Any interest in dwc-otg (aka dwc2) device emulation? For Raspi 3 and below.

Any interest in dwc-otg (aka dwc2) device emulation? For Raspi 3 and below.

[Paul Zimmerman]

Hi Folks,

I have been working on an emulation of the dwc-otg USB controller
(host mode only for now), as implemented on the Raspberry Pi 3 and
below, and on numerous other embedded platforms. I have it to a point
where it works pretty well with the dwc2 driver in the mainline Linux
kernel, and with the dwc-otg driver in the Raspbian kernel. Mouse and
keyboard work fine, and I *think* the usb-net device is working too,
although I have been unsuccessful in connecting to the outside world
with it.

I haven't done anything with gadget-mode yet, but that could certainly
be added in the future.

Would there be any interest in me submitting this for inclusion in
Qemu? I ask because I see there was a previous effort at this at
github.com/0xabu/qemu/hw/usb/bcm2835_usb.c, but it seems it never went
anywhere.

Thanks,
Paul

Re: Any interest in dwc-otg (aka dwc2) device emulation? For Raspi 3 and below.

[John Snow]

On 3/6/20 7:34 PM, Paul Zimmerman wrote:
> Hi Folks,
> 
> I have been working on an emulation of the dwc-otg USB controller
> (host mode only for now), as implemented on the Raspberry Pi 3 and
> below, and on numerous other embedded platforms. I have it to a point
> where it works pretty well with the dwc2 driver in the mainline Linux
> kernel, and with the dwc-otg driver in the Raspbian kernel. Mouse and
> keyboard work fine, and I *think* the usb-net device is working too,
> although I have been unsuccessful in connecting to the outside world
> with it.
> 
> I haven't done anything with gadget-mode yet, but that could certainly
> be added in the future.
> 
> Would there be any interest in me submitting this for inclusion in
> Qemu? I ask because I see there was a previous effort at this at
> github.com/0xabu/qemu/hw/usb/bcm2835_usb.c, but it seems it never went
> anywhere.
> 
> Thanks,
> Paul
> 

At a minimum, I think you should send your patches to the list for
posterity even if they don't wind up getting enough review pressure to
be merged.

If you want advice on how to split up your patches to entice more
reviewers, please let us know and any one of us can write a thousand
more :words: that might help make a better case.

(There's a much-too-long wiki entry on the matter, if you are brave.)

The issue, as always, is usually just reviewer time -- and how squeaky
the wheel is. Making the patches look pretty and well organized is one
way to trick well meaning people into reviewing your patches.

--js

Re: Any interest in dwc-otg (aka dwc2) device emulation? For Raspi 3 and below.

[Paul Zimmerman]

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Hi John,

Thanks for the tips! I found an issue when testing with the usb-storage
device, so I will work on fixing that, and then think about how best to
split up the patches.

Thanks,
Paul

On Mon, Mar 9, 2020 at 7:23 PM John Snow <jsnow@redhat.com> wrote:

>
>
> On 3/6/20 7:34 PM, Paul Zimmerman wrote:
> > Hi Folks,
> >
> > I have been working on an emulation of the dwc-otg USB controller
> > (host mode only for now), as implemented on the Raspberry Pi 3 and
> > below, and on numerous other embedded platforms. I have it to a point
> > where it works pretty well with the dwc2 driver in the mainline Linux
> > kernel, and with the dwc-otg driver in the Raspbian kernel. Mouse and
> > keyboard work fine, and I *think* the usb-net device is working too,
> > although I have been unsuccessful in connecting to the outside world
> > with it.
> >
> > I haven't done anything with gadget-mode yet, but that could certainly
> > be added in the future.
> >
> > Would there be any interest in me submitting this for inclusion in
> > Qemu? I ask because I see there was a previous effort at this at
> > github.com/0xabu/qemu/hw/usb/bcm2835_usb.c, but it seems it never went
> > anywhere.
> >
> > Thanks,
> > Paul
> >
>
> At a minimum, I think you should send your patches to the list for
> posterity even if they don't wind up getting enough review pressure to
> be merged.
>
> If you want advice on how to split up your patches to entice more
> reviewers, please let us know and any one of us can write a thousand
> more :words: that might help make a better case.
>
> (There's a much-too-long wiki entry on the matter, if you are brave.)
>
> The issue, as always, is usually just reviewer time -- and how squeaky
> the wheel is. Making the patches look pretty and well organized is one
> way to trick well meaning people into reviewing your patches.
>
> --js
>
>

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Re: Any interest in dwc-otg (aka dwc2) device emulation? For Raspi 3 and below.

[Peter Maydell]

On Sat, 7 Mar 2020 at 00:34, Paul Zimmerman <pauldzim@gmail.com> wrote:
>
> Hi Folks,
>
> I have been working on an emulation of the dwc-otg USB controller
> (host mode only for now), as implemented on the Raspberry Pi 3 and
> below, and on numerous other embedded platforms. I have it to a point
> where it works pretty well with the dwc2 driver in the mainline Linux
> kernel, and with the dwc-otg driver in the Raspbian kernel. Mouse and
> keyboard work fine, and I *think* the usb-net device is working too,
> although I have been unsuccessful in connecting to the outside world
> with it.

Do you have documentation of the hardware? One of the issues
we've had with this in the past is that we couldn't find the
hardare specs for the USB controller, so it was a bit difficult
to tell if a model of it was correct or not.

thanks
-- PMM

Re: Any interest in dwc-otg (aka dwc2) device emulation? For Raspi 3 and below.

[Stefan Hajnoczi]

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On Mon, Mar 09, 2020 at 08:15:33PM -0700, Paul Zimmerman wrote:
> Hi John,
> 
> Thanks for the tips! I found an issue when testing with the usb-storage
> device, so I will work on fixing that, and then think about how best to
> split up the patches.

Please CC Gerd Hoffmann (QEMU USB maintainer) when sending your patches.
Thanks!

Stefan

> 
> Thanks,
> Paul
> 
> On Mon, Mar 9, 2020 at 7:23 PM John Snow <jsnow@redhat.com> wrote:
> 
> >
> >
> > On 3/6/20 7:34 PM, Paul Zimmerman wrote:
> > > Hi Folks,
> > >
> > > I have been working on an emulation of the dwc-otg USB controller
> > > (host mode only for now), as implemented on the Raspberry Pi 3 and
> > > below, and on numerous other embedded platforms. I have it to a point
> > > where it works pretty well with the dwc2 driver in the mainline Linux
> > > kernel, and with the dwc-otg driver in the Raspbian kernel. Mouse and
> > > keyboard work fine, and I *think* the usb-net device is working too,
> > > although I have been unsuccessful in connecting to the outside world
> > > with it.
> > >
> > > I haven't done anything with gadget-mode yet, but that could certainly
> > > be added in the future.
> > >
> > > Would there be any interest in me submitting this for inclusion in
> > > Qemu? I ask because I see there was a previous effort at this at
> > > github.com/0xabu/qemu/hw/usb/bcm2835_usb.c, but it seems it never went
> > > anywhere.
> > >
> > > Thanks,
> > > Paul
> > >
> >
> > At a minimum, I think you should send your patches to the list for
> > posterity even if they don't wind up getting enough review pressure to
> > be merged.
> >
> > If you want advice on how to split up your patches to entice more
> > reviewers, please let us know and any one of us can write a thousand
> > more :words: that might help make a better case.
> >
> > (There's a much-too-long wiki entry on the matter, if you are brave.)
> >
> > The issue, as always, is usually just reviewer time -- and how squeaky
> > the wheel is. Making the patches look pretty and well organized is one
> > way to trick well meaning people into reviewing your patches.
> >
> > --js
> >
> >

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Re: Any interest in dwc-otg (aka dwc2) device emulation? For Raspi 3 and below.

[Paul Zimmerman]

Hi Peter,

I used to work for Synopsys, who is the vendor for the usb-otg IP, and
am the author of the dwc2 driver in the Linux kernel (actually just a
port of the vendor driver to Linux). So I am pretty familiar with the
hardware. But I had to give up all the documentation when I left
Synopsys. So, beyond what I could find on the web (register
description and programming model), I don't have any further
documentation.

Thanks,
Paul

On Tue, Mar 10, 2020 at 2:27 AM Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Sat, 7 Mar 2020 at 00:34, Paul Zimmerman <pauldzim@gmail.com> wrote:
> >
> > Hi Folks,
> >
> > I have been working on an emulation of the dwc-otg USB controller
> > (host mode only for now), as implemented on the Raspberry Pi 3 and
> > below, and on numerous other embedded platforms. I have it to a point
> > where it works pretty well with the dwc2 driver in the mainline Linux
> > kernel, and with the dwc-otg driver in the Raspbian kernel. Mouse and
> > keyboard work fine, and I *think* the usb-net device is working too,
> > although I have been unsuccessful in connecting to the outside world
> > with it.
>
> Do you have documentation of the hardware? One of the issues
> we've had with this in the past is that we couldn't find the
> hardare specs for the USB controller, so it was a bit difficult
> to tell if a model of it was correct or not.
>
> thanks
> -- PMM

Re: Any interest in dwc-otg (aka dwc2) device emulation? For Raspi 3 and below.

[John Snow]

On 3/10/20 3:00 PM, Paul Zimmerman wrote:
> Hi Peter,
> 
> I used to work for Synopsys, who is the vendor for the usb-otg IP, and
> am the author of the dwc2 driver in the Linux kernel (actually just a
> port of the vendor driver to Linux). So I am pretty familiar with the
> hardware. But I had to give up all the documentation when I left
> Synopsys. So, beyond what I could find on the web (register
> description and programming model), I don't have any further
> documentation.
> 
> Thanks,
> Paul
> 

That's awesome!

We don't always have specs for everything, but as many (public and
legal) references as you can spell out in your git commit messages, the
better, for the sake of maintainers who might need to audit changes in
the future (and don't have your expertise.)

Correlating things against the kernel driver will probably be plenty
good enough, I'd hope -- if the driver winds up having a bug against
real hardware we'd hope to see it in the wild, so it should be safe to
reference against.

(This is a bit of the snake eating its own tail but sometimes we just
don't have better.)

I wasn't aware you were the author of the kernel driver too. Now I'm
convinced it'd be a shame if you didn't at least post a v1!

--js