linux-kernel - Re: [PATCH v2 7/20] clk: sunxi-ng: mux: Re-adjust parent rate

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Message-ID: <CAGb2v66U8xKn0QrvOkqGUniyJ0Uus-9kGL5opSu9xzJ6h8QE8g@mail.gmail.com>
Date:   Thu, 4 May 2017 11:28:24 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:     Mike Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH v2 7/20] clk: sunxi-ng: mux: Re-adjust parent rate

On Wed, May 3, 2017 at 7:59 PM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
> Currently, the parent rate given back to the clock framework in our
> request is the original parent rate we calculated before trying to round
> the rate of our clock.
>
> This works fine unless our clock also changes its parent rate, in which
> case we will simply ignore that change and still use the previous parent
> rate.
>
> Create a new function to re-adjust the parent rate to take the pre-dividers
> into account, and give that back to the clock framework.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
> ---
>  drivers/clk/sunxi-ng/ccu_mux.c | 33 ++++++++++++++++++++++++++++-----
>  1 file changed, 28 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/clk/sunxi-ng/ccu_mux.c b/drivers/clk/sunxi-ng/ccu_mux.c
> index c33210972581..1ce62cc23f8a 100644
> --- a/drivers/clk/sunxi-ng/ccu_mux.c
> +++ b/drivers/clk/sunxi-ng/ccu_mux.c
> @@ -64,6 +64,14 @@ unsigned long ccu_mux_helper_apply_prediv(struct ccu_common *common,
>         return parent_rate / ccu_mux_get_prediv(common, cm, parent_index);
>  }
>
> +unsigned long ccu_mux_helper_unapply_prediv(struct ccu_common *common,
> +                                           struct ccu_mux_internal *cm,
> +                                           int parent_index,
> +                                           unsigned long parent_rate)
> +{
> +       return parent_rate * ccu_mux_get_prediv(common, cm, parent_index);
> +}
> +
>  int ccu_mux_helper_determine_rate(struct ccu_common *common,
>                                   struct ccu_mux_internal *cm,
>                                   struct clk_rate_request *req,
> @@ -89,22 +97,37 @@ int ccu_mux_helper_determine_rate(struct ccu_common *common,
>                 best_rate = round(cm, best_parent, &adj_parent_rate,
>                                   req->rate, data);
>
> +               /*
> +                * parent_rate might have been modified by our clock.
> +                * Re-apply the pre-divider if there's one, and give

Might want to reword the comments to match the new name.

> +                * the actual frequency the parent needs to run at.
> +                */
> +               best_parent_rate = ccu_mux_helper_unapply_prediv(common, cm, -1,
> +                                                                adj_parent_rate);
> +
>                 goto out;
>         }
>
>         for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
> -               unsigned long tmp_rate, parent_rate, adj_parent_rate;
> +               unsigned long tmp_rate, parent_rate;
>                 struct clk_hw *parent;
>
>                 parent = clk_hw_get_parent_by_index(hw, i);
>                 if (!parent)
>                         continue;
>
> -               parent_rate = clk_hw_get_rate(parent);
> -               adj_parent_rate = ccu_mux_helper_apply_prediv(common, cm, i,
> -                                                             parent_rate);
> +               parent_rate = ccu_mux_helper_apply_prediv(common, cm, i,
> +                                                         clk_hw_get_rate(parent));
> +
> +               tmp_rate = round(cm, parent, &parent_rate, req->rate, data);
>
> -               tmp_rate = round(cm, parent, &adj_parent_rate, req->rate, data);
> +               /*
> +                * parent_rate might have been modified by our clock.
> +                * Re-apply the pre-divider if there's one, and give

Same here. Otherwise,

Acked-by: Chen-Yu Tsai <wens@...e.org>

> +                * the actual frequency the parent needs to run at.
> +                */
> +               parent_rate = ccu_mux_helper_unapply_prediv(common, cm, i,
> +                                                           parent_rate);
>                 if (tmp_rate == req->rate) {
>                         best_parent = parent;
>                         best_parent_rate = parent_rate;
> --
> git-series 0.8.11