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Date: Wed, 18 Dec 2019 16:37:49 +0800
From: Jian Hu <jian.hu@...ogic.com>
To: Jerome Brunet <jbrunet@...libre.com>,
Neil Armstrong <narmstrong@...libre.com>
CC: Kevin Hilman <khilman@...libre.com>, Rob Herring <robh@...nel.org>,
Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Qiufang Dai <qiufang.dai@...ogic.com>,
Jianxin Pan <jianxin.pan@...ogic.com>,
Victor Wan <victor.wan@...ogic.com>,
Chandle Zou <chandle.zou@...ogic.com>,
<linux-clk@...r.kernel.org>, <linux-amlogic@...ts.infradead.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH v4 2/6] clk: meson: add support for A1 PLL clock ops
On 2019/12/17 17:29, Jerome Brunet wrote:
>
> On Tue 17 Dec 2019 at 09:41, Jian Hu <jian.hu@...ogic.com> wrote:
>
>> On 2019/12/12 18:16, Jerome Brunet wrote:
>>>
>>> On Fri 06 Dec 2019 at 08:40, Jian Hu <jian.hu@...ogic.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@...ogic.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.
>> 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;
>>>
>>> .
>>>
>
> .
>
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