[Bug 51847] p4-clockmod and "N60 errata" patch

[Paolo Grifa]

Public bug reported:

Binary package hint: linux-image-2.6-386

Clock modulation in Pentium IV no longer scale under 2 Ghz. This patch was introduced in Breezy for a bug in Pentium IV (N60 errata) that made pc to hang when arriving at the slowest possible frequency.
The problem is that this patch doesn't allow to go under 2 Ghz, that is a frequency far too high for every computer. Infact in the file p4-clockmod.c you can find at line 250:

if (has_N60_errata[policy->cpu] && p4clockmod_table[i].frequency <
2000000)

This problem can be considered as a bug since it is really not necessary
not to go under 2 Ghz and on laptops it means that it consumes a lot
more energy and cpu gets much hotter while fan is always on. It would be
much more efficient a value like 700000 (0,7 Ghz) or even less, since
there aren't any cpu which lowest frequency is under 0,4 Ghz).

The line should be:

if (has_N60_errata[policy->cpu] && p4clockmod_table[i].frequency <
700000)

** Affects: linux-meta (Ubuntu)
     Importance: Untriaged
         Status: Unconfirmed

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p4-clockmod and "N60 errata" patch
https://launchpad.net/bugs/51847