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    SubjectRe: MCP limit log messages, 2.6.36-rc4
    On 09/24/2010 05:54 AM, Jesse Barnes wrote:
    > On Thu, 23 Sep 2010 13:48:16 -0700
    > Jesse Barnes<jbarnes@virtuousgeek.org> wrote:
    >
    >> On Wed, 15 Sep 2010 11:47:45 -0600
    >> Tim Gardner<tim.gardner@canonical.com> 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@canonical.com


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