On Sun, May 06, 2012 at 10:08:27PM -0700, Mike Turquette wrote:
> Patch 'clk: always pass parent_rate into .round_rate' made a subtle
> change to the semantics of .round_rate. It is now expected for the
> parent's rate to always be passed in, simplifying the implemenation of
> various .round_rate callback definitions.
>
> However the patch also introduced a bug in clk_calc_new_rates whereby a
> clock without the CLK_SET_RATE_PARENT flag set could still propagate a
> rate change up to a parent clock if the the .round_rate callback
> modified the &best_parent_rate value in any way.
>
> This patch fixes the issue at the framework level (in
> clk_calc_new_rates) by specifically handling the case where the
> CLK_SET_RATE_PARENT flag is not set.
>
> Signed-off-by: Mike Turquette <mturque...@linaro.org>
> Reported-by: Sascha Hauer<s.ha...@pengutronix.de>
I think a warning might be useful when a clk driver tries to change the
parent rate even if it is not allowed to. This can be added in a later
patch, so
Acked-by: Sascha Hauer <s.ha...@pengutronix.de>
Sascha
> ---
> drivers/clk/clk.c | 7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 8149764..7ceca0e 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -774,12 +774,18 @@ static struct clk *clk_calc_new_rates(struct clk *clk,
> unsigned long rate)
> if (IS_ERR_OR_NULL(clk))
> return NULL;
>
> + /* save parent rate, if it exists */
> + if (clk->parent)
> + best_parent_rate = clk->parent->rate;
> +
> /* never propagate up to the parent */
> if (!(clk->flags & CLK_SET_RATE_PARENT)) {
> if (!clk->ops->round_rate) {
> clk->new_rate = clk->rate;
> return NULL;
> }
> + new_rate = clk->ops->round_rate(clk->hw, rate,
> &best_parent_rate);
> + goto out;
> }
>
> /* need clk->parent from here on out */
> @@ -795,7 +801,6 @@ static struct clk *clk_calc_new_rates(struct clk *clk,
> unsigned long rate)
> goto out;
> }
>
> - best_parent_rate = clk->parent->rate;
> new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
>
> if (best_parent_rate != clk->parent->rate) {
> --
> 1.7.5.4
>
>
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