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From: "Ethin Probst" <harlydavidsen@gmail.com>
Date: Tue, 20 Jul 2021 10:32:59 -0500
Message-ID: <CAJQtwF1eO6LqX6hE0vxjq45x_4fF4UD4_PdnF1kZZwwk5G6Few@mail.gmail.com>
Subject: USB isochronous transfers
To: devel@edk2.groups.io
Cc: "Leif Lindholm (Nuvia address)" <leif@nuviainc.com>, Andrew Fish <afish@apple.com>, Ray Ni <ray.ni@intel.com>
Content-Type: text/plain; charset="UTF-8"

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