Re: [linux-usb-devel] Re: EHCI TT bandwidth (was Re: [PATCH]USB_BANDWIDTH documentation change)

[Lee Revell]

On Fri, 2005-12-30 at 14:13 -0500, Dan Streetman wrote:
> On Thu, 29 Dec 2005, Lee Revell wrote:
> 
> >How do I test them?  Should this make USB audio work with
> >CONFIG_USB_BANDWIDTH?
> 
> It won't have any effect on CONFIG_USB_BANDWIDTH, as the EHCI transaction 
> translator scheudling code doesn't care about that config setting.  This 
> also won't have any effect on USB 2.0 devices (e.g. a highspeed Audio 
> device).
> 
> The updates will only help in the situation where there are multiple
> lowpseed or fullspeed devices with periodic endpoints, all connected to
> the same USB 2.0 (highspeed) hub.  In that situation it's possible to
> "fill up" the USB 2.0 hub's transaction translator periodic schedule with
> only a few devices.  The updates allow many more devices to fit in the
> TT's periodic schedule.  The specific number of devices depends on how 
> many periodic endpoints, those endpoint's poll rates, and their max packet 
> sizes.
> 

OK.  For some reason I though that problem was fixed, I guess it was a
different issue.  ALSA users previously reported that a full speed audio
device didn't work at all through a high speed hub at all but that it
was fixed a few months ago.

Lee

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