Date:   Wed, 3 May 2017 20:53:33 +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 1/20] clk: divider: Make divider_round_rate take the
 parent clock

On Wed, May 3, 2017 at 7:59 PM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
> So far, divider_round_rate only considers the parent clock returned by
> clk_hw_get_parent.
>
> This works fine on clocks that have a single parents, this doesn't work on
> muxes, since we will only consider the first parent, while other parents
> may totally be able to provide a better combination.
>
> Clocks in that case cannot use divider_round_rate, so would have to come up
> with a very similar logic to work around it. Instead of having to do
> something like this, and duplicate that logic everywhere, create a
> divider_round_rate parent to allow caller to give an additional parameter
> for the parent clock to consider.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
> ---
>  drivers/clk/clk-divider.c    | 26 ++++++++++++++++++--------
>  include/linux/clk-provider.h |  4 ++++
>  2 files changed, 22 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index 96386ffc8483..48750439b1cd 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -275,7 +275,8 @@ static int _next_div(const struct clk_div_table *table, int div,
>         return div;
>  }
>
> -static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
> +static int clk_divider_bestdiv(struct clk_hw *hw, struct clk_hw *parent,
> +                              unsigned long rate,
>                                unsigned long *best_parent_rate,
>                                const struct clk_div_table *table, u8 width,
>                                unsigned long flags)
> @@ -314,8 +315,7 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
>                         *best_parent_rate = parent_rate_saved;
>                         return i;
>                 }
> -               parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
> -                                              rate * i);
> +               parent_rate = clk_hw_round_rate(parent, rate * i);
>                 now = DIV_ROUND_UP_ULL((u64)parent_rate, i);
>                 if (_is_best_div(rate, now, best, flags)) {
>                         bestdiv = i;
> @@ -326,22 +326,32 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
>
>         if (!bestdiv) {
>                 bestdiv = _get_maxdiv(table, width, flags);
> -               *best_parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), 1);
> +               *best_parent_rate = clk_hw_round_rate(parent, 1);
>         }
>
>         return bestdiv;
>  }
>
> -long divider_round_rate(struct clk_hw *hw, unsigned long rate,
> -                       unsigned long *prate, const struct clk_div_table *table,
> -                       u8 width, unsigned long flags)
> +long divider_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
> +                              unsigned long rate, unsigned long *prate,
> +                              const struct clk_div_table *table,
> +                              u8 width, unsigned long flags)
>  {
>         int div;
>
> -       div = clk_divider_bestdiv(hw, rate, prate, table, width, flags);
> +       div = clk_divider_bestdiv(hw, parent, rate, prate, table, width, flags);
>
>         return DIV_ROUND_UP_ULL((u64)*prate, div);
>  }
> +EXPORT_SYMBOL_GPL(divider_round_rate_parent);
> +
> +long divider_round_rate(struct clk_hw *hw, unsigned long rate,
> +                       unsigned long *prate, const struct clk_div_table *table,
> +                       u8 width, unsigned long flags)
> +{
> +       return divider_round_rate_parent(hw, clk_hw_get_parent(hw), rate, prate,
> +                                        table, width, flags);
> +}
>  EXPORT_SYMBOL_GPL(divider_round_rate);

Could this be made a static inline instead? Otherwise,

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

>
>  static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index a428aec36ace..14102f783f64 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -412,6 +412,10 @@ extern const struct clk_ops clk_divider_ro_ops;
>  unsigned long divider_recalc_rate(struct clk_hw *hw, unsigned long parent_rate,
>                 unsigned int val, const struct clk_div_table *table,
>                 unsigned long flags);
> +long divider_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
> +                              unsigned long rate, unsigned long *prate,
> +                              const struct clk_div_table *table,
> +                              u8 width, unsigned long flags);
>  long divider_round_rate(struct clk_hw *hw, unsigned long rate,
>                 unsigned long *prate, const struct clk_div_table *table,
>                 u8 width, unsigned long flags);
> --
> git-series 0.8.11

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