On 25/07/2017 at 09:37, Quentin Schulz wrote:
> The driver requests the current clk rate of each of its parent clocks to
> decide whether a clock rate is suitable or not. It does not request
> determine_rate from a parent clock which could request a rate change in
> parent clock (i.e. there is no parent rate propagation).
>
> We know the rate we want (passed along req argument of the function) and
> the parent clock rate, thus we know the closest rounded divisor, we
> don't need to iterate over the available divisors to find the best one
> for a given clock.
>
> Signed-off-by: Quentin Schulz <quentin.sch...@free-electrons.com>
> Acked-by: Boris Brezillon <boris.brezil...@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.fe...@microchip.com>
> ---
> drivers/clk/at91/clk-generated.c | 25 ++++++++++++-------------
> 1 file changed, 12 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/clk/at91/clk-generated.c
> b/drivers/clk/at91/clk-generated.c
> index f0b7ae9..ef4b4e0 100644
> --- a/drivers/clk/at91/clk-generated.c
> +++ b/drivers/clk/at91/clk-generated.c
> @@ -124,19 +124,18 @@ static int clk_generated_determine_rate(struct clk_hw
> *hw,
> (gck->range.max && min_rate > gck->range.max))
> continue;
>
> - for (div = 1; div < GENERATED_MAX_DIV + 2; div++) {
> - tmp_rate = DIV_ROUND_CLOSEST(parent_rate, div);
> - tmp_diff = abs(req->rate - tmp_rate);
> -
> - if (best_diff < 0 || best_diff > tmp_diff) {
> - best_rate = tmp_rate;
> - best_diff = tmp_diff;
> - req->best_parent_rate = parent_rate;
> - req->best_parent_hw = parent;
> - }
> -
> - if (!best_diff || tmp_rate < req->rate)
> - break;
> + div = DIV_ROUND_CLOSEST(parent_rate, req->rate);
> + if (!div)
> + tmp_rate = parent_rate;
> + else
> + tmp_rate = parent_rate / div;
> + tmp_diff = abs(req->rate - tmp_rate);
> +
> + if (best_diff < 0 || best_diff > tmp_diff) {
> + best_rate = tmp_rate;
> + best_diff = tmp_diff;
> + req->best_parent_rate = parent_rate;
> + req->best_parent_hw = parent;
> }
>
> if (!best_diff)
>
--
Nicolas Ferre
