Re: [LAU] Intel Rate Matching Hub and USB soundcards

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To: Linux Audio Users <linux-audio-user@...>
Date: Sunday, June 13, 2010 - 1:24 pm

Jeremy Jongepier wrote:

The "Rate Matching" behaves just like a normal USB hub; this design
choice does not introduce any problems by itself.

However, the USB controllers in these chipsets (5 and 3400 series) are
just plain buggy; the bug list ("specification update") says:
| 6. Intel® 5 Series Chipset and Intel® 3400 Series Chipset Full-Speed
| USB Isochronous Packet Truncation
|
| Problem: Full-Speed isochronous-out transactions with multi-frame
| packets may be truncated, in the presence of Full or Low-Speed USB
| asynchronous transactions.
| • For this to occur, two devices, one performing Full-Speed
| isochronous-out transactions and one performing asynchronous
| transactions must be connected to the same USB controller
| (Ports 0-7 and 8-13).
|
| Implication: In the case of a USB audio device this issue may result
| in no audible impact or audible artifacts such as pops and clicks.
|
| Note:
| • High-Speed and Low-Speed USB devices are not impacted by this issue.
| • Only devices supporting Full-Speed isochronous-out transactions that
| Intel is aware of are audio devices, such as sound adapters,
| speakers, and headphones.
| • Intel has only observed the issue when a Full-Speed audio devices
| and Full-Speed USB web camera are connected to the same USB
| controller.
|
| Workaround: None.
| Status: Fixed

(that is, fixed in chip revision B3)

Regards,
Clemens
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Messages in current thread:
[LAU] Intel Rate Matching Hub and USB soundcards, Jeremy Jongepier, (Sat Jun 12, 12:34 pm)
Re: [LAU] Intel Rate Matching Hub and USB soundcards, Clemens Ladisch, (Sun Jun 13, 1:24 pm)
Re: [LAU] Intel Rate Matching Hub and USB soundcards, Jeremy Jongepier, (Mon Jun 14, 7:55 am)