Re: Problem of initialization of platform-ehci-usb in sbsa-ref

[Gerd Hoffmann]

  Hi,

> Gerd, is there a particular reason our EHCI controller only
> claims to be able to do 32-bit DMA ? Should we give it a QOM
> property so boards that only have RAM above the 4GB mark can
> use it ? (Would the x86 PC benefit from allowing >4GB DMA?)

Can be done, but it's more complex than just a property.  All
the EHCI descriptors exist in two variants, one for 32bit and
one for 64bit.  The current code base only supports the 32bit
versions.

Alternatives:
  (a) use an iommu to map 32bit to 64bit dma addresses.
  (b) use xhci instead of ehci.

I'd recommend (b) as the xhci hardware design is much more
virtualization-friendly.

take care,
  Gerd