libpayload: Use interrupt transfers for USB hubs

In interactive payloads, the USB stack's poll procedure is implicitly
called from the UI loop. Since all USB control transfers are handled
synchronously, polling hubs with these slows the UI significantly down.

So switch to interrupt transfers that are done asynchronously and only
perform control transfers when the hub reported a status change.

We use the interrupt endpoint's max packet size instead of the theo-
retical transfer length of `(bNrPorts + 1) / 8` as Linux' code mentions
hubs that return too much data.

Change-Id: I5af02d63e4b8e1451b160b77f3611b93658a7a48
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/18499
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

0 files changed, 0 insertions, 0 deletions