Re: Identifying Synopsys USB3 Controller on Baytrail Device

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On Mon, Feb 09, 2015 at 10:27:53AM -0600, Felipe Balbi wrote:
> Hi,

Hi,

> 
> On Sun, Feb 08, 2015 at 02:51:16PM -0700, Joseph Kogut wrote:
> > I have an Intel Valleyview/Baytrail based device (specifically a Dell
> > Venue 8 Pro 5830) that I'd like to be able to use the Linux Gadget
> > subsystem on, but it seems that the controller isn't currently
> > supported. I'm running the 3.19rc7 mainline release.
> > 
> > The device has a micro AB connector. Based on my experiences with a
> > similar (Merrifield) platform using Intel's own out of tree patchset
> > that had working DRD support using a modified DWC3 driver, I suspected
> > that the Baytrail platform I'm working on would also use the DWC3
> > driver.
> > 
> > The output of "lspci -nn" shows:
> > 
> > > 00:14.0 USB controller [0c03]: Intel Corporation Atom Processor
> > > Z36xxx/Z37xxx Series USB xHCI [8086:0f35] (rev 09)
> 
> hmm... looking at what we support today we for PCI, we support Baytrail,
> Merrifield, SPTLP, SPTH, BSW (whatever these last three are) and AMD NL.
> 
> However Baytrail is reported as 0x0f37, not 0x0f35. If you have a
> micro-AB and then it ought to support peripheral mode.
> 
> I have a feeling the problem you're having is the same David Cohen (in
> Cc) has been trying to support upstream. The SoC has two controllers
> inside, one is peripheral only while the other is host only; there's
> discrete mux in front of them to mux the data lines to one or the other
> controller.
> 
> David, is this what's going on ?

I don't have deep knowledge about this hardware, but after a quick look
at internet it seems to be in similar case of Asus T100: The micro AB
connector is used for charging only.
Since it's BYT SoC, it sure has DWC3 controller. But it doesn't mean the
micro AB connector reaches it.

Br, David

> 
> > Also, a string in the ACPI table tells me that the device uses a
> > Synopsys XHCI core, though I'm not sure if it's DRD capable, or host
> > only.
> > 
> > > _DDN.Baytrail XHCI controller (Synopsys core/OTG)
> > 
> > 
> > I tried adding the controller's PCI ID to drivers/usb/dwc3/dwc3-pci.c,
> > and upon rebooting, the DWC3 module loaded, but reported:
> > 
> > > [    5.962605] dwc3 dwc3.0.auto: this is not a DesignWare USB3 DRD Core
> > 
> > 
> > I don't know if this is the result of Dell messing with the ACPI
> > table, as they seem prone to do, making the otherwise compatible
> > hardware undetected by the proper driver, or if I'm just barking up
> > the wrong tree. I think it's premature to file a bug report,
> > considering the fact that I'm not yet sure this controller uses the
> > DWC3 core.
> > 
> > Attached is the acpi dump from the device in question.
> > 
> > Thank you for your time,
> > Joseph
> 
> 
> 
> -- 
> balbi


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