Re: [PATCH 1/15] clk: divider: Make divider_round_rate take the parent clock

Stephen Boyd
2017-03-07T14:11:57Z

On 03/07, Maxime Ripard 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, give an
> additional parameter for the parent clock to consider.
>
> Current users have been converted using the following coccinelle script
>
> @@
> identifier hw, rate, prate, table, width, flags;
> @@
>
> -long divider_round_rate(struct clk_hw *hw,
> +long divider_round_rate(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) { ... }
>
> @@
> identifier fn, hw;
> expression E2, E3, E4, E5, E6;
> @@
> fn (struct clk_hw *hw, ...) {
> <...
> -divider_round_rate(hw, E2, E3, E4, E5, E6)
> +divider_round_rate(hw, clk_hw_get_parent(hw), E2, E3, E4, E5, E6)
> ...>
> }

Why not introduce another function like

divider_round_rate_parent()
divider_round_rate_mux()

that takes the extra parent argument? Technically, a divider is
considered to only have one parent, and if it has more than one
parent, then it is a mux and a divider.

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