qemu emulation for USB ports of Allwinner H3

qemu emulation for USB ports of Allwinner H3

[Guenter Roeck]

Hi,

the Allwinner H3 USB port qemu emulation creates separate USB ports
for its EHCI and OHCI controllers, resulting in a total of 8 USB ports.
From the orangepi-pc emulation:

# lsusb
Bus 005 Device 001: ID 1d6b:0002
Bus 003 Device 001: ID 1d6b:0002
Bus 001 Device 001: ID 1d6b:0002
Bus 008 Device 001: ID 1d6b:0002
Bus 006 Device 001: ID 1d6b:0001
Bus 004 Device 001: ID 1d6b:0001
Bus 002 Device 001: ID 1d6b:0002
Bus 009 Device 001: ID 1d6b:0001
Bus 007 Device 001: ID 1d6b:0001

The SoC supports EHCI companion interfaces, and my understanding is that
it only has four physical USB ports. Does the real hardware instantiate
separate EHCI and OHCI interfaces (for a total of 8 USB ports), or does it
use the companion functionality ?

If the real hardware only instantiates four USB ports (or, in other words,
if it utilizes EHCI companion functionality), would it make sense to
reflect that in qemu ?

Thanks,
Guenter

Re: qemu emulation for USB ports of Allwinner H3

[Gerd Hoffmann]

On Sun, Sep 08, 2024 at 11:36:18AM GMT, Guenter Roeck wrote:
> Hi,
> 
> the Allwinner H3 USB port qemu emulation creates separate USB ports
> for its EHCI and OHCI controllers, resulting in a total of 8 USB ports.
> From the orangepi-pc emulation:
> 
> # lsusb
> Bus 005 Device 001: ID 1d6b:0002
> Bus 003 Device 001: ID 1d6b:0002
> Bus 001 Device 001: ID 1d6b:0002
> Bus 008 Device 001: ID 1d6b:0002
> Bus 006 Device 001: ID 1d6b:0001
> Bus 004 Device 001: ID 1d6b:0001
> Bus 002 Device 001: ID 1d6b:0002
> Bus 009 Device 001: ID 1d6b:0001
> Bus 007 Device 001: ID 1d6b:0001
> 
> The SoC supports EHCI companion interfaces, and my understanding is that
> it only has four physical USB ports. Does the real hardware instantiate
> separate EHCI and OHCI interfaces (for a total of 8 USB ports), or does it
> use the companion functionality ?

Well, on the guest side you'll see 8 ports even when using the companion
functionality.  Each physical usb port has one ehci port (used when you
plug in usb 2.0+ devices) and one ohci port (used when you plug in usb
1.1 devices).

The main difference is on the qemu backend side.  When using the
companion functionality you have a single qemu usb bus accepting both
1.1 and 2.0+ devices.  When not using the companion functionality you
have one usb bus accepting 2.0+ devices and another usb bus accepting
usb 1.1 devices ...

The guest-visible difference is an per-port bit in ehci registers which
controls whenever ehci or the companion manages the device plugged in.
This bit exists for backward compatibility (guests without ehci driver
can manage all devices via ohci, with usb 2.0+ devices being downgraded
to 1.1 compatibility mode then).

> If the real hardware only instantiates four USB ports (or, in other words,
> if it utilizes EHCI companion functionality), would it make sense to
> reflect that in qemu ?

Yes.

take care,
  Gerd

Re: qemu emulation for USB ports of Allwinner H3

[Niek Linnenbank]

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Hello Guenter, Gerd,

Thanks for bringing up the question. To be honest I do not know a lot about
USB internals.
When adding the orangepi-pc board emulation, it seemed fairly easy to add
it, but apart from a few basic tests, I did not use the USB functionality
extensively.

I do own the actual Orange Pi PC board hardware, so I downloaded the
'Orangepipc_2.0.8_ubuntu_bionic_server_linux5.4.65.7z' image from the
official page to test:
http://www.orangepi.org/html/hardWare/computerAndMicrocontrollers/service-and-support/Orange-Pi-PC.html

After booting that image from an SD card with a serial console, this is the
output from the same 'lsusb' command:

root@orangepipc:~# lsusb
Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 009 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
root@orangepipc:~# uname -a
Linux orangepipc 5.4.65-sunxi #2.0.8 SMP Mon Oct 26 10:20:38 CST 2020
armv7l armv7l armv7l GNU/Linux
root@orangepipc:~# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.5 LTS"

It does look like the same output compared to what we see under Qemu. But
I'm not very sure if this confirms we are emulating correctly or not.

Regards,
Niek

On Mon, Sep 9, 2024 at 11:33 AM Gerd Hoffmann <kraxel@redhat.com> wrote:

> On Sun, Sep 08, 2024 at 11:36:18AM GMT, Guenter Roeck wrote:
> > Hi,
> >
> > the Allwinner H3 USB port qemu emulation creates separate USB ports
> > for its EHCI and OHCI controllers, resulting in a total of 8 USB ports.
> > From the orangepi-pc emulation:
> >
> > # lsusb
> > Bus 005 Device 001: ID 1d6b:0002
> > Bus 003 Device 001: ID 1d6b:0002
> > Bus 001 Device 001: ID 1d6b:0002
> > Bus 008 Device 001: ID 1d6b:0002
> > Bus 006 Device 001: ID 1d6b:0001
> > Bus 004 Device 001: ID 1d6b:0001
> > Bus 002 Device 001: ID 1d6b:0002
> > Bus 009 Device 001: ID 1d6b:0001
> > Bus 007 Device 001: ID 1d6b:0001
> >
> > The SoC supports EHCI companion interfaces, and my understanding is that
> > it only has four physical USB ports. Does the real hardware instantiate
> > separate EHCI and OHCI interfaces (for a total of 8 USB ports), or does
> it
> > use the companion functionality ?
>
> Well, on the guest side you'll see 8 ports even when using the companion
> functionality.  Each physical usb port has one ehci port (used when you
> plug in usb 2.0+ devices) and one ohci port (used when you plug in usb
> 1.1 devices).
>
> The main difference is on the qemu backend side.  When using the
> companion functionality you have a single qemu usb bus accepting both
> 1.1 and 2.0+ devices.  When not using the companion functionality you
> have one usb bus accepting 2.0+ devices and another usb bus accepting
> usb 1.1 devices ...
>
> The guest-visible difference is an per-port bit in ehci registers which
> controls whenever ehci or the companion manages the device plugged in.
> This bit exists for backward compatibility (guests without ehci driver
> can manage all devices via ohci, with usb 2.0+ devices being downgraded
> to 1.1 compatibility mode then).
>
> > If the real hardware only instantiates four USB ports (or, in other
> words,
> > if it utilizes EHCI companion functionality), would it make sense to
> > reflect that in qemu ?
>
> Yes.
>
> take care,
>   Gerd
>
>

-- 
Niek Linnenbank

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Re: qemu emulation for USB ports of Allwinner H3

[Guenter Roeck]

On 9/13/24 15:20, Niek Linnenbank wrote:
> Hello Guenter, Gerd,
> 
> Thanks for bringing up the question. To be honest I do not know a lot about USB internals.
> When adding the orangepi-pc board emulation, it seemed fairly easy to add it, but apart from a few basic tests, I did not use the USB functionality extensively.
> 
> I do own the actual Orange Pi PC board hardware, so I downloaded the 'Orangepipc_2.0.8_ubuntu_bionic_server_linux5.4.65.7z' image from the official page to test:
> http://www.orangepi.org/html/hardWare/computerAndMicrocontrollers/service-and-support/Orange-Pi-PC.html <http://www.orangepi.org/html/hardWare/computerAndMicrocontrollers/service-and-support/Orange-Pi-PC.html>
> 
> After booting that image from an SD card with a serial console, this is the output from the same 'lsusb' command:
> 
> root@orangepipc:~# lsusb
> Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 009 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> root@orangepipc:~# uname -a
> Linux orangepipc 5.4.65-sunxi #2.0.8 SMP Mon Oct 26 10:20:38 CST 2020 armv7l armv7l armv7l GNU/Linux
> root@orangepipc:~# cat /etc/lsb-release
> DISTRIB_ID=Ubuntu
> DISTRIB_RELEASE=18.04
> DISTRIB_CODENAME=bionic
> DISTRIB_DESCRIPTION="Ubuntu 18.04.5 LTS"
> 
> It does look like the same output compared to what we see under Qemu. But I'm not very sure if this confirms we are emulating correctly or not.
> 

Yes, I found that as well, and Gerd has reported the same. The main difference,
as far as I can see, is that the host sees different register contents.
I am not sure if that is worth fixing. Either case it is not my highest priority.

Thanks,
Guenter

> Regards,
> Niek
> 
> On Mon, Sep 9, 2024 at 11:33 AM Gerd Hoffmann <kraxel@redhat.com <mailto:kraxel@redhat.com>> wrote:
> 
>     On Sun, Sep 08, 2024 at 11:36:18AM GMT, Guenter Roeck wrote:
>      > Hi,
>      >
>      > the Allwinner H3 USB port qemu emulation creates separate USB ports
>      > for its EHCI and OHCI controllers, resulting in a total of 8 USB ports.
>      > From the orangepi-pc emulation:
>      >
>      > # lsusb
>      > Bus 005 Device 001: ID 1d6b:0002
>      > Bus 003 Device 001: ID 1d6b:0002
>      > Bus 001 Device 001: ID 1d6b:0002
>      > Bus 008 Device 001: ID 1d6b:0002
>      > Bus 006 Device 001: ID 1d6b:0001
>      > Bus 004 Device 001: ID 1d6b:0001
>      > Bus 002 Device 001: ID 1d6b:0002
>      > Bus 009 Device 001: ID 1d6b:0001
>      > Bus 007 Device 001: ID 1d6b:0001
>      >
>      > The SoC supports EHCI companion interfaces, and my understanding is that
>      > it only has four physical USB ports. Does the real hardware instantiate
>      > separate EHCI and OHCI interfaces (for a total of 8 USB ports), or does it
>      > use the companion functionality ?
> 
>     Well, on the guest side you'll see 8 ports even when using the companion
>     functionality.  Each physical usb port has one ehci port (used when you
>     plug in usb 2.0+ devices) and one ohci port (used when you plug in usb
>     1.1 devices).
> 
>     The main difference is on the qemu backend side.  When using the
>     companion functionality you have a single qemu usb bus accepting both
>     1.1 and 2.0+ devices.  When not using the companion functionality you
>     have one usb bus accepting 2.0+ devices and another usb bus accepting
>     usb 1.1 devices ...
> 
>     The guest-visible difference is an per-port bit in ehci registers which
>     controls whenever ehci or the companion manages the device plugged in.
>     This bit exists for backward compatibility (guests without ehci driver
>     can manage all devices via ohci, with usb 2.0+ devices being downgraded
>     to 1.1 compatibility mode then).
> 
>      > If the real hardware only instantiates four USB ports (or, in other words,
>      > if it utilizes EHCI companion functionality), would it make sense to
>      > reflect that in qemu ?
> 
>     Yes.
> 
>     take care,
>        Gerd
> 
> 
> 
> -- 
> Niek Linnenbank
>