On Tue, 9 Jul 2013, Felipe Balbi wrote:
> Hi,
>
> On Mon, Jul 08, 2013 at 09:55:15PM -0700, Sarah Sharp wrote:
> > Xenia, I'm not sure what you mean by "the xHC controller and the host
> > support
> > 64 bit DMA addresses". The xHC controller is the xHCI host. Did you maybe
> > mean "If both the xHCI host and the system support 64-bit DMA"?
I bet Xenia meant "the xHC controller and the host system".
> > I'm also a bit confused as to why the platform device code could work at
> > all in the current state. Xenia's patch sets usb_hcd->self.uses_dma.
> > The xHCI platform code currently doesn't set this flag. The xHCI driver
> > also doesn't set the HCD_LOCAL_MEM flag. So what the heck happens with
> > a platform device without either of those flags set in this code:
> >
...
> > As far as I can tell, that means the setup packet for control transfers
> > doesn't actually get mapped for DMA currently. With Xenia's patch it
> > will.
>
> That's a very good finding and I don't know how come we never triggered
> it. I am sure we have OMAP5 working with that :-s
It's because of this line in usb_create_shared_hcd():
hcd->self.uses_dma = (dev->dma_mask != NULL);
As a result, HCDs shouldn't have to set this flag themselves.
Alan Stern
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