On 23/08/2023 18:07, Yu, Richard wrote:
>
> Thank you, Mr. Kozlowski.
>
>>> I am implementing this driver using the Aspeed virtual hub driver as example.
>>>
>>> Just like the Aspeed virtual hub is in the Devicetree:
>>>
>>> vhub: usb-vhub@1e6a0000 {
>>> compatible = "aspeed,ast2600-usb-vhub";
>>> reg = <0x1e6a0000 0x350>;
>>> interrupts = <GIC_SPI 5 IRQ_TYPE_LEVEL_HIGH>;
>>> clocks = <&syscon ASPEED_CLK_GATE_USBPORT1CLK>;
>>> aspeed,vhub-downstream-ports = <7>;
>>> aspeed,vhub-generic-endpoints = <21>;
>>> pinctrl-names = "default";
>>> pinctrl-0 = <&pinctrl_usb2ad_default>;
>>> status = "disabled";
>>> };
>>>
>>> In my case: (I am replacing "udcg" with "vhub" and remove the vehci reference).
>>>
>>> vhub: usb-vhub@80400800 {
>>> compatible = "hpe,gxp-vhub";
>>> reg = <0x80400800 0x0200>, <0x80401000 0x8000>;
>>> reg-names = "vhub", "udc";
>>> interrupts = <13>;
>>> interrupt-parent = <&vic1>;
>>> hpe,vhub-downstream-ports = <4>;
>>> hpe,vhub-generic-endpoints = <16>;
>>> };
>
>
>> The hub is not virtual, it is real. I understand that it is some software block or FPGA, but still I propose to skip any references to virtual.
>
> I will remove any references to "virtual" in comment and documentation.
>
>
>>>>>> + hpe,vehci-downstream-ports:
>>>>>> + description: Number of downstream ports supported by the GXP
>>>>
>>>>
>>>>>> Why do you need this property in DT and what exactly does it represent?
>>>>>> You have one device - EHCI controller - and on some boards it is
>>>>>> further customized? Even though it is the same device?
>>>>>
>>>>> That is correct. We can configure this VHUB Controller to have one
>>>>> to
>>>>> 8 virtual ports. This is similar to the aspeed virtual USB HUB
>>>>> "aspeed,vhub-downstream-ports" moving forward in the next patch we
>>>>> are going to use "hpe,vhub-downstream-ports"
>>>
>>>> Moving forward you need to address this lack of physical presence...
>>>> Aren't these different devices and you just forgot to customize the compatible?
>>>
>>> I don’t fully understand here. Isn't the lack of physical presence
>>> similar to the Aspeed virtual hub driver?
> .
>> I don't know Aspeed virtual hub driver. In any case, driver is irrelevant to the bindings.
>
>> Why setting maximum number of downstream ports or devices would be needed per-board?
>> Do you save some resources that way?
>
> That is correct. Each port/devices will have to allocate resources and create device descriptor entry.
The answer to "why" is not "that is correct".
> Currently, I set the number of downstream ports to be 4. Thus, I will have:
>
> /sys/bus/platform/devices/80400800.vhub/80400800.vhub:p1 <=== for kvm keyboard/mouse
> /sys/bus/platform/devices/80400800.vhub/80400800.vhub:p2 <=== for virtual CD/DVD/ISO image
> /sys/bus/platform/devices/80400800.vhub/80400800.vhub:p3 <=== for virtual USB key
> /sys/bus/platform/devices/80400800.vhub/80400800.vhub:p4 <=== for virtual NIC
So resources in Linux? That's not really relevant and important. I still
do not see the need of this property.
>
> Just like aspeed:
> In g5 (aspeed-g5.dtsi), aspeed,vhub-downstream-ports = <5>;
> In g6 (aspeed-g6.dtsi), aspeed,vhub-downstream-ports = <7>;
I did not review that. Poor or incorrect example is not an argument. If
they introduced obvious bugs or obvious non-DT properties, shall you do
the same?
Best regards,
Krzysztof
