diff mbox

[v2,01/16] clk: sunxi-ng: Add check for minimal rate to NM PLLs

Message ID 20180227222701.9716-2-jernej.skrabec@siol.net (mailing list archive)
State New, archived
Headers show

Commit Message

Jernej Škrabec Feb. 27, 2018, 10:26 p.m. UTC
Some NM PLLs doesn't work well when their output clock rate is set below
certain rate.

Add support for that constrain.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
---
 drivers/clk/sunxi-ng/ccu_nm.c | 11 +++++++----
 drivers/clk/sunxi-ng/ccu_nm.h | 27 +++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

Comments

Maxime Ripard Feb. 28, 2018, 7:34 a.m. UTC | #1
Hi,

On Tue, Feb 27, 2018 at 11:26:46PM +0100, Jernej Skrabec wrote:
> Some NM PLLs doesn't work well when their output clock rate is set below
> certain rate.
> 
> Add support for that constrain.
> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> ---
>  drivers/clk/sunxi-ng/ccu_nm.c | 11 +++++++----
>  drivers/clk/sunxi-ng/ccu_nm.h | 27 +++++++++++++++++++++++++++
>  2 files changed, 34 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
> index a16de092bf94..7fc743c78c1b 100644
> --- a/drivers/clk/sunxi-ng/ccu_nm.c
> +++ b/drivers/clk/sunxi-ng/ccu_nm.c
> @@ -20,7 +20,7 @@ struct _ccu_nm {
>  };
>  
>  static void ccu_nm_find_best(unsigned long parent, unsigned long rate,
> -			     struct _ccu_nm *nm)
> +			     unsigned long min_rate, struct _ccu_nm *nm)
>  {
>  	unsigned long best_rate = 0;
>  	unsigned long best_n = 0, best_m = 0;
> @@ -30,7 +30,7 @@ static void ccu_nm_find_best(unsigned long parent, unsigned long rate,
>  		for (_m = nm->min_m; _m <= nm->max_m; _m++) {
>  			unsigned long tmp_rate = parent * _n  / _m;
>  
> -			if (tmp_rate > rate)
> +			if (tmp_rate > rate || tmp_rate < min_rate)
>  				continue;
>  
>  			if ((rate - tmp_rate) < (rate - best_rate)) {
> @@ -117,6 +117,9 @@ static long ccu_nm_round_rate(struct clk_hw *hw, unsigned long rate,
>  	if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
>  		rate *= nm->fixed_post_div;
>  
> +	if (rate < nm->min_rate)
> +		rate = nm->min_rate;
> +

I guess you can just return there. There's no point in trying to find
the factors at this point, since the minimum should be a value that
can be reached.

>  	if (ccu_frac_helper_has_rate(&nm->common, &nm->frac, rate)) {
>  		if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
>  			rate /= nm->fixed_post_div;
> @@ -134,7 +137,7 @@ static long ccu_nm_round_rate(struct clk_hw *hw, unsigned long rate,
>  	_nm.min_m = 1;
>  	_nm.max_m = nm->m.max ?: 1 << nm->m.width;
>  
> -	ccu_nm_find_best(*parent_rate, rate, &_nm);
> +	ccu_nm_find_best(*parent_rate, rate, nm->min_rate, &_nm);

Therefore, you don't need to change the prototype there either.

Maxime
Jernej Škrabec Feb. 28, 2018, 9:55 p.m. UTC | #2
Hi,

Dne sreda, 28. februar 2018 ob 08:34:40 CET je Maxime Ripard napisal(a):
> Hi,
> 
> On Tue, Feb 27, 2018 at 11:26:46PM +0100, Jernej Skrabec wrote:
> > Some NM PLLs doesn't work well when their output clock rate is set below
> > certain rate.
> > 
> > Add support for that constrain.
> > 
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > ---
> > 
> >  drivers/clk/sunxi-ng/ccu_nm.c | 11 +++++++----
> >  drivers/clk/sunxi-ng/ccu_nm.h | 27 +++++++++++++++++++++++++++
> >  2 files changed, 34 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
> > index a16de092bf94..7fc743c78c1b 100644
> > --- a/drivers/clk/sunxi-ng/ccu_nm.c
> > +++ b/drivers/clk/sunxi-ng/ccu_nm.c
> > @@ -20,7 +20,7 @@ struct _ccu_nm {
> > 
> >  };
> >  
> >  static void ccu_nm_find_best(unsigned long parent, unsigned long rate,
> > 
> > -			     struct _ccu_nm *nm)
> > +			     unsigned long min_rate, struct _ccu_nm *nm)
> > 
> >  {
> >  
> >  	unsigned long best_rate = 0;
> >  	unsigned long best_n = 0, best_m = 0;
> > 
> > @@ -30,7 +30,7 @@ static void ccu_nm_find_best(unsigned long parent,
> > unsigned long rate,> 
> >  		for (_m = nm->min_m; _m <= nm->max_m; _m++) {
> >  		
> >  			unsigned long tmp_rate = parent * _n  / _m;
> > 
> > -			if (tmp_rate > rate)
> > +			if (tmp_rate > rate || tmp_rate < min_rate)
> > 
> >  				continue;
> >  			
> >  			if ((rate - tmp_rate) < (rate - best_rate)) {
> > 
> > @@ -117,6 +117,9 @@ static long ccu_nm_round_rate(struct clk_hw *hw,
> > unsigned long rate,> 
> >  	if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
> >  	
> >  		rate *= nm->fixed_post_div;
> > 
> > +	if (rate < nm->min_rate)
> > +		rate = nm->min_rate;
> > +
> 
> I guess you can just return there. There's no point in trying to find
> the factors at this point, since the minimum should be a value that
> can be reached.
> 

Right, I already tested it and it works.

Best regards,
Jernej

> >  	if (ccu_frac_helper_has_rate(&nm->common, &nm->frac, rate)) {
> >  	
> >  		if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
> >  		
> >  			rate /= nm->fixed_post_div;
> > 
> > @@ -134,7 +137,7 @@ static long ccu_nm_round_rate(struct clk_hw *hw,
> > unsigned long rate,> 
> >  	_nm.min_m = 1;
> >  	_nm.max_m = nm->m.max ?: 1 << nm->m.width;
> > 
> > -	ccu_nm_find_best(*parent_rate, rate, &_nm);
> > +	ccu_nm_find_best(*parent_rate, rate, nm->min_rate, &_nm);
> 
> Therefore, you don't need to change the prototype there either.
> 
> Maxime
> 
> --
> Maxime Ripard, Bootlin (formerly Free Electrons)
> Embedded Linux and Kernel engineering
> https://bootlin.com
diff mbox

Patch

diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
index a16de092bf94..7fc743c78c1b 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.c
+++ b/drivers/clk/sunxi-ng/ccu_nm.c
@@ -20,7 +20,7 @@  struct _ccu_nm {
 };
 
 static void ccu_nm_find_best(unsigned long parent, unsigned long rate,
-			     struct _ccu_nm *nm)
+			     unsigned long min_rate, struct _ccu_nm *nm)
 {
 	unsigned long best_rate = 0;
 	unsigned long best_n = 0, best_m = 0;
@@ -30,7 +30,7 @@  static void ccu_nm_find_best(unsigned long parent, unsigned long rate,
 		for (_m = nm->min_m; _m <= nm->max_m; _m++) {
 			unsigned long tmp_rate = parent * _n  / _m;
 
-			if (tmp_rate > rate)
+			if (tmp_rate > rate || tmp_rate < min_rate)
 				continue;
 
 			if ((rate - tmp_rate) < (rate - best_rate)) {
@@ -117,6 +117,9 @@  static long ccu_nm_round_rate(struct clk_hw *hw, unsigned long rate,
 	if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
 		rate *= nm->fixed_post_div;
 
+	if (rate < nm->min_rate)
+		rate = nm->min_rate;
+
 	if (ccu_frac_helper_has_rate(&nm->common, &nm->frac, rate)) {
 		if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
 			rate /= nm->fixed_post_div;
@@ -134,7 +137,7 @@  static long ccu_nm_round_rate(struct clk_hw *hw, unsigned long rate,
 	_nm.min_m = 1;
 	_nm.max_m = nm->m.max ?: 1 << nm->m.width;
 
-	ccu_nm_find_best(*parent_rate, rate, &_nm);
+	ccu_nm_find_best(*parent_rate, rate, nm->min_rate, &_nm);
 	rate = *parent_rate * _nm.n / _nm.m;
 
 	if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
@@ -186,7 +189,7 @@  static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long rate,
 					   &_nm.m, &_nm.n);
 	} else {
 		ccu_sdm_helper_disable(&nm->common, &nm->sdm);
-		ccu_nm_find_best(parent_rate, rate, &_nm);
+		ccu_nm_find_best(parent_rate, rate, nm->min_rate, &_nm);
 	}
 
 	spin_lock_irqsave(nm->common.lock, flags);
diff --git a/drivers/clk/sunxi-ng/ccu_nm.h b/drivers/clk/sunxi-ng/ccu_nm.h
index eba586b4c7d0..1d8b459c50b7 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.h
+++ b/drivers/clk/sunxi-ng/ccu_nm.h
@@ -37,6 +37,7 @@  struct ccu_nm {
 	struct ccu_sdm_internal		sdm;
 
 	unsigned int		fixed_post_div;
+	unsigned int		min_rate;
 
 	struct ccu_common	common;
 };
@@ -88,6 +89,32 @@  struct ccu_nm {
 		},							\
 	}
 
+#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN(_struct, _name, _parent,	\
+					     _reg, _min_rate,		\
+					     _nshift, _nwidth,		\
+					     _mshift, _mwidth,		\
+					     _frac_en, _frac_sel,	\
+					     _frac_rate_0, _frac_rate_1,\
+					     _gate, _lock, _flags)	\
+	struct ccu_nm _struct = {					\
+		.enable		= _gate,				\
+		.lock		= _lock,				\
+		.n		= _SUNXI_CCU_MULT(_nshift, _nwidth),	\
+		.m		= _SUNXI_CCU_DIV(_mshift, _mwidth),	\
+		.frac		= _SUNXI_CCU_FRAC(_frac_en, _frac_sel,	\
+						  _frac_rate_0,		\
+						  _frac_rate_1),	\
+		.min_rate	= _min_rate,				\
+		.common		= {					\
+			.reg		= _reg,				\
+			.features	= CCU_FEATURE_FRACTIONAL,	\
+			.hw.init	= CLK_HW_INIT(_name,		\
+						      _parent,		\
+						      &ccu_nm_ops,	\
+						      _flags),		\
+		},							\
+	}
+
 #define SUNXI_CCU_NM_WITH_GATE_LOCK(_struct, _name, _parent, _reg,	\
 				    _nshift, _nwidth,			\
 				    _mshift, _mwidth,			\