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Old 07-02-10, 03:04 AM   #17
zbiggy
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Join Date: Sep 2002
Posts: 623
Default Re: Geforce 8200 users, I need your help with finding usb hanging issue

In my opinion there is hardware chipset bug at usb ohci silicon part in Nvidia MCP78S chipset (trade names: Geforce 8200, nForce 730a, probably all nforce7 family). Nvidia did not detect it at manufacturing time because they test chipsets only with windows which do not use hardware so efficiently like Linux. MCP78S ohci usb controller hiccups during transfer few times every 2 minutes. On Linux some of this hiccups hang usb. Windows is slower and dumber so only 1 second distortion can be heard when using usb 1.1 audio card and hang does not occur.

To fix this bug we have to make Linux slower and dumber like Windows when servicing usb ohci. I have done some initial work this way and I created patch which improves (but not fixes yet) usb on Geforce 8200. If you are able to compile kernel from sources I can send it here when I come back home (~15 hours counting since now).

On my machine usb hangs after few minutes of use. After applying patch after few hours or not at all if I will not overload usb with huge data transfers.
This makes working medium traffic devices (usb storages, adsl modems).
If you have problems with usb audio or movie camera the patch will not help because these devices put on usb continuous big transfer of data. Of course you can always try.
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