[edk2-devel] USB isochronous transfers

[Michael D Kinney]

PEI use of USB is usually limited to access to recovery images from media devices.

I would recommend focusing on UEFI components,

Mike


> -----Original Message-----
> From: devel at edk2.groups.io <devel at edk2.groups.io> On Behalf Of Ethin Probst
> Sent: Tuesday, July 20, 2021 8:33 AM
> To: devel at edk2.groups.io
> Cc: Leif Lindholm (Nuvia address) <leif at nuviainc.com>; Andrew Fish <afish at apple.com>; Ni, Ray <ray.ni at intel.com>
> Subject: [edk2-devel] USB isochronous transfers
> 
> Hello all,
> 
> A few days ago Leif determined that the USB DXE does not implement
> isochronous transfers. This will make USB Audio quite impossible as
> the audio data endpoint requires isochronous transfers.
> 
> I was looking at the EHCI driver but I can't determine a couple things:
> 
> - Isochronous transfers have a different structure compared to other
> URB types. (Each URB type may have its own structure -- I haven't
> checked.)
> - I can't seem to figure out how this is handled in, say, EhciDxe.
> - If we were to try and implement this -- though I'm not quite sure
> how -- would we need to modify the PEIs too?
> 
> --
> Signed,
> Ethin D. Probst
> 
> 
> 
> 



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