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    SubjectRe: [RFC] Dynamic fan clock divider changes (long)
    > > The user still doesn't have to care, which is fine, but if the user
    > > has a fan speed between 2000 and 5000 RPM, with low limit set to
    > > 1500 RPM, he/she will have a "bad" accuracy at 5000 RPM (+/- 104
    > > RPM). I see this as the low limit "nailing" the divider ;)
    > This doesn't sound so bad at all. And this seems to be the simplest
    > approach.


    > > This is what I implemented in my new pc87360 driver (after trying
    > > #1). I use 85 and 224 as the arbitrary limits for changing
    > > dividers.
    > This confused me a bit. It seems that a direct consequence of
    > implementation #2 is that the divider will be set in a way that the
    > low limit will be between 128 and 255, and that there is no point in
    > changing the divider, because it will only get worse.

    You're absolutely right.

    > This leads directly to implementation #4. Am I missing something?

    You are. In #4, the divider is arbitrarily chosen by "us", regardless of
    the user's setup. In #2, the divider is chosen according to the user's
    hardware and fan use. The common point is that (after setting the low
    limit for #2) the divider will no longer change (until the low limit
    changes for #2). But in #2 the divider is optimal, in #4 it is

    This makes a big difference because we cannot possibly arbitrarily pick
    a divider and not allow the user to change it, so in #4 we would have to
    keep the manual interface as well, as it exists for now. For #2, we can
    reasonably hope to get rid of the manual interface after some times
    (once the automatic mode will have been tested and is believed to be

    > Anyway, if the user is really concerned about accuracy an average of
    > several measurements should increase precision in this kind of
    > problem.

    Yes, that's a possibility. Not sure it's even worth the extra code, but
    someone motivated could do it, you're right.

    Thanks for your comments :)

    Jean Delvare
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