Because this currently requires a driver "hack" which is not considered to be a valid approach for a commercial product.
The reason why 8 kHz polling is not used is simple: the USB 2.0 FS standard does not support it by default. You would need HS for that - and that's where things get tricky. The frequency the bus is working at is much higher and thus the design of the PCB needs to be really exact - in fact it's quite a hard task with 2-layer PCBs. The tolerances are just generally much lower and you would most likely see units that would either kick back to FS or not even authenticate at all with Windows. Generally 4-layer+ PCBs are used for USB 2.0 HS products which then again costs more. In addition, you would require a beefier MCU (as if 72 MHz STM32s weren't already an overkill for peripherals) and in many cases an additional external PHY making the PCB design for an already constrained space a harder task.
Conclusion: too much stuff to worry about with a negligible gain.
It's too soon to say "negligible" before you try a real 8khz mouse. And, high speed USB on 2-layer pcb is possible, in fact , following the layout guideline , it's quite easy.
Really? Look at / Post screenshot of your via usb 3.0 controller and it's device subtree expanded when mouse not attached.
If "generic usb hub" disappear - than you simply have not right hardware.
And what about my first question?
yes, sorry, the mouse in question is an intellimouse explorer 3.0 legends edition with a default polling rate of 125 hz. the 1000 hz works fine but in 2.0 usbs the polling rate switches to the listed numbers of 62 hz and 32 hz and because the usb 3.0 cant go that low it breaks, I think.
here is the screenshot as requested:
I assure you there is no usb hub.
>I assure you there is no usb hub.
My friend, there IS usb hub. No matter it is not separate device - it is present in hardware path to mouse.
>mouse in question is an intellimouse explorer 3.0 legends edition with a default polling rate of 125 hz
Nice, now we can be sure that problem lay inside PC.
>the usb 3.1a socket and the other usb 3.0's are the front panel
as i can understand you have some second xHCI controller. what is the picture of device manager if you attach mouse to this controller (port of this controller)?
p.s. at second screenshot i can see some errors of using setup if you have composite devices - install filter with "Process Parent" checkbox set. It's very easy now - look at green lines only