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Subject: Re: [PATCH RESEND v7 4/4] clk: meson: add one based divider support
 for sclk divider
To:     Jerome Brunet <jbrunet@baylibre.com>,
        Neil Armstrong <narmstrong@baylibre.com>
CC:     Kevin Hilman <khilman@baylibre.com>,
        Carlo Caione <carlo@caione.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>, Rob Herring <robh@kernel.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Boris Brezillon <boris.brezillon@bootlin.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Yixun Lan <yixun.lan@amlogic.com>,
        Liang Yang <liang.yang@amlogic.com>,
        Jian Hu <jian.hu@amlogic.com>,
        Qiufang Dai <qiufang.dai@amlogic.com>,
        Hanjie Lin <hanjie.lin@amlogic.com>,
        Victor Wan <victor.wan@amlogic.com>,
        <linux-clk@vger.kernel.org>, <linux-amlogic@lists.infradead.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
References: <1544457877-51301-1-git-send-email-jianxin.pan@amlogic.com>
 <1544457877-51301-5-git-send-email-jianxin.pan@amlogic.com>
 <4da764c237b8f752af1dc33a011e2a4b73068f02.camel@baylibre.com>
From:   Jianxin Pan <jianxin.pan@amlogic.com>
Message-ID: <d748a030-441f-dab0-83f7-aa8fc1106cb4@amlogic.com>
Date:   Thu, 13 Dec 2018 16:03:39 +0800
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Hi Jerome,

Thanks for the fully review, we really appreciate your time.

On 2018/12/12 1:16, Jerome Brunet wrote:
> On Tue, 2018-12-11 at 00:04 +0800, Jianxin Pan wrote:
>> When CLK_DIVIDER_ONE_BASED flag is set, the sclk divider will be:
>> one based divider (div = val), and zero value gates the clock
>>
>> Signed-off-by: Jianxin Pan <jianxin.pan@amlogic.com>
>> ---
>>  drivers/clk/meson/clkc-audio.h |  1 +
>>  drivers/clk/meson/sclk-div.c   | 28 ++++++++++++++++++----------
>>  2 files changed, 19 insertions(+), 10 deletions(-)
> 
> Such a patch should be done earlier in the series, at least before using sclk
> in your controller, otherwise thing will be broken in between
> 
I will move it to the first one of the patchset. 
> In general, I would prefer if you had added two helper function to deal with
> the translation between register value and divider value.
> 
> Only these function should care about CLK_DIVIDER_ONE_BASED, the rest should
> just call them.
> 
> This, we will be able to deal the with HI (duty cycle) part as well, which you
> completly skiped.
> 
> I know your device does not have this, but still the code has to make sense.
> 
OK, I will add two helper for value and register translation, and then appy them to both div and hi.
>>
>> diff --git a/drivers/clk/meson/clkc-audio.h b/drivers/clk/meson/clkc-audio.h
>> index 0a7c157..9bd6ced 100644
>> --- a/drivers/clk/meson/clkc-audio.h
>> +++ b/drivers/clk/meson/clkc-audio.h
>> @@ -20,6 +20,7 @@ struct meson_sclk_div_data {
>>  	struct parm hi;
>>  	unsigned int cached_div;
>>  	struct clk_duty cached_duty;
>> +	u8	flags;
>>  };
>>  
>>  extern const struct clk_ops meson_clk_triphase_ops;
>> diff --git a/drivers/clk/meson/sclk-div.c b/drivers/clk/meson/sclk-div.c
>> index bc64019..d98707b 100644
>> --- a/drivers/clk/meson/sclk-div.c
>> +++ b/drivers/clk/meson/sclk-div.c
>> @@ -24,22 +24,23 @@
>>  	return (struct meson_sclk_div_data *)clk->data;
>>  }
>>  
>> -static int sclk_div_maxval(struct meson_sclk_div_data *sclk)
>> -{
>> -	return (1 << sclk->div.width) - 1;
>> -}
>> -
>>  static int sclk_div_maxdiv(struct meson_sclk_div_data *sclk)
>>  {
>> -	return sclk_div_maxval(sclk) + 1;
>> +	if (sclk->flags & CLK_DIVIDER_ONE_BASED)
>> +		return clk_div_mask(sclk->div.width);
>> +	else
>> +		return clk_div_mask(sclk->div.width) + 1;
> 
> seems over complicated.
> why no call clk_div_mask just once, and add 1 if necessary ?
Yes, I will use helper here.
> 
>>  }
>>  
>>  static int sclk_div_getdiv(struct clk_hw *hw, unsigned long rate,
>>  			   unsigned long prate, int maxdiv)
>>  {
>>  	int div = DIV_ROUND_CLOSEST_ULL((u64)prate, rate);
>> +	struct clk_regmap *clk = to_clk_regmap(hw);
>> +	struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
>> +	int mindiv = (sclk->flags & CLK_DIVIDER_ONE_BASED) ? 1 : 2;
> 
> This is why I want helpers, don't like this above
OK, I will replace it with helpers.
> 
>>  
>> -	return clamp(div, 2, maxdiv);
>> +	return clamp(div, mindiv, maxdiv);
>>  }
>>  
>>  static int sclk_div_bestdiv(struct clk_hw *hw, unsigned long rate,
>> @@ -47,7 +48,7 @@ static int sclk_div_bestdiv(struct clk_hw *hw, unsigned
>> long rate,
>>  			    struct meson_sclk_div_data *sclk)
>>  {
>>  	struct clk_hw *parent = clk_hw_get_parent(hw);
>> -	int bestdiv = 0, i;
>> +	int bestdiv = 0, i, mindiv;
>>  	unsigned long maxdiv, now, parent_now;
>>  	unsigned long best = 0, best_parent = 0;
>>  
>> @@ -64,8 +65,9 @@ static int sclk_div_bestdiv(struct clk_hw *hw, unsigned
>> long rate,
>>  	 * unsigned long in rate * i below
>>  	 */
>>  	maxdiv = min(ULONG_MAX / rate, maxdiv);
>> +	mindiv = (sclk->flags & CLK_DIVIDER_ONE_BASED) ? 1 : 2;
>>  
>> -	for (i = 2; i <= maxdiv; i++) {
>> +	for (i = mindiv; i <= maxdiv; i++) {
>>  		/*
>>  		 * It's the most ideal case if the requested rate can be
>>  		 * divided from parent clock without needing to change
>> @@ -153,10 +155,14 @@ static int sclk_div_get_duty_cycle(struct clk_hw *hw,
>>  static void sclk_apply_divider(struct clk_regmap *clk,
>>  			       struct meson_sclk_div_data *sclk)
>>  {
>> +	unsigned int div;
>> +
>>  	if (MESON_PARM_APPLICABLE(&sclk->hi))
>>  		sclk_apply_ratio(clk, sclk);
>>  
>> -	meson_parm_write(clk->map, &sclk->div, sclk->cached_div - 1);
>> +	div = (sclk->flags & CLK_DIVIDER_ONE_BASED) ?
>> +		sclk->cached_div : (sclk->cached_div - 1);
> 
> helpers again.
OK!
> 
>> +	meson_parm_write(clk->map, &sclk->div, div);
>>  }
>>  
>>  static int sclk_div_set_rate(struct clk_hw *hw, unsigned long rate,
>> @@ -223,6 +229,8 @@ static void sclk_div_init(struct clk_hw *hw)
>>  	/* if the divider is initially disabled, assume max */
>>  	if (!val)
>>  		sclk->cached_div = sclk_div_maxdiv(sclk);
>> +	else if (sclk->flags & CLK_DIVIDER_ONE_BASED)
>> +		sclk->cached_div = val;
>>  	else
>>  		sclk->cached_div = val + 1;
> 
> same ...
OK, I will fix them. Thanks again for your time!
> 
>>  
> 
> 
> .
>