Re: dwc3: multiple ones and speed?

Re: dwc3: multiple ones and speed?

[Heikki Krogerus]

Hi,

On Thu, Sep 08, 2022 at 10:51:00AM +0200, Daniel Martin wrote:
> Hi Heikki,
> 
> `git blame drivers/usb/dwc3/dwc3-pci.c` said, that you might be the
> right person to ask. ;-)

Felipe is the dwc3 driver and also the USB gadget subsystem
maintainer. I'll add him here, and also the linux-usb ml.

> - Do you know of any device (preferably Intel x86_64) that has more
> than one dwc3 controller?
> - Do you have any speed comparisions for devices with a dwc3 acting in
> device mode (i. e. throughput and latency of a storage gadget)?

I'm sorry I don't. But perhaps Felipe or someone else on the list has?

> I've got a few Rock Pi X at the moment, though its gadget performance
> isn't that satisfying and I don't know if the Cherry Trail Z8350 or
> the included dwc3 is the limiting factor.
> 
> [1] https://wiki.radxa.com/RockpiX

You should explain a bit more about what you are doing, and with which
exact gadget driver?

Br,

-- 
heikki

Re: dwc3: multiple ones and speed?

[Felipe Balbi]

Hi,

Heikki Krogerus <heikki.krogerus@linux.intel.com> writes:
> On Thu, Sep 08, 2022 at 10:51:00AM +0200, Daniel Martin wrote:
>> Hi Heikki,
>> 
>> `git blame drivers/usb/dwc3/dwc3-pci.c` said, that you might be the
>> right person to ask. ;-)
>
> Felipe is the dwc3 driver and also the USB gadget subsystem
> maintainer. I'll add him here, and also the linux-usb ml.
>
>> - Do you know of any device (preferably Intel x86_64) that has more
>> than one dwc3 controller?
>> - Do you have any speed comparisions for devices with a dwc3 acting in
>> device mode (i. e. throughput and latency of a storage gadget)?
>
> I'm sorry I don't. But perhaps Felipe or someone else on the list has?

I've been out of the Intel loop for quite some time, but IIRC some of
the newest cores supporting USB 3.2 on the peripheral side were made so
that SuperSpeed would be handled by one dwc3 instance and SuperSpeed
Plus would be handled by another dwc3 instance altogether.

>> I've got a few Rock Pi X at the moment, though its gadget performance
>> isn't that satisfying and I don't know if the Cherry Trail Z8350 or
>> the included dwc3 is the limiting factor.

why would it be? Can you define "performance"? Which kernel version are
you using? Have you tried latest tag from Linus? What gadget driver are
you using? How have you configured it? Are you running HighSpeed or
SuperSpeed? (IIRC, CherryTrail is superspeed only).

-- 
balbi