Messages in this thread | | | Date | Sun, 30 Oct 2011 10:30:24 -0500 | From | Larry Finger <> | Subject | Re: Question about error from xhci-hcd |
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On 10/30/2011 12:04 AM, Sarah Sharp wrote: > On Sat, Oct 29, 2011 at 12:48:12PM -0500, Larry Finger wrote: >> Sarah, >> >> 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 xHCI driver allocates a fixed-size endpoint ring, and only so much > data can fit on it. If the driver is allocating many URBs or many URBs > with a lot of data, then you will see these messages and the URBs will > fail to be submitted. Now if neither of those conditions are true, then > it's possible we just have a bug in the xHCI driver. > > There is a patchset in the works to dynamically expand the endpoint > rings, but it's still going through revisions: > > http://marc.info/?l=linux-usb&m=131918645424329&w=2
Thanks for the link. I'll look into that patch set and also examine the number of URBs that the driver is submitting.
> It might be done for the 3.3 kernel, but until then the driver is just > going to be broken, sorry. :(
No problem.
>> 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. > > Which distro? Several of the distros are based on 2.6.32, which only > had minimal support for xHCI. Updating just the xHCI driver with a > more recent one isn't going to be possible with that old of a kernel, > since later changes also touched the USB core as well.
He is running the 3.1-rc9 kernel from Ubuntu. We should have no problems updating xHCI. I did add it to the compat-wireless package and sent the code to him, but have not heard back. I will try to add the new patch series to see if that helps.
Thanks for your help,
Larry
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