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Subject: Re: [PATCH v4 2/6] clk: meson: add support for A1 PLL clock ops
From:   Jian Hu <jian.hu@amlogic.com>
To:     Jerome Brunet <jbrunet@baylibre.com>,
        Neil Armstrong <narmstrong@baylibre.com>
CC:     Kevin Hilman <khilman@baylibre.com>, Rob Herring <robh@kernel.org>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Qiufang Dai <qiufang.dai@amlogic.com>,
        Jianxin Pan <jianxin.pan@amlogic.com>,
        Victor Wan <victor.wan@amlogic.com>,
        Chandle Zou <chandle.zou@amlogic.com>,
        <linux-clk@vger.kernel.org>, <linux-amlogic@lists.infradead.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>
References: <20191206074052.15557-1-jian.hu@amlogic.com>
 <20191206074052.15557-3-jian.hu@amlogic.com>
 <1j8snhluhg.fsf@starbuckisacylon.baylibre.com>
 <741284be-2ae8-1102-22bc-c510e822c883@amlogic.com>
 <1jk16vb8qm.fsf@starbuckisacylon.baylibre.com>
 <0bc6176f-c0b8-5c31-4c6b-d3686eefe56e@amlogic.com>
Message-ID: <627a8d8b-f049-4cdd-6dd0-5c5acc58a90c@amlogic.com>
Date:   Fri, 20 Dec 2019 15:03:52 +0800
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Hi jerome

On 2019/12/18 16:37, Jian Hu wrote:
> 
> 
> On 2019/12/17 17:29, Jerome Brunet wrote:
>>
>> On Tue 17 Dec 2019 at 09:41, Jian Hu <jian.hu@amlogic.com> wrote:
>>
>>> On 2019/12/12 18:16, Jerome Brunet wrote:
>>>>
>>>> On Fri 06 Dec 2019 at 08:40, Jian Hu <jian.hu@amlogic.com> wrote:
>>>>
>>>>> The A1 PLL design is different with previous SoCs. The PLL
>>>>> internal analog modules Power-on sequence is different
>>>>> with previous, and thus requires a strict register sequence to
>>>>> enable the PLL.
>>>>>
>>>>> Signed-off-by: Jian Hu <jian.hu@amlogic.com>
>>>>> ---
>>>>>    drivers/clk/meson/clk-pll.c | 21 +++++++++++++++++++++
>>>>>    drivers/clk/meson/clk-pll.h |  1 +
>>>>>    drivers/clk/meson/parm.h    |  1 +
>>>>>    3 files changed, 23 insertions(+)
>>>>>
>>>>> diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
>>>>> index ddb1e5634739..4aff31a51589 100644
>>>>> --- a/drivers/clk/meson/clk-pll.c
>>>>> +++ b/drivers/clk/meson/clk-pll.c
>>>>> @@ -318,6 +318,23 @@ static int meson_clk_pll_enable(struct clk_hw 
>>>>> *hw)
>>>>>        struct clk_regmap *clk = to_clk_regmap(hw);
>>>>>        struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
>>>>>    +    /*
>>>>> +     * The A1 design is different with previous SoCs.The PLL
>>>>> +     * internal analog modules Power-on sequence is different with
>>>>> +     * previous, and thus requires a strict register sequence to
>>>>> +     * enable the PLL.
>>>>
>>>> The code does something more, not completly different. This comment is
>>>> not aligned with what the code does
>>> ok, I will correct the comment.
>>>>
>>>>> +     */
>>>>> +    if (MESON_PARM_APPLICABLE(&pll->current_en)) {
>>>>> +        /* Enable the pll */
>>>>> +        meson_parm_write(clk->map, &pll->en, 1);
>>>>> +        udelay(10);
>>>>> +        /* Enable the pll self-adaption module current */
>>>>> +        meson_parm_write(clk->map, &pll->current_en, 1);
>>>>> +        udelay(40);
>>>>> +        meson_parm_write(clk->map, &pll->rst, 1);
>>>>> +        meson_parm_write(clk->map, &pll->rst, 0);
>>>>
>>>> Here you enable the PLL and self adaptation module then reset the PLL.
>>>> However:
>>>> #1 when you enter this function, the PLL should already by in reset
>>>> and disabled
>>>> #2 the code after that will reset the PLL again
>>> For A1 PLLs, There is no reset bit, It will not reset the PLL.
>>> And in V2, you mentioned PARM 'rst' can be used for one toggling, And 
>>> 'rst'
>>> is used for BIT(6) in CTRL2.
>>>
>>
>> oh my ! What is it then ? Why do you need to toggle it ? What does is 
>> do ?
>>
> The PLL enable flow:
>       step1: enable the PLL
>       step2: enable the self adaptation module
>       step3: reset the lock detect module, let the lock detect module 
>             work，And then the PLL will work.
> 
> Toggle the bit 6 in CTRL2 can reset the lock detect module.

#1  I intend to introduce a new PARM 'l_detect', and the 
meson_clk_pll_enable is blow. Please help to review it.

static int meson_clk_pll_enable(struct clk_hw *hw)
{
         struct clk_regmap *clk = to_clk_regmap(hw);
         struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);

         /* do nothing if the PLL is already enabled */
         if (clk_hw_is_enabled(hw))
                 return 0;
         /*
          * Compared with the previous SoCs, self-adaption module current
          * is newly added, keep the new power-on sequence to enable the
          * PLL.
          */
         if (MESON_PARM_APPLICABLE(&pll->current_en)) {
                 /* Enable the pll */
                 meson_parm_write(clk->map, &pll->en, 1);
                 udelay(10);
                 /* Enable the pll self-adaption module current */
                 meson_parm_write(clk->map, &pll->current_en, 1);
                 udelay(40);
                 /* Enable lock detect module */
                 meson_parm_write(clk->map, &pll->l_detect, 1);
                 meson_parm_write(clk->map, &pll->l_detect, 0);
                 goto out;
         }

         /* Make sure the pll is in reset */
         meson_parm_write(clk->map, &pll->rst, 1);

         /* Enable the pll */
         meson_parm_write(clk->map, &pll->en, 1);

         /* Take the pll out reset */
         meson_parm_write(clk->map, &pll->rst, 0);

out:
         if (meson_clk_pll_wait_lock(hw))
                 return -EIO;

         return 0;
}


#2  Add check for PARM 'rst' when
writing to it, the same with frac.

if (MESON_PARM_APPLICABLE(&pll->rst))
    meson_parm_write(clk->map, &pll->rst, 1);


And I have tested it for it, The periphs and hifi pll works well.

Or any good idea about it?

>>> Quote V2 the HIFI PLL init_regs definition：
>>>
>>>
>>> +static const struct reg_sequence a1_hifi_init_regs[] = {
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL1, .def = 0x01800000 },
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL2, .def = 0x00001100 },
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL3, .def = 0x100a1100 },
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL4, .def = 0x00302000 },
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL0, .def = 0x01f18440 },
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL0, .def = 0x11f18440, .delay_us = 
>>> 10 },
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL0, .def = 0x15f18440, .delay_us = 
>>> 40 },
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL2, .def = 0x00001140 },
>>> +    { .reg = ANACTRL_HIFIPLL_CTRL2, .def = 0x00001100 },
>>> +};
>>>
>>> So maybe another new PARM should be defined to avoid the ambiguity.
>>> What do you think about it?
>>
>> This is not the point of my comment Jian !
>>
>> I'm assuming here that you have tested your v4 before sending and that
>> it work (hopefully)
>>
> Yes, it works wells. I have tested the drivers before sending every 
> patchset version.
>> The fact is that with this code, when disabled the bit behind rst
>> (whatever it is) is set. So when you get to enable the bit is already 
>> set.
>> The code you sent does the same as the snip I gave you in the reply.
>>
>> Now, if your PLL is THAT different, maybe it would be best if you could
>> clearly explain how it works, what bit should be set and why. Then we
>> will be able to figure out how the driver has to be restructured.
>>
> the same as 'The PLL enable flow' above
>>>
>>>>
>>>> So if what you submited works, inserting the following should 
>>>> accomplish
>>>> the same thing:
>>>>
>>>> ---8<---
>>>> diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
>>>> index 489092dde3a6..9b38df0a7682 100644
>>>> --- a/drivers/clk/meson/clk-pll.c
>>>> +++ b/drivers/clk/meson/clk-pll.c
>>>> @@ -330,6 +330,13 @@ static int meson_clk_pll_enable(struct clk_hw *hw)
>>>>           /* Enable the pll */
>>>>           meson_parm_write(clk->map, &pll->en, 1);
>>>>
>>>> +       if (MESON_PARM_APPLICABLE(&pll->current_en)) {
>>>> +               udelay(10);
>>>> +               /* Enable the pll self-adaption module current */
>>>> +               meson_parm_write(clk->map, &pll->current_en, 1);
>>>> +               udelay(40);
>>>> +       }
>>>> +
>>>>           /* Take the pll out reset */
>>>>           meson_parm_write(clk->map, &pll->rst, 0);
>>>> --->8---
>>>>
>>>>
>>>>
>>>>
>>>>> +    }
>>>>> +
>>>>>        /* do nothing if the PLL is already enabled */
>>>>>        if (clk_hw_is_enabled(hw))
>>>>>            return 0;
>>>>
>>>> In any case, nothing should be done on the clock before this check
>>>> otherwise you might just break the clock
>>>>
>>> OK, I will put the enabled check ahead.
>>>>> @@ -347,6 +364,10 @@ static void meson_clk_pll_disable(struct 
>>>>> clk_hw *hw)
>>>>>          /* Disable the pll */
>>>>>        meson_parm_write(clk->map, &pll->en, 0);
>>>>> +
>>>>> +    /* Disable PLL internal self-adaption module current */
>>>>> +    if (MESON_PARM_APPLICABLE(&pll->current_en))
>>>>> +        meson_parm_write(clk->map, &pll->current_en, 0);
>>>>>    }
>>>>>      static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned 
>>>>> long
>>>>> rate,
>>>>> diff --git a/drivers/clk/meson/clk-pll.h b/drivers/clk/meson/clk-pll.h
>>>>> index 367efd0f6410..30f039242a65 100644
>>>>> --- a/drivers/clk/meson/clk-pll.h
>>>>> +++ b/drivers/clk/meson/clk-pll.h
>>>>> @@ -36,6 +36,7 @@ struct meson_clk_pll_data {
>>>>>        struct parm frac;
>>>>>        struct parm l;
>>>>>        struct parm rst;
>>>>> +    struct parm current_en;
>>>>>        const struct reg_sequence *init_regs;
>>>>>        unsigned int init_count;
>>>>>        const struct pll_params_table *table;
>>>>> diff --git a/drivers/clk/meson/parm.h b/drivers/clk/meson/parm.h
>>>>> index 3c9ef1b505ce..c53fb26577e3 100644
>>>>> --- a/drivers/clk/meson/parm.h
>>>>> +++ b/drivers/clk/meson/parm.h
>>>>> @@ -20,6 +20,7 @@
>>>>>        (((reg) & CLRPMASK(width, shift)) | ((val) << (shift)))
>>>>>      #define MESON_PARM_APPLICABLE(p)        (!!((p)->width))
>>>>> +#define MESON_PARM_CURRENT(p)            (!!((p)->width))
>>>>
>>>> Why do we need that ?
>>> OK, I will remove it ,and use 'MESON_PARM_APPLICABLE' instead
>>>>
>>>>>      struct parm {
>>>>>        u16    reg_off;
>>>>
>>>> .
>>>>
>>
>> .
>>