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    SubjectRe: [PATCH v3 2/3] clk: divider: Switch from .round_rate to .determine_rate by default
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    Hi

    On 02.07.2021 11:19, Martin Blumenstingl wrote:
    > Hi Stephen,
    >
    > On Fri, Jul 2, 2021 at 3:02 AM Stephen Boyd <sboyd@kernel.org> wrote:
    > [...]
    >> My guess is that we have drivers copying the clk_ops from the
    >> divider_ops structure and so they are copying over round_rate but not
    >> determine_rate.
    > I just learned something new - thanks for investigating this as well!
    >
    > $ git grep "clk_divider_ops\.round_rate" drivers/
    > drivers/clk/bcm/clk-bcm2835.c: return clk_divider_ops.round_rate(hw,
    > rate, parent_rate);

    I confirm that this issue appears also on Raspberry Pi 3b+ board. I was
    about to write a bug report, but you were faster. The funny thing is
    that is so nondeterministic, that automated bisecting failed to catch it.

    > drivers/clk/clk-stm32f4.c: return clk_divider_ops.round_rate(hw,
    > rate, prate);
    > drivers/clk/clk-stm32h7.c: return clk_divider_ops.round_rate(hw,
    > rate, prate);
    > drivers/clk/clk-stm32mp1.c: req->rate =
    > clk_divider_ops.round_rate(hw, req->rate, &best_parent_rate);
    > drivers/clk/imx/clk-divider-gate.c: return
    > clk_divider_ops.round_rate(hw, rate, prate);
    > $ git grep "clk_divider_ro_ops\.round_rate" drivers/
    > $
    >
    > Changing these over to use clk_divider_ops.determine_rate doesn't seem too hard.
    > The part that I am not sure about is how to organize the patches.
    > 1) amend the changes to all relevant drivers (from above) to this patch
    > 2) multiple patches:
    > - adding .determine_rate to the default divider ops (but not removing
    > .round_rate)
    > - a single patch for each relevant driver (from above)
    > - removing .round_rate from the default divider ops
    >
    > Another approach is to first create clk_divider_determine_rate() (as
    > done here) and export it.
    > Then I could have one individual patch for each relevant driver (from
    > above) to use:
    > .determine_rate = clk_divider_determine_rate,
    > Then finally I could remove clk_divider_round_rate() and switch over
    > the default divider ops to .determine_rate as well.
    >
    > Which way do you prefer?
    >
    >
    > Best regards,
    > Martin
    >
    Best regards
    --
    Marek Szyprowski, PhD
    Samsung R&D Institute Poland

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