Re: [PATCH v5 7/7] riscv: dts: starfive: Add USB dts configuration for JH7110

[Roger Quadros <rogerq@kernel.org>]

Hi Minda,

On 26/04/2023 14:05, Minda Chen wrote:
> 
> 
> On 2023/4/24 22:53, Roger Quadros wrote:
>>
>>
>> On 20/04/2023 14:00, Minda Chen wrote:
>>> Add USB wrapper layer and Cadence USB3 controller dts
>>> configuration for StarFive JH7110 SoC and VisionFive2
>>> Board.
>>> USB controller connect to PHY, The PHY dts configuration
>>> are also added.
>>>
>>> Signed-off-by: Minda Chen <minda.chen@starfivetech.com>
>>> ---
>>>  .../jh7110-starfive-visionfive-2.dtsi         |  7 +++
>>>  arch/riscv/boot/dts/starfive/jh7110.dtsi      | 44 +++++++++++++++++++
>>>  2 files changed, 51 insertions(+)
>>>
>>> diff --git a/arch/riscv/boot/dts/starfive/jh7110-starfive-visionfive-2.dtsi b/arch/riscv/boot/dts/starfive/jh7110-starfive-visionfive-2.dtsi
>>> index 1155b97b593d..fa97ebfd93ad 100644
>>> --- a/arch/riscv/boot/dts/starfive/jh7110-starfive-visionfive-2.dtsi
>>> +++ b/arch/riscv/boot/dts/starfive/jh7110-starfive-visionfive-2.dtsi
>>> @@ -221,3 +221,10 @@
>>>  	pinctrl-0 = <&uart0_pins>;
>>>  	status = "okay";
>>>  };
>>> +
>>> +&usb0 {
>>> +	phys = <&usbphy0>;
>>> +	phy-names = "usb2";
>>> +	dr_mode = "peripheral";
>>> +	status = "okay";
>>> +};
>>> diff --git a/arch/riscv/boot/dts/starfive/jh7110.dtsi b/arch/riscv/boot/dts/starfive/jh7110.dtsi
>>> index 29cd798b6732..eee395e19cdb 100644
>>> --- a/arch/riscv/boot/dts/starfive/jh7110.dtsi
>>> +++ b/arch/riscv/boot/dts/starfive/jh7110.dtsi
>>> @@ -366,6 +366,50 @@
>>>  			status = "disabled";
>>>  		};
>>>  
>>> +		usb0: usb@10100000 {
>>> +			compatible = "starfive,jh7110-usb";
>>> +			reg = <0x0 0x10100000 0x0 0x10000>,
>>> +			      <0x0 0x10110000 0x0 0x10000>,
>>> +			      <0x0 0x10120000 0x0 0x10000>;
>>> +			reg-names = "otg", "xhci", "dev";
>>> +			interrupts = <100>, <108>, <110>;
>>> +			interrupt-names = "host", "peripheral", "otg";
>>> +			clocks = <&stgcrg JH7110_STGCLK_USB0_LPM>,
>>> +				 <&stgcrg JH7110_STGCLK_USB0_STB>,
>>> +				 <&stgcrg JH7110_STGCLK_USB0_APB>,
>>> +				 <&stgcrg JH7110_STGCLK_USB0_AXI>,
>>> +				 <&stgcrg JH7110_STGCLK_USB0_UTMI_APB>;
>>> +			clock-names = "lpm", "stb", "apb", "axi", "utmi_apb";
>>> +			resets = <&stgcrg JH7110_STGRST_USB0_PWRUP>,
>>> +				 <&stgcrg JH7110_STGRST_USB0_APB>,
>>> +				 <&stgcrg JH7110_STGRST_USB0_AXI>,
>>> +				 <&stgcrg JH7110_STGRST_USB0_UTMI_APB>;
>>> +			reset-names = "pwrup", "apb", "axi", "utmi_apb";
>>
>> All this can really be "cdns,usb3" node. The cdns,usb3 driver should
>> do reset and clocks init as it is generic.
>>
> But I can't find clock and reset init in Cadence codes while dwc usb3 can find. 
> It looks only if clocks and reset generic init codes required to be added in  Cadence codes to support generic clock and reset init.
>>> +			starfive,stg-syscon = <&stg_syscon 0x4>;
>>> +			status = "disabled";
>>
>> Only the syscon handling looks starfive specific so only that handling
>> should be done in starfive USB driver.
>>
>> This node should look like this
>>
>>  
>> 	starfive-usb@4 {
>> 		compatible = "starfive,jh7110-usb";
>> 		starfive,stg-syscon = <&stg_syscon 0x4>;
>>
>> 		usb0: usb@10100000 {
>> 			compatible = "cdns,usb3";
>> 			reg = <0x0 0x10100000 0x0 0x10000>,
>> 			      <0x0 0x10110000 0x0 0x10000>,
>> 			      <0x0 0x10120000 0x0 0x10000>;
>> 			reg-names = "otg", "xhci", "dev";
>> 			interrupts = <100>, <108>, <110>;
>> 			interrupt-names = "host", "peripheral", "otg";
>> 			clocks = <&stgcrg JH7110_STGCLK_USB0_LPM>,
>> 				 <&stgcrg JH7110_STGCLK_USB0_STB>,
>> 				 <&stgcrg JH7110_STGCLK_USB0_APB>,
>> 				 <&stgcrg JH7110_STGCLK_USB0_AXI>,
>> 				 <&stgcrg JH7110_STGCLK_USB0_UTMI_APB>;
>> 			clock-names = "lpm", "stb", "apb", "axi", "utmi_apb";
>> 			resets = <&stgcrg JH7110_STGRST_USB0_PWRUP>,
>> 				 <&stgcrg JH7110_STGRST_USB0_APB>,
>> 				 <&stgcrg JH7110_STGRST_USB0_AXI>,
>> 				 <&stgcrg JH7110_STGRST_USB0_UTMI_APB>;
>> 			reset-names = "pwrup", "apb", "axi", "utmi_apb";
>> 			starfive,stg-syscon = <&stg_syscon 0x4>;
>> 			status = "disabled";
>> 		};
>> 	}
>>> In starfife-usb driver you can use of_platform_default_populate()
>> to create the cdns,usb3 child for you.
>>
> But actually the the syscon is not belong to USB. Below is Rob's previous comments. I am follow Rob's comments to change this.

Managing these syscon registers cannot be done in cdns,usb3 driver.
So you definitely need a wrapper driver for that.

>  
>   This pattern of USB wrapper and then a "generic" IP node is discouraged if it is just clocks, resets, power-domains, etc. IOW, unless there's an actual wrapper h/w block with its own registers, then don't do this split. 
>   Merge it all into a single node.
> 
> Rob and Rogers
>   Could you design whether merge the usb nodes？ 
> dt-binding，USB codes are different in two case.
>  

There should ideally be only one USB node and that should use "cdns,usb3" compatible.
Clocks, resets and power-domain handling should be done in cdns,usb3 driver.

But since you also need to manage some syscon registers "cdsn,usb3" driver is not
sufficient for you.

I will leave the DT-binding question for this case to Rob.

cheers,
-roger

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