0_MOCK_UTMI_CLK>;
>>>> +                       assigned-clock-rates = <200000000>,
>>>> + <200000000>,
>>>> + <200000000>,
>>>> + <24000000>;
>>>> +
>>>> +                       resets = <&gcc GCC_USB_BCR>;
>>>> +                       status = "disabled";
>>>> +
>>>> +                       dwc_0: dwc3@...0000 {
>>>> +                               compatible = "snps,dwc3";
>>>> +                               reg = <0x8A00000 0xcd00>;
>>>> +                               clock-names = "ref";
>>>> +                               clocks = <&gcc 
>>>> GCC_USB0_MOCK_UTMI_CLK>;
>>> clocks before clock-names
>>>
>>>> + interrupts = <GIC_SPI 140 IRQ_TYPE_LEVEL_HIGH>;
>>>> +                               phys = <&qusb_phy_0>, <&usb0_ssphy>;
>>>> +                               phy-names = "usb2-phy", "usb3-phy";
>>>> +                               tx-fifo-resize;
>>>> +                               snps,dis_ep_cache_eviction;
>>>> +                               snps,is-utmi-l1-suspend;
>>>> +                               snps,hird-threshold = /bits/ 8 <0x0>;
>>>> +                               snps,dis_u2_susphy_quirk;
>>>> +                               snps,dis_u3_susphy_quirk;
>>>> + snps,quirk-frame-length-adjustment = <0x0A87F0A0>;
>>>> +                               dr_mode = "host";
>>>> +                       };
>>>> +               };
>>>> +
>>>>                  pcie0_phy: phy@...00 {
>>>>                          compatible = 
>>>> "qcom,ipq9574-qmp-gen3x1-pcie-phy";
>>>>                          reg = <0x00084000 0x1bc>; /* Serdes PLL */
>>>> -- 
>>>> 2.7.4
>>
>> Will address these and post a new revision.
>>
>> Thanks
>>
>> Varada
>>
>