Re: Contacts within AMD? AMD-756 USB host-controller blacklisted due to

From: Miles Lane (miles@megapathdsl.net)
Date: Wed Apr 04 2001 - 16:40:51 EST


Joachim 'roh' Steiger wrote:

> i would like to help to track down this problem
> i'm using a gigabyte 7IXE revision 1.1
> kernel is 2.4.1
>
> lspci output for usb:
> 00:07.4 USB Controller: Advanced Micro Devices [AMD] AMD-756 [Viper] USB
> (rev 06) (prog-i
> f 10 [OHCI])
> Flags: bus master, medium devsel, latency 16, IRQ 11
> Memory at efffc000 (32-bit, non-prefetchable) [size=4K]
>
>
> On Wed, 4 Apr 2001, Miles Lane wrote:
>
>> Thomas Dodd wrote:
>>
>>
>>> Alan Cox wrote:
>>>
>>>
>>>> because we dont know the full scope of the problem yet.
>>>
>>> Exactly how many bug reports has this caused?
>>> What kind of problems?
>>
>
> here i only have this kernelmessage floating around in my logfiles about 1
> time the day:
>
> Apr 4 14:47:15 campari kernel: usb-ohci.c: bogus NDP=204 for OHCI
> usb-00:07.4
> Apr 4 14:47:15 campari kernel: usb-ohci.c: rereads as NDP=4
>
>
>> error." Most of the time, when the error occurs, it seems
>> pretty benign. That is, I haven't noticed it crashing USB
>> device connections, causing data corruption or OOPSen.
>> Some folks _have_ reported OOPSen, though, that seemed to
>> be triggered by the erratum #4 hardware bug. I think I
>> may have had one of these a long time ago.
>
>
> as you see it's revision 6
> i've had no other problems with usb for now and use this
> idVendor 0x046d Logitech Inc.
> idProduct 0xc00c
> usb-wheelmouse all the time
>
> i've never had this kernel or previous kernel (2.4.0test8) oopsen
> and it runs perfectly stable here
>
>
>> I believe David has found that there definitely are code
>> paths where this hardware bug can cause failures of various
>> sorts and that's why the AMD-756 has been blacklisted.
>
>
> since i did'nt cause any troubles here i would not like to have the
> complete AMD-756 blacklisted in the ohci-driver
> eventually only some revisions are that bad
>
> please correct me if i'm wrong i only don't want to blacklist complete
> chipset-series

Hi Joachim,

Personally, I agree with you, but I can also understand David's
desire to avoid wasting time chasing phantom bugs that only
show up due to this broken hardware. If it turns out that
there is actually a well-defined workaround that AMD will
tell us about, it shouldn't take too long before we have a
real fix and the AMD-756 can be taken off of the blacklist.

My guess is that there are specific drivers for which this
hardware bug causes problems. You probably just aren't
using the *right* drivers. :-)

Luckily, USB add-on cards are pretty cheap, so I suppose you
could just put a new host-controller in your test machine
for a month or two until David and Alan get this sorted out
with AMD. Think of it this way, you'll have more hardware
configurations to test with, so get a UHCI or EHCI card.
Woohoo! (Only half kidding)

        Miles

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This archive was generated by hypermail 2b29 : Sat Apr 07 2001 - 21:00:15 EST