Messages in this thread Patch in this message | | | From | Frank Oltmanns <> | Date | Sun, 02 Jul 2023 19:55:20 +0200 | Subject | [PATCH v3 1/8] clk: sunxi-ng: nkm: consider alternative parent rates when determining rate |
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In case the CLK_SET_RATE_PARENT flag is set, consider using a different parent rate when determining a new rate.
To find the best match for the requested rate, perform the following steps for each NKM combination: - calculate the optimal parent rate, - find the best parent rate that the parent clock actually supports - use that parent rate to calculate the effective rate.
In case the clk does not support setting the parent rate, use the same algorithm as before.
Signed-off-by: Frank Oltmanns <frank@oltmanns.dev> --- drivers/clk/sunxi-ng/ccu_nkm.c | 48 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 45 insertions(+), 3 deletions(-)
diff --git a/drivers/clk/sunxi-ng/ccu_nkm.c b/drivers/clk/sunxi-ng/ccu_nkm.c index a0978a50edae..d83843e69c25 100644 --- a/drivers/clk/sunxi-ng/ccu_nkm.c +++ b/drivers/clk/sunxi-ng/ccu_nkm.c @@ -6,6 +6,7 @@ #include <linux/clk-provider.h> #include <linux/io.h> +#include <linux/math.h> #include "ccu_gate.h" #include "ccu_nkm.h" @@ -16,6 +17,44 @@ struct _ccu_nkm { unsigned long m, min_m, max_m; }; +static unsigned long ccu_nkm_find_best_with_parent_adj(unsigned long *parent, unsigned long rate, + struct _ccu_nkm *nkm, struct clk_hw *phw) +{ + unsigned long best_rate = 0, best_parent_rate = *parent, tmp_parent = *parent; + unsigned long best_n = 0, best_k = 0, best_m = 0; + unsigned long _n, _k, _m; + + for (_k = nkm->min_k; _k <= nkm->max_k; _k++) { + for (_n = nkm->min_n; _n <= nkm->max_n; _n++) { + for (_m = nkm->min_m; _m <= nkm->max_m; _m++) { + unsigned long tmp_rate; + + tmp_parent = clk_hw_round_rate(phw, rate * _m / (_n * _k)); + + tmp_rate = tmp_parent * _n * _k / _m; + if (tmp_rate > rate) + continue; + + if ((rate - tmp_rate) < (rate - best_rate)) { + best_rate = tmp_rate; + best_parent_rate = tmp_parent; + best_n = _n; + best_k = _k; + best_m = _m; + } + } + } + } + + nkm->n = best_n; + nkm->k = best_k; + nkm->m = best_m; + + *parent = best_parent_rate; + + return best_rate; +} + static unsigned long ccu_nkm_find_best(unsigned long parent, unsigned long rate, struct _ccu_nkm *nkm) { @@ -106,7 +145,7 @@ static unsigned long ccu_nkm_recalc_rate(struct clk_hw *hw, } static unsigned long ccu_nkm_round_rate(struct ccu_mux_internal *mux, - struct clk_hw *hw, + struct clk_hw *parent_hw, unsigned long *parent_rate, unsigned long rate, void *data) @@ -124,7 +163,10 @@ static unsigned long ccu_nkm_round_rate(struct ccu_mux_internal *mux, if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV) rate *= nkm->fixed_post_div; - rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm); + if (!clk_hw_can_set_rate_parent(&nkm->common.hw)) + rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm); + else + rate = ccu_nkm_find_best_with_parent_adj(parent_rate, rate, &_nkm, parent_hw); if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV) rate /= nkm->fixed_post_div; @@ -159,7 +201,7 @@ static int ccu_nkm_set_rate(struct clk_hw *hw, unsigned long rate, _nkm.min_m = 1; _nkm.max_m = nkm->m.max ?: 1 << nkm->m.width; - ccu_nkm_find_best(parent_rate, rate, &_nkm); + ccu_nkm_find_best(&parent_rate, rate, &_nkm); spin_lock_irqsave(nkm->common.lock, flags); -- 2.41.0
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