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SubjectRe: [PATCH 2/6] clk: fix clk_calc_subtree compute duplications
On Tue, Oct 23, 2018 at 6:31 PM Derek Basehore <dbasehore@chromium.org> wrote:
>
> clk_calc_subtree was called at every step up the clk tree in
> clk_calc_new_rates. Since it recursively calls itself for its
> children, this means it would be called once on each clk for each
> step above the top clk is.
>
> This fixes this by breaking the subtree calculation into two parts.
> The first part recalcs the rate for each child of the parent clk in
> clk_calc_new_rates. This part is not recursive itself. The second part
> recursively calls a new clk_calc_subtree on the clk_core that was
> passed into clk_set_rate.
>
> Signed-off-by: Derek Basehore <dbasehore@chromium.org>
> ---
> drivers/clk/clk.c | 30 ++++++++++++++++++++----------
> 1 file changed, 20 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 95d818f5edb2..61de8ad3e4cf 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1717,11 +1717,19 @@ static int __clk_speculate_rates(struct clk_core *core,
> return ret;
> }
>
> -static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
> - struct clk_core *new_parent, u8 p_index)
> +static void clk_calc_subtree(struct clk_core *core)
> {
> struct clk_core *child;
>
> + hlist_for_each_entry(child, &core->children, child_node) {
> + child->new_rate = clk_recalc(child, core->new_rate);
> + clk_calc_subtree(child);
> + }
> +}
> +
> +static void clk_set_change(struct clk_core *core, unsigned long new_rate,
> + struct clk_core *new_parent, u8 p_index)
> +{
> core->new_rate = new_rate;
> core->new_parent = new_parent;
> core->new_parent_index = p_index;
> @@ -1729,11 +1737,6 @@ static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
> core->new_child = NULL;
> if (new_parent && new_parent != core->parent)
> new_parent->new_child = core;
> -
> - hlist_for_each_entry(child, &core->children, child_node) {
> - child->new_rate = clk_recalc(child, new_rate);
> - clk_calc_subtree(child, child->new_rate, NULL, 0);
> - }
> }
>
> /*
> @@ -1744,7 +1747,7 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *core,
> unsigned long rate)
> {
> struct clk_core *top = core;
> - struct clk_core *old_parent, *parent;
> + struct clk_core *old_parent, *parent, *child;
> unsigned long best_parent_rate = 0;
> unsigned long new_rate;
> unsigned long min_rate;
> @@ -1791,6 +1794,8 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *core,
> /* pass-through clock with adjustable parent */
> top = clk_calc_new_rates(parent, rate);
> new_rate = parent->new_rate;
> + hlist_for_each_entry(child, &parent->children, child_node)
> + child->new_rate = clk_recalc(child, new_rate);
> goto out;
> }
>
> @@ -1813,11 +1818,14 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *core,
> }
>
> if ((core->flags & CLK_SET_RATE_PARENT) && parent &&
> - best_parent_rate != parent->rate)
> + best_parent_rate != parent->rate) {
> top = clk_calc_new_rates(parent, best_parent_rate);
> + hlist_for_each_entry(child, &parent->children, child_node)
> + child->new_rate = clk_recalc(child, parent->new_rate);
> + }
>
> out:
> - clk_calc_subtree(core, new_rate, parent, p_index);
> + clk_set_change(core, new_rate, parent, p_index);
>
> return top;
> }
> @@ -2018,6 +2026,8 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
> if (ret)
> return ret;
>
> + clk_calc_subtree(core);

This should be:
hlist_for_each_entry(child, core->new_parent? core->new_parent :
core->parent, child_node)
clk_calc_subtree(child);

> +
> /* notify that we are about to change rates */
> fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
> if (fail_clk) {
> --
> 2.19.1.568.g152ad8e336-goog
>

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