Re: [linux-usb-devel] CONFIG_USB_BANDWIDTH broken

Alan Stern
2005-12-26T03:58:46Z

On Sun, 25 Dec 2005, Lee Revell wrote:

> CONFIG_USB_BANDWIDTH breaks USB audio. This has been a problem for at
> least 6 months.
>
> Typical bug report:
>
> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=1642
>
> (search bug tracker for CONFIG_USB_BANDWIDTH to see many more)
>
> Is anyone working on fixing this?

The bug reports don't mention which USB host controller driver was being
used.

With ohci-hcd, bandwidth enforcement works okay.

With ehci-hcd, there are problems involved with scheduling
periodic transfers to a full-speed device connected through
a high-speed hub. These problems are slowly being fixed.

With uhci-hcd, bandwidth enforcement has never worked. New
changes to the driver (accepted just a few days ago) will
permit this to be fixed eventually. It might take a few months
(plus the time required for the changes to be added to the
official distribution kernel).

Alan Stern