Question about error from xhci-hcd

From: Larry Finger
Date: Sat Oct 29 2011 - 13:47:57 EST


Pardon the intrusion, but I'm trying to fix a problem for v4mp, a user of the rtl8192cu driver on an Alfa AWUS036NHR. I have one of the devices, and it works on a USB 2.0 hub, but fails with 3.0 hardware with lots of

xhci_hcd 0000:05:00.0: ERROR no room on ep ring

messages logged.

The device works with an out-of-kernel driver available from the Alfa or Realtek web sites, but I want to fix rtl8192cu.

What condition leads to the above message? The user's dmesg buffer has wrapped, thus I don't see the beginning of the failure. He is using a canned distro kernel, thus he cannot include any extra debugging info such as a stack dump when the errors occur. As he uses the compat-wireless package, I think I can incorporate a new copy of xhci-hcd with it, but I have not done so yet.

Thanks for any help you can give,


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