| Message ID | 20230702-pll-mipi_set_rate_parent-v3-1-46dcb8aa9cbc@oltmanns.dev (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | clk: sunxi-ng: Consider alternative parent rates when determining NKM clock rate | expand |
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
On 2023-07-03 at 08:47:43 +0200, Maxime Ripard <maxime@cerno.tech> wrote: > [[PGP Signed Part:Undecided]] > 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. I'll address that in v4. > > 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) Ok, will do in v4. > >> 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? Ugh. Yeah, sorry. I had that error in V2 but squashed the correction into patch 5 instead of patch 1. I'll fix that in v4. Thanks, Frank > > Maxime > > [[End of PGP Signed Part]]
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);
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(-)