linux-kernel - Re: [PATCH v3 06/11] clk: qcom: Fix .set_rate to handle alpha PLLs w/wo dynamic update

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Date:   Wed, 2 Nov 2016 14:54:45 -0700
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Rajendra Nayak <rnayak@...eaurora.org>
Cc:     mturquette@...libre.com, linux-clk@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        tdas@...eaurora.org
Subject: Re: [PATCH v3 06/11] clk: qcom: Fix .set_rate to handle alpha PLLs
 w/wo dynamic update

On 09/29, Rajendra Nayak wrote:
> Alpha PLLs which do not support dynamic update feature
> need to be explicitly disabled before a rate change.
> The ones which do support dynamic update do so within a
> single vco range, so add a min/max freq check for such
> PLLs so they fall in the vco range.
> 
> Signed-off-by: Taniya Das <tdas@...eaurora.org>

Is Taniya the author?

> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
> ---
>  drivers/clk/qcom/clk-alpha-pll.c | 49 +++++++++++++++++++++++++++++++++-------
>  drivers/clk/qcom/clk-alpha-pll.h |  3 +++
>  2 files changed, 44 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
> index 89c7fdb..6f90a86 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.c
> +++ b/drivers/clk/qcom/clk-alpha-pll.c
> @@ -382,16 +382,41 @@ clk_alpha_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
>  static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
>  				  unsigned long prate)
>  {
> +	bool enabled;
>  	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
>  	const struct pll_vco *vco;
>  	u32 l, off = pll->offset;
>  	u64 a;
>  
>  	rate = alpha_pll_round_rate(rate, prate, &l, &a);
> -	vco = alpha_pll_find_vco(pll, rate);
> -	if (!vco) {
> -		pr_err("alpha pll not in a valid vco range\n");
> -		return -EINVAL;
> +	enabled = clk_hw_is_enabled(hw);
> +
> +	if (pll->flags & SUPPORTS_DYNAMIC_UPDATE) {
> +		/*
> +		 * PLLs which support dynamic updates support one single
> +		 * vco range, between min_rate and max_rate supported
> +		 */
> +		if (rate < pll->min_rate || rate > pll->max_rate) {
> +			pr_err("alpha pll rate outside supported min/max range\n");
> +			return -EINVAL;
> +		}
> +	} else {
> +		/*
> +		 * All alpha PLLs which do not support dynamic update,
> +		 * should be disabled before a vco update.
> +		 */
> +		if (enabled)
> +			hw->init->ops->disable(hw);

Please just call the function directly instead of going through
the init structure.

> +
> +		vco = alpha_pll_find_vco(pll, rate);
> +		if (!vco) {
> +			pr_err("alpha pll not in a valid vco range\n");
> +			return -EINVAL;
> +		}
> +
> +		regmap_update_bits(pll->clkr.regmap, off + PLL_USER_CTL,
> +				   PLL_VCO_MASK << PLL_VCO_SHIFT,
> +				   vco->val << PLL_VCO_SHIFT);
>  	}
>  
>  	regmap_write(pll->clkr.regmap, off + PLL_L_VAL, l);
> diff --git a/drivers/clk/qcom/clk-alpha-pll.h b/drivers/clk/qcom/clk-alpha-pll.h
> index d6e1ee2..e43a9c0 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.h
> +++ b/drivers/clk/qcom/clk-alpha-pll.h
> @@ -37,8 +37,11 @@ struct clk_alpha_pll {
>  #define SUPPORTS_OFFLINE_REQ	BIT(0)
>  #define SUPPORTS_16BIT_ALPHA	BIT(1)
>  #define SUPPORTS_FSM_MODE	BIT(2)
> +#define SUPPORTS_DYNAMIC_UPDATE	BIT(3)
>  	u8 flags;
>  
> +	unsigned long min_rate;
> +	unsigned long max_rate;

Document these?

>  	struct clk_regmap clkr;
>  };
>  

-- 
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