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    SubjectRe: Cpufreq for opteron
    On Tue, Aug 26, 2003 at 07:43:37PM -0500, wrote:
    > > > + res = find_match(&targ, &min, &max,
    > > > + pol->policy ==
    > > : SEARCH_UP, 0,
    > > > + 0);
    > >
    > > Why do you check for CPUFREQ_POLICY here??? In a ->target
    > > class cpufreq
    > > driver[*] you must not worry about the policy, only about min and max
    > > frequency.
    > >
    > > [*] ->target class cpufreq drivers [cpufreq_driver->target is
    > > used] have
    > > specific operating frequencies.
    > > ->setpolicy class cpufreq drivers have operating frequency ranges
    > > [currently only available on Transmeta Crusoe processors]
    > If the driver has to expand the range to find a matching frequency, it
    > has to know whether to expand up or down. That comes from policy.

    No. A ->target class cpufreq driver doesn't care about policies. It cares
    about what the governor says [and "powersave" and "performance" are just
    special governors]. If a driver has to expand the range to find a matching
    frequency, it has to expand _up_. See
    drivers/cpufreq/freq_table.c::cpufreq_frequency_table_verify() and
    section 1.3 of Documentation/cpu-freq/cpu-drivers.txt:

    "You need to make sure that at least one valid frequency (or operating
    range) is within policy->min and policy->max. If necessary, increase
    policy->max fist, and only if this is no solution, decreas policy->min."

    Rationale for this is that cpufreq tries to guarantee at least policy->min
    processing power, independent of the chosen policy or governor.

    > I'll look into for the next rev.

    Section 2 of Documentation/cpu-freq/cpu-drivers.txt explains frequency table
    helpers - maybe that helps.

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