Re: 2.6.16-rc5: known regressions [TP 600X S3, vanilla DSDT]

[Sanjoy Mahajan <sanjoy@mrao.cam.ac.uk>]

> If you do it in this way, all thermal zone's _TMP will be faked.

Loading 'thermal' with zone_to_keep=0 meant that it skipped THM{2,6,7}
(the only other zones).  But only THM0 was loaded, so any path that
included, say, THM2._TMP wouldn't get executed because of lines like:

     if (!tz)
	return_VALUE(-EINVAL);

Plus the dmesgs show all cases when _TMP was faked (each fakery
produces a printk).  In the experiment with zone_to_keep=0, the only
cases were with THM0.

> If you remove the real THM0._TMP, and fake a dummy THM0._TMP in
> DSDT, and don't change anything in kernel, then if S3 works well, I
> will be convinced that THM0._TMP was causing trouble.

I'll try it, to test my theory above!  But one clarification first: Do
you mean that I use a vanilla thermal.c, or should I keep using the
modified thermal.c with zone_to_keep=0 as the module parameter?  I
don't think I revert to the vanilla thermal.c.  Suppose that there are
two bugs, which I think is likely (see previous email).  Commenting
out only THM0._TMP but preserving everything else in the DSDT & kernel
might eliminate any bug caused by THM0._TMP.  But if it still hangs --
and I'm pretty sure it will -- it means there's a another bug
somewhere else.

Here's why I'm sure it will hang.  When I commented out all
evaluations of _TMP (modifying utils.c), but used a vanilla thermal.c,
it still hung.  And commenting out all _TMP's means I commented out
THM0._TMP.  So vanilla thermal.c + no THM0._TMP should hang too.

> Ok, Let's change the way of hacking. Let's start bisection without
> touching kernel, instead with DSDT.

No problem I think.

> Firstly, you need to find out which THM.

The zone_to_keep=0 tests show that THM0 causes a problem, don't they?
Other zones may also cause a problem, but THM0 can do it all alone.

> Then, which Methods.  

The test that hung on the first S3 sleep, with zone_to_keep=0 and
bisect_get_info=1, shows that just THM0._TMP can cause a problem --
since no other methods got executed.

As with figuring out which zones cause problems, other methods may
also cause the problem.  So I want to make sure I use a bisection
method that will work even if there is more than one bug, whether in
multiple zones or in multiple methods in the same zone.

-Sanjoy

`Never underestimate the evil of which men of power are capable.'
         --Bertrand Russell, _War Crimes in Vietnam_, chapter 1.
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