Re: [PATCH v7 2/5] clk: meson: add support for A1 PLL clock ops

Jerome Brunet
2020-02-18T09:05:49Z

On Mon 10 Feb 2020 at 07:11, Jian Hu <jian.hu@amlogic.com> wrote:

> Hi Jerome
>
> Thanks for your suggestions.
>
> On 2020/2/4 18:24, Jerome Brunet wrote:
>>
>> On Mon 20 Jan 2020 at 04:49, Jian Hu <jian.hu@amlogic.com> wrote:
>>
>>> Compared with the previous SoCs, self-adaption current module
>>> is newly added for A1, and there is no reset parm except the
>>> fixed pll. In A1 PLL, the PLL enable sequence is different, using
>>> the new power-on sequence to enable the PLL.
>>
>> Things are getting clearer thanks to Martin's suggestions and I can
>> understand what your driver is doing now
>>
>> However, I still have a problem with the fact that 2 different pll types
>> are getting intertwined in this driver. Parameters mandatory to one is
>> made optional to the other. Nothing clearly shows which needs what and
>> the combinatorial are quickly growing.
>>
>> Apparently the only real difference is in enable/disable, So I would
>> prefer if the a1 had dedicated function for these ops.
>>
>> I suppose you'll have to submit clk_hw_enable() and clk_hw_disable()
>> to the framework to call the appropriate ops dependind on the SoC.
>>
> I am confused here.
> What does clk_hw_is_enabled/clk_hw_enable/clk_hw_disable use here?

I'm asking you to make different callback for .enable() and .disable().
The .set_rate() callback of this driver needs to turn off and on the
clock, so it needs to call the appropriate one.

To do so, you should go through a clk_hw_xxxxx() function.

>
> clk_hw_is_enabled is intend to check a parm's existence? But
> clk_hw_is_enabled which is existed in CCF to check a PLL is locked or
> not. Maybe I understand wrong about your suggestions.
>
> Could you list a example for clk_hw_enable and clk_hw_disable function
> implementation?

drivers/clk/clk.c:523 : clk_hw_is_enabled()

clk_hw_enable() and clk_hw_disable() so you'll need to implement these
one and submit them.

>>>
>>> Signed-off-by: Jian Hu <jian.hu@amlogic.com>
>>> Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
>>> ---
>>> drivers/clk/meson/clk-pll.c | 47 +++++++++++++++++++++++++++++++------
>>> drivers/clk/meson/clk-pll.h | 2 ++
>>> 2 files changed, 42 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
>>> index ddb1e5634739..10926291440f 100644
>>> --- a/drivers/clk/meson/clk-pll.c
>>> +++ b/drivers/clk/meson/clk-pll.c
>>> @@ -283,10 +283,14 @@ static void meson_clk_pll_init(struct clk_hw *hw)
>>> struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
>>> if (pll->init_count) {
>>> - meson_parm_write(clk->map, &pll->rst, 1);
>>> + if (MESON_PARM_APPLICABLE(&pll->rst))
>>> + meson_parm_write(clk->map, &pll->rst, 1);
>>> +
>>
>> replace by
>> enabled = clk_hw_is_enabled(hw)
>> if (enabled)
>> clk_hw_disable(hw)
>>
> clk_hw_is_enabled here is used to check 'pll->rst'?
>>> regmap_multi_reg_write(clk->map, pll->init_regs,
>>> pll->init_count);
>>> - meson_parm_write(clk->map, &pll->rst, 0);
>>> +
>>> + if (MESON_PARM_APPLICABLE(&pll->rst))
>>> + meson_parm_write(clk->map, &pll->rst, 0);
>>
>> /* restore if necessary */
>> if (enabled)
>> clk_hw_enable(hw)
>>
>>> }
>>> }
>>> @@ -295,8 +299,11 @@ static int meson_clk_pll_is_enabled(struct clk_hw
>>> *hw)
>>> struct clk_regmap *clk = to_clk_regmap(hw);
>>> struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
>>> - if (meson_parm_read(clk->map, &pll->rst) ||
>>> - !meson_parm_read(clk->map, &pll->en) ||
>>> + if (MESON_PARM_APPLICABLE(&pll->rst) &&
>>> + meson_parm_read(clk->map, &pll->rst))
>>> + return 0;
>>> +
>>> + if (!meson_parm_read(clk->map, &pll->en) ||
>>> !meson_parm_read(clk->map, &pll->l))
>>> return 0;
>>
>> I suppose the pll can't be locked if it was in reset, so we could drop
>> the check on `rst` entirely to simplify the function
>>
> OK, I will drop 'rst' check.
>>> @@ -323,13 +330,34 @@ static int meson_clk_pll_enable(struct clk_hw
>>> *hw)
>>> return 0;
>>> /* Make sure the pll is in reset */
>>> - meson_parm_write(clk->map, &pll->rst, 1);
>>> + if (MESON_PARM_APPLICABLE(&pll->rst))
>>> + 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);
>>> + if (MESON_PARM_APPLICABLE(&pll->rst))
>>> + meson_parm_write(clk->map, &pll->rst, 0);
>>> +
>>> + /*
>>> + * Compared with the previous SoCs, self-adaption current module
>>> + * is newly added for A1, keep the new power-on sequence to enable the
>>> + * PLL. The sequence is:
>>> + * 1. enable the pll, delay for 10us
>>> + * 2. enable the pll self-adaption current module, delay for 40us
>>> + * 3. enable the lock detect module
>>> + */
>>> + if (MESON_PARM_APPLICABLE(&pll->current_en)) {
>>> + udelay(10);
>>> + meson_parm_write(clk->map, &pll->current_en, 1);
>>> + udelay(40);
>>> + };
>>> +
>>> + if (MESON_PARM_APPLICABLE(&pll->l_detect)) {
>>> + meson_parm_write(clk->map, &pll->l_detect, 1);
>>> + meson_parm_write(clk->map, &pll->l_detect, 0);
>>> + }
>>> if (meson_clk_pll_wait_lock(hw))
>>> return -EIO;
>>> @@ -343,10 +371,15 @@ static void meson_clk_pll_disable(struct clk_hw *hw)
>>> struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
>>> /* Put the pll is in reset */
>>> - meson_parm_write(clk->map, &pll->rst, 1);
>>> + if (MESON_PARM_APPLICABLE(&pll->rst))
>>> + meson_parm_write(clk->map, &pll->rst, 1);
>>> /* Disable the pll */
>>> meson_parm_write(clk->map, &pll->en, 0);
>>> +
>>> + /* Disable PLL internal self-adaption current module */
>>> + if (MESON_PARM_APPLICABLE(&pll->current_en))
>>> + meson_parm_write(clk->map, &pll->current_en, 0);
>>> }
>>
>> With the above clarified, it should be easy to properly split the
>> functions between the legacy type and the a1 type.
>>
>> You'll need to update meson_clk_pll_set_rate() to call
>> - clk_hw_is_enabled()
>> - clk_hw_enable() and clk_hw_disable() (again, you'll need to add
>> those in the framework first)
>>
>>> 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..a2228c0fdce5 100644
>>> --- a/drivers/clk/meson/clk-pll.h
>>> +++ b/drivers/clk/meson/clk-pll.h
>>> @@ -36,6 +36,8 @@ struct meson_clk_pll_data {
>>> struct parm frac;
>>> struct parm l;
>>> struct parm rst;
>>> + struct parm current_en;
>>> + struct parm l_detect;
>>> const struct reg_sequence *init_regs;
>>> unsigned int init_count;
>>> const struct pll_params_table *table;
>>
>> .
>>