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From:   Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date:   Fri, 2 Jul 2021 11:19:37 +0200
Message-ID: <CAFBinCAASQUB=cg5EFsBQ4jd3TvcCJzV1=sYJci4ibR7FjRcww@mail.gmail.com>
Subject: Re: [PATCH v3 2/3] clk: divider: Switch from .round_rate to
 .determine_rate by default
To:     Stephen Boyd <sboyd@kernel.org>
Cc:     Guenter Roeck <linux@roeck-us.net>, mturquette@baylibre.com,
        linux-clk@vger.kernel.org,
        Neil Armstrong <narmstrong@baylibre.com>, jbrunet@baylibre.com,
        khilman@baylibre.com, linux-kernel@vger.kernel.org,
        linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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);
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