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SubjectRe: Intel P55 Chipset BUG [usbhid-raw/devices/broken?] [tested 3 different UPS']

On Sun, 1 Nov 2009, Matthew Dharm wrote:

> On Sun, Nov 01, 2009 at 12:11:44PM -0500, Alan Stern wrote:
>> On Sat, 31 Oct 2009, Justin Piszcz wrote:
>>> 1. 5 minutes of usbmon output on via chipset [working]
>>> 2. 5 minutes of usbmon output on intel p55 usb chipset [ehci/not working]
>> To summarize the differences between the logs, the Intel controller
>> shows occasional instances of failed transfers like this:
>> ffff8802138c8500 3487005687 S Ci:2:004:0 s 81 06 2100 0000 0009 9 <
>> ffff8802138c8500 3487006051 C Ci:2:004:0 -32 0
>> while the corresponding transfers worked with the VIA controller:
>> ffff88020c46dd40 1774844264 S Ci:4:002:0 s 81 06 2100 0000 0009 9 <
>> ffff88020c46dd40 1774855248 C Ci:4:002:0 0 9 = 09211001 21012237 04
>> and indeed they worked in the other Intel logs (the failures appeared
>> to be more or less at random).
>> This does indeed look like a low-level hardware problem, but I'm
>> hesitant to blame it on the chipset. For example, the problem might
>> lie in the hub you've got between the UPS and the computer. I know,
>> this doesn't explain why everything works okay with the VIA controller.
>> Probably the only way to tell for sure what's really happening is by
>> using an expensive bus analyzer.
>> Have you tried bypassing that hub, and plugging the UPS directly into
>> the computer?


I do not use any hubs in this environment, everything is directly
attached to the motheboard. Per Matthew (noted below) when I
mention hub I am talking about your typical USB hub one would
attach to a USB port on the board, not the integrated one on the
motherboard. Everything is directly attached from the motherboard
to each respective device.

MOBO -> etc

> I think P55 chipset has an integrated hub, which is not removeable. The
> only USB controller is EHCI, and that is connected directly to a hub in the
> silicon which provides multiple downstream ports and does the translation
> to 1.0 speeds. So the hub cannot be bypassed.
> Two things to note:
> 1) Not all ports on that silicon are the same. Specifically, ports 1 and 9
> have special properties (related to USB-based debugging). You should try
> other ports (note that I count ports starting at 0).
I have tested every port on the motherboard (the 8 on the back and 4 off
of the USB headers on the motherboard):

The problem occurred on every port.

> 2) I noticed this article:
> -- this may
> suggest that there are other issues with P55 chipset and USB. According to
> this article, as with this reported issue, adding an external USB hub
> doesn't help, but an add-in PCI USB card does. We may have to consider a
> P55 issue as a possibility here.
Very interesting-- the C-state option for the CPU is on/enabled in the
BIOS, it has always remained on, I never disabled it.


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