References: <20230301183759.16163-1-ddrokosov@sberdevices.ru>
 <20230301183759.16163-2-ddrokosov@sberdevices.ru>
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From:   Jerome Brunet <jbrunet@baylibre.com>
To:     Dmitry Rokosov <ddrokosov@sberdevices.ru>,
        neil.armstrong@linaro.org, mturquette@baylibre.com,
        sboyd@kernel.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, khilman@baylibre.com,
        martin.blumenstingl@googlemail.com
Cc:     jian.hu@amlogic.com, kernel@sberdevices.ru, rockosov@gmail.com,
        linux-amlogic@lists.infradead.org, linux-clk@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v9 1/5] clk: meson: add support for A1 PLL clock ops
Date:   Mon, 06 Mar 2023 12:09:35 +0100
In-reply-to: <20230301183759.16163-2-ddrokosov@sberdevices.ru>
Message-ID: <1jy1oab06v.fsf@starbuckisacylon.baylibre.com>
MIME-Version: 1.0
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On Wed 01 Mar 2023 at 21:37, Dmitry Rokosov <ddrokosov@sberdevices.ru> wrote:

> From: Jian Hu <jian.hu@amlogic.com>
>
> Modern meson PLL IPs are a little bit different from early known PLLs.
> The main difference is located in the init/enable/disable sequences; the
> rate logic is the same.

For the record, I find very odd that PLLs used to have an 'rst' bit in
CTRL0:29 (see g12 for example), this bit goes un-documented in the a1
datasheet, and following SoCs like s4 still have a rst bit, still in
CTRL0:29

I would not be surpized if the rst is actually still there in the a1.
It is just my guess ...

> Compared with the previous SoCs, self-adaption current module
> is newly added for A1, and there is no reset parameter except the
> fixed pll. In A1 PLL, the PLL enable sequence is different, using
> the new power-on sequence to enable the PLL.

Please split this patch:
#1 make the rst optional (if you must)
#2 add the self current adapt param.

Apart from this, it looks good

>
> Signed-off-by: Jian Hu <jian.hu@amlogic.com>
> Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
> ---
>  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 afefeba6e458..56ec2210f1ad 100644
> --- a/drivers/clk/meson/clk-pll.c
> +++ b/drivers/clk/meson/clk-pll.c
> @@ -295,10 +295,14 @@ static int 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);
> +
>  		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);
>  	}
>  
>  	return 0;
> @@ -309,8 +313,11 @@ 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;
>  
> @@ -341,13 +348,34 @@ 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)) {
> +		usleep_range(10, 20);
> +		meson_parm_write(clk->map, &pll->current_en, 1);
> +		usleep_range(40, 50);
> +	};
> +
> +	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;
> @@ -361,10 +389,15 @@ 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);
>  }
>  
>  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;