Messages in this thread | | | Date | Mon, 3 Jul 2023 08:47:43 +0200 | From | Maxime Ripard <> | Subject | Re: [PATCH v3 1/8] clk: sunxi-ng: nkm: consider alternative parent rates when determining rate |
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Hi,
On Sun, Jul 02, 2023 at 07:55:20PM +0200, Frank Oltmanns wrote: > 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)
The usual order in that driver (and Linux in general) would make the clk_hw and nkm structure pointers first, and then the parent rate and rate.
But something looks off to me: ccu_nkm_find_best_with_parent_adj takes a pointer to the parent rate which makes sense since we're going to modify it.
> +{ > + 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)
You haven't modified ccu_nkm_find_best though, and it still takes the parent rate value.
> { > @@ -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,
(This should be another patch)
> 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);
parent_rate is a pointer, we were dereferencing it to pass its value to ccu_nkm_find_best. All good so far.
> + if (!clk_hw_can_set_rate_parent(&nkm->common.hw)) > + rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm);
Still passing by value
> + else > + rate = ccu_nkm_find_best_with_parent_adj(parent_rate, rate, &_nkm, parent_hw);
And passing the pointer there since it takes a pointer. Still good.
> > 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);
But here, we're passing a pointer to parent_rate to ccu_nkm_find_best, while it's still supposed to take it by value?
Maxime [unhandled content-type:application/pgp-signature] | |