[ltp] Re: [ibm-acpi-devel] Recently identified ThinkPad mysteriouses

[Theodore Tso]

On Thu, Nov 22, 2007 at 03:20:11PM +0100, Thomas Renninger wrote:
> Hi Henrique,
> 
>  - Latest Lenovo ThinkPads do not like ACPI EC writes for brightness
>    switching (s2ram broken)
> 
>    I've been told it only happens when brightness is set above 7.
>    Don't know, but it seems to be the EC writes > 7 that lets the
>    machine not wake up anymore from a s2ram.

Define "latest Lenovo Thinkpads".  I have a X61s that doesn't seem to
have this problem.  Of course, according to www.lesswatts.org,
apparently the BIOS is just making pixels darker, and *not turning
down the backlight*, so it's not clear we want to be using this
interface anyway... (xbacklight is what we should be using).

>  - Weird USB - EHCI IRQ problems on very latest Lenovo models
> 
>    Unhandled IRQ messages. Looks like an IRQ (from camera?) gets routed
>    to EHCI pin also? Don't know the details and I am also not very
>    familar with this..., Oliver might be able to point you to bug
>    reports, AFAIK there also exist kernel.org bugs.
>    This is not solved yet, AFAIK.
>    If anyone knows more about this problem, that would be great...

It sounds like this problem:

   http://bugzilla.kernel.org/show_bug.cgi?id=8853

It seems to be related to the bluetooth driver.  See especially
comment #61 by Ben Herrenschmidt.  It mirrors what I am seeing on the
X61s almost exactly.  Fortunately the problem seems to be one that can
be worked around by unloading and reloading the ehci_hcd and uhci_hcd
modules.

>    Attaching an USB device breaks USB and throws a calltrace
>    https://bugzilla.novell.com/show_bug.cgi?id=325601

.... and it looks like the end of the Novell bugzilla also points the
finger at interrupt routing and bluetooth.  (Although interestingly, I
don't recall seeing a problem that would actually break the USB on
T60's; I'll have to check my old laptop and see if I see any evidence
of it.)

This smells very much like a ACPI DSDT bug; if Novell has access to
Lenovo engineers, I'd suggest seeking them out and reporting this as a
hardware bug.  (And if you could send updates to the kernel bugzilla
and/or Linux thinkpad list, I think we would all be grateful!)

       	     	      	      	       	     	 - Ted