Re: MCP limit log messages, 2.6.36-rc4

[Tim Gardner]

On 09/24/2010 05:54 AM, Jesse Barnes wrote:
> On Thu, 23 Sep 2010 13:48:16 -0700
> Jesse Barnes<jbarnes@xxxxxxxxxxxxxxxx>  wrote:
>
> > On Wed, 15 Sep 2010 11:47:45 -0600
> > Tim Gardner<tim.gardner@xxxxxxxxxxxxx>  wrote:
> >
> > > I've been getting regular MCP limit log messages on a Dell Studio 1458
> > > (i5 CPU) with an A02 BIOS. With the attached debug hack it prints the
> > > following values:
> > >
> > > [   33.605098] intel ips 0000:00:1f.6: MCP limit exceeded: Avg power
> > > 30123, limit 1023
> > > [   38.597998] intel ips 0000:00:1f.6: MCP limit exceeded: Avg power
> > > 21697, limit 1023
> > > [   43.590917] intel ips 0000:00:1f.6: MCP limit exceeded: Avg power
> > > 15390, limit 1023
> > > [   48.583821] intel ips 0000:00:1f.6: MCP limit exceeded: Avg power
> > > 43370, limit 1023
> > > [   53.576740] intel ips 0000:00:1f.6: MCP limit exceeded: Avg power
> > > 64728, limit 1023
> > >
> > > This is an idle machine which starts printing these messages about 30
> > > seconds after boot. Any thoughts?
> >
> > Actually, it looks like you have some non-upstream patches to the IPS
> > driver, maybe one of Joe's patches to add more debug output when limits
> > are exceeded?

Its just a debug hack which I wrote (that I mentioned in the first 
email) so I could figure out why the driver was complaining.

> > At any rate, I think we're setting the MCP power limit incorrectly.
> > The BIOS must be giving us a limit in 0.1W units (though even then it
> > looks bogus); we need to clamp it to one of the available defaults.
> >
> > Joe has some code for that as well, I've just asked him to update his
> > patch, which we should get into 2.6.35.x.
>
> Just posted some fixes for this to the x86 driver list, in particular
> the "[PATCH 2/2] IPS driver: verify BIOS provided limits" should help a
> bit here, but I still have a bug to fix in the i915 driver to really
> make things work.

I'll be back from Asia by Monday and will give these patches a try.

rtg
--
Tim Gardner tim.gardner@xxxxxxxxxxxxx
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