Quoting Alex Elder (2014-05-20 06:24:57)
> Implement the clk->determine_rate method for Broadcom Kona peripheral
> clocks. This allows a peripheral clock to be re-parented in order to
> satisfy a rate change request. This takes the place of the previous
> kona_peri_clk_round_rate() functionality, though that function remains
> because it is used by the new one.
>
> The parent clock that allows the peripheral clock to produce a rate
> closest to the one requested is the one selected, though the current
> parent is used by default.
>
> Signed-off-by: Alex Elder <el...@linaro.org>
> ---
> This patch is based on Mike Turquette's current "clk-next" branch.
> 6ed8eb5 Merge tag 'clk-hisi-for-v3.16' of https://git.kern...
>
> It is available here:
> http://git.linaro.org/landing-teams/working/broadcom/kernel.git
> Branch review/bcm-determine-rate
>
> drivers/clk/bcm/clk-kona.c | 53
> +++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 52 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
> index d603c4e..1a4eccc 100644
> --- a/drivers/clk/bcm/clk-kona.c
> +++ b/drivers/clk/bcm/clk-kona.c
> @@ -1031,6 +1031,57 @@ static long kona_peri_clk_round_rate(struct clk_hw
> *hw, unsigned long rate,
> rate ? rate : 1, *parent_rate, NULL);
> }
>
> +static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long
> rate,
> + unsigned long *best_parent_rate, struct clk **best_parent)
> +{
> + struct kona_clk *bcm_clk = to_kona_clk(hw);
> + struct clk *clk = hw->clk;
> + struct clk *current_parent;
> + unsigned long parent_rate;
> + unsigned long best_delta;
> + unsigned long best_rate;
> + u32 parent_count;
> + u32 which;
> +
> + /*
> + * If there is no other parent to choose, use the current one.
> + * Note: We don't honor (or use) CLK_SET_RATE_NO_REPARENT.
> + */
A WARN_ONCE is appropriate upon detection of CLK_SET_RATE_NO_REPARENT.
It will certainly help someone that is debugging why that flag has no
effect.
Otherwise the patch looks good to me.
Regards,
Mike
> + parent_count = (u32)bcm_clk->init_data.num_parents;
> + if (parent_count < 2)
> + return kona_peri_clk_round_rate(hw, rate, best_parent_rate);
> +
> + /* Unless we can do better, stick with current parent */
> + current_parent = clk_get_parent(clk);
> + parent_rate = __clk_get_rate(current_parent);
> + best_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate);
> + best_delta = abs(best_rate - rate);
> +
> + /* Check whether any other parent clock can produce a better result */
> + for (which = 0; which < parent_count; which++) {
> + struct clk *parent = clk_get_parent_by_index(clk, which);
> + unsigned long delta;
> + unsigned long other_rate;
> +
> + BUG_ON(!parent);
> + if (parent == current_parent)
> + continue;
> +
> + /* We don't support CLK_SET_RATE_PARENT */
> + parent_rate = __clk_get_rate(parent);
> + other_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate);
> + delta = abs(other_rate - rate);
> + if (delta < best_delta) {
> + best_delta = delta;
> + best_rate = other_rate;
> + *best_parent = parent;
> + *best_parent_rate = parent_rate;
> + }
> + }
> +
> + return best_rate;
> +}
> +
> static int kona_peri_clk_set_parent(struct clk_hw *hw, u8 index)
> {
> struct kona_clk *bcm_clk = to_kona_clk(hw);
> @@ -1135,7 +1186,7 @@ struct clk_ops kona_peri_clk_ops = {
> .disable = kona_peri_clk_disable,
> .is_enabled = kona_peri_clk_is_enabled,
> .recalc_rate = kona_peri_clk_recalc_rate,
> - .round_rate = kona_peri_clk_round_rate,
> + .determine_rate = kona_peri_clk_determine_rate,
> .set_parent = kona_peri_clk_set_parent,
> .get_parent = kona_peri_clk_get_parent,
> .set_rate = kona_peri_clk_set_rate,
> --
> 1.9.1
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
