linux-kernel - Re: [PATCH 3/5] clk: sunxi-ng: nm: Support constraints on n/m ratio and parent rate

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Date: Tue, 19 Dec 2023 17:52:40 +0100
From: Jernej Škrabec <jernej.skrabec@...il.com>
To: Michael Turquette <mturquette@...libre.com>,
 Stephen Boyd <sboyd@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
 Samuel Holland <samuel@...lland.org>,
 Guido Günther <agx@...xcpu.org>,
 Purism Kernel Team <kernel@...i.sm>, Ondrej Jirman <megi@....cz>,
 Neil Armstrong <neil.armstrong@...aro.org>,
 Jessica Zhang <quic_jesszhan@...cinc.com>, Sam Ravnborg <sam@...nborg.org>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Frank Oltmanns <frank@...manns.dev>
Cc: linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, Frank Oltmanns <frank@...manns.dev>
Subject:
 Re: [PATCH 3/5] clk: sunxi-ng: nm: Support constraints on n/m ratio and
 parent rate

Dne ponedeljek, 18. december 2023 ob 14:35:21 CET je Frank Oltmanns napisal(a):
> The Allwinner A64 manual lists the following constraint for the
> PLL-VIDEO0 clock: 8 <= N/M <= 25
> 
> The PLL-MIPI clock is implemented as ccu_nm. Therefore, add support for
> this constraint.
> 
> Signed-off-by: Frank Oltmanns <frank@...manns.dev>
> ---
>  drivers/clk/sunxi-ng/ccu_nm.c | 21 +++++++++++++++++++--
>  drivers/clk/sunxi-ng/ccu_nm.h | 34 ++++++++++++++++++++++++++++++++--
>  2 files changed, 51 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
> index ffac3deb89d6..cfc6981e398b 100644
> --- a/drivers/clk/sunxi-ng/ccu_nm.c
> +++ b/drivers/clk/sunxi-ng/ccu_nm.c
> @@ -27,6 +27,19 @@ static unsigned long ccu_nm_calc_rate(unsigned long parent,
>  	return rate;
>  }
>  
> +static bool ccu_nm_is_valid_rate(struct ccu_common *common, unsigned long n, unsigned long m)
> +{
> +	struct ccu_nm *nm = container_of(common, struct ccu_nm, common);
> +
> +	if (nm->max_nm_ratio && (n > nm->max_nm_ratio * m))
> +		return false;
> +
> +	if (nm->min_nm_ratio && (n < nm->min_nm_ratio * m))
> +		return false;
> +
> +	return true;
> +}
> +
>  static unsigned long ccu_nm_find_best(struct ccu_common *common, unsigned long parent,
>  				      unsigned long rate, struct _ccu_nm *nm)
>  {
> @@ -36,8 +49,12 @@ static unsigned long ccu_nm_find_best(struct ccu_common *common, unsigned long p
>  
>  	for (_n = nm->min_n; _n <= nm->max_n; _n++) {
>  		for (_m = nm->min_m; _m <= nm->max_m; _m++) {
> -			unsigned long tmp_rate = ccu_nm_calc_rate(parent,
> -								  _n, _m);
> +			unsigned long tmp_rate;
> +
> +			if (!ccu_nm_is_valid_rate(common, _n, _m))
> +				continue;
> +
> +			tmp_rate = ccu_nm_calc_rate(parent, _n, _m);
>  
>  			if (ccu_is_better_rate(common, rate, tmp_rate, best_rate)) {
>  				best_rate = tmp_rate;
> diff --git a/drivers/clk/sunxi-ng/ccu_nm.h b/drivers/clk/sunxi-ng/ccu_nm.h
> index 93c11693574f..0075df6d9697 100644
> --- a/drivers/clk/sunxi-ng/ccu_nm.h
> +++ b/drivers/clk/sunxi-ng/ccu_nm.h
> @@ -31,6 +31,8 @@ struct ccu_nm {
>  	unsigned int		fixed_post_div;
>  	unsigned int		min_rate;
>  	unsigned int		max_rate;
> +	unsigned long		min_nm_ratio; /* minimum value for m/n */
> +	unsigned long		max_nm_ratio; /* maximum value for m/n */

Comment is wrong, it should be "n/m". For consistency with nkm patch,
min_n_m_ratio and max_n_m_ratio.

Best regards,
Jernej

>  
>  	struct ccu_common	common;
>  };
> @@ -108,7 +110,8 @@ struct ccu_nm {
>  		},							\
>  	}
>  
> -#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT(_struct, _name,	\
> +#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT_NM_RATIO(		\
> +						 _struct, _name,	\
>  						 _parent, _reg,		\
>  						 _min_rate, _max_rate,	\
>  						 _nshift, _nwidth,	\
> @@ -117,7 +120,9 @@ struct ccu_nm {
>  						 _frac_rate_0,		\
>  						 _frac_rate_1,		\
>  						 _gate, _lock, _flags,	\
> -						 _features)		\
> +						 _features,		\
> +						 _min_nm_ratio,		\
> +						 _max_nm_ratio)		\
>  	struct ccu_nm _struct = {					\
>  		.enable		= _gate,				\
>  		.lock		= _lock,				\
> @@ -128,6 +133,8 @@ struct ccu_nm {
>  						  _frac_rate_1),	\
>  		.min_rate	= _min_rate,				\
>  		.max_rate	= _max_rate,				\
> +		.min_nm_ratio	= _min_nm_ratio,			\
> +		.max_nm_ratio	= _max_nm_ratio,			\
>  		.common		= {					\
>  			.reg		= _reg,				\
>  			.features	= _features,			\
> @@ -138,6 +145,29 @@ struct ccu_nm {
>  		},							\
>  	}
>  
> +#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT(_struct, _name,	\
> +						 _parent, _reg,		\
> +						 _min_rate, _max_rate,	\
> +						 _nshift, _nwidth,	\
> +						 _mshift, _mwidth,	\
> +						 _frac_en, _frac_sel,	\
> +						 _frac_rate_0,		\
> +						 _frac_rate_1,		\
> +						 _gate, _lock, _flags,	\
> +						 _features)		\
> +	SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX_FEAT_NM_RATIO(		\
> +						_struct, _name,		\
> +						_parent, _reg,		\
> +						_min_rate, _max_rate,	\
> +						_nshift, _nwidth,	\
> +						_mshift, _mwidth,	\
> +						_frac_en, _frac_sel,	\
> +						_frac_rate_0,		\
> +						_frac_rate_1,		\
> +						_gate, _lock, _flags,	\
> +						_features,		\
> +						0, 0)
> +
>  #define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN_MAX(_struct, _name,	\
>  						 _parent, _reg,		\
>  						 _min_rate, _max_rate,	\
> 
>