Re: [PATCH v1 0/9] Support UDC on Tegra 20/30/114/124

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On Thu, Jul 06, 2017 at 02:20:04AM +0300, Dmitry Osipenko wrote:
> On 06.07.2017 01:54, Stephen Warren wrote:
> > On 07/05/2017 04:13 PM, Dmitry Osipenko wrote:
> >> On 05.07.2017 23:31, Stephen Warren wrote:
> >>> On 07/05/2017 11:19 AM, Dmitry Osipenko wrote:
> >>>> Some time ago Thierry Reding sent out patches that enabled UDC on NVIDIA
> >>>> Tegra, unfortunately they haven't got enough traction to get into the
> >>>> kernel. I've rebased those patches and added a fix for the Ethernet USB
> >>>> Gadget on Tegra20, Marc Dietrich tested UDC driver on AC100 and Nicolas
> >>>> Chauvet on TK1. Like an original patchset, this series adds support for
> >>>> the peripheral mode only.
> >>>
> >>> Does this mean that the relevant ports no longer support host mode? That's going
> >>> to be a user-visible regression, which doesn't sound like a good idea. Isn't OTG
> >>> possible instead?
> >>
> >> We are going to switch only AC100 and TrimSlice to use the UDC driver.
> > 
> > Really? I saw patches in the series for Beaver, Dalmore, and Jetson TK1 too.
> > 
> 
> Yes, the "PHY" and "EHCI" nodes are disabled on those boards in DT.
> 
> >> Do you
> >> know whether that port is working in a host mode with the tegra-ehci driver on
> >> these devices?
> > 
> > If any USB port is enabled in the DT, it was certainly validated at some point.
> > IIRC, we only have host mode enabled at present. So, yes, I'd expect this port
> > to work in host mode currently without any issue.
> > 
> 
> Okay, so we have to decide whether it's reasonable to switch AC100 and TrimSlice
> to the peripheral mode. I think realistically chances that someone uses that
> port in a host mode are quite low, while it works fine and probably more useful
> in a device mode.

Judging by this:

	http://trimslice.com/download/documentation/trim-slice-man.pdf

at least TrimSlice doesn't seem to implement OTG, so we'd have to make a
choice to support either host or peripheral mode. I guess technically it
would need to be peripheral mode because pin 4 is not connected.

Does a similar document exist for AC100?

Thierry

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