Messages in this thread | | | Subject | Re: 2.6.11, USB: High latency? | From | Lee Revell <> | Date | Wed, 30 Mar 2005 19:51:05 -0500 |
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[cc list restored]
On Wed, 2005-03-30 at 14:57 -0800, David Brownell wrote: > Quoth rlevell@joe-job.com: > > I think this is connected to a problem people have been reporting on the > > Linux audio lists. With some USB chipsets, USB audio interfaces just > > don't work. There are dropouts even at very high latencies. > > Well, I'd not yet expect USB audio to work over EHCI quite yet, > though one of the patches Greg just posted should help some of > the issues with full speed iso through USB 2.0 hubs. (At least > for OUT transfers as to speakers.) >
This is the exact configuration of one of the users who reported the problem on LAU. Got a pointer to the patch? And what's the issue with IN transfers?
> You might consider reporting such issues on the Linux-USB list. > It's been ages since anyone reported such a bug with the OHCI > or UHCI drivers ... probably why folk have assumed there are > no problems there. >
OK, good to know.
> > Something to consider specifically with audio. That uses the > isochronous transfer mode, reserving USB bandwidth. But I've > certainly seen systems with PCI busses that are severely clogged, > so that the USB controllers have a hard time accessing main > memory. Even a perfectly functional USB stack will have a hard > time with such hardware!
Unlikely because it works under Windows. We're not all that far behind however; USB audio on that OS did not really work until XP SP1. Also, if that were a widespread problem we would be seeing problems with PCI devices too.
Also please fix the threading in your email client.
Lee
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