linux-kernel - Re: [PATCH v4 6/6] clk: qcom: ipq4019: Add the cpu clock frequency change notifier

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Message-ID: <20161221235627.GI8288@codeaurora.org>
Date:   Wed, 21 Dec 2016 15:56:27 -0800
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Abhishek Sahu <absahu@...eaurora.org>
Cc:     andy.gross@...aro.org, david.brown@...aro.org,
        mturquette@...libre.com, robh+dt@...nel.org, mark.rutland@....com,
        varada@...eaurora.org, pradeepb@...eaurora.org,
        snlakshm@...eaurora.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v4 6/6] clk: qcom: ipq4019: Add the cpu clock frequency
 change notifier

On 11/25, Abhishek Sahu wrote:
> @@ -1736,13 +1737,55 @@ static int clk_cpu_div_set_rate(struct clk_hw *hw, unsigned long rate,
>  };
>  MODULE_DEVICE_TABLE(of, gcc_ipq4019_match_table);
>  
> +/* Contains index for safe clock during APSS freq change */
> +static int gcc_ipq4019_cpu_safe_parent;
> +static int
> +gcc_ipq4019_cpu_clk_notifier_fn(struct notifier_block *nb,
> +				unsigned long action, void *data)
> +{
> +	int err = 0;
> +
> +	if (action == PRE_RATE_CHANGE)
> +		err = clk_rcg2_ops.set_parent(&apps_clk_src.clkr.hw,
> +					      gcc_ipq4019_cpu_safe_parent);

Why can't we hardcode this? It's not like this safe parent is
going to change across boards.

> +
> +	return notifier_from_errno(err);
> +}
> +
> +static struct notifier_block gcc_ipq4019_cpu_clk_notifier = {
> +	.notifier_call = gcc_ipq4019_cpu_clk_notifier_fn,
> +};
> +
>  static int gcc_ipq4019_probe(struct platform_device *pdev)
>  {
> -	return qcom_cc_probe(pdev, &gcc_ipq4019_desc);
> +	int err;
> +
> +	err = qcom_cc_probe(pdev, &gcc_ipq4019_desc);
> +	if (err)
> +		return err;
> +
> +	gcc_ipq4019_cpu_safe_parent = qcom_find_src_index(&apps_clk_src.clkr.hw,
> +						apps_clk_src.parent_map,
> +						P_FEPLL500);
> +	if (gcc_ipq4019_cpu_safe_parent < 0)
> +		err = gcc_ipq4019_cpu_safe_parent;

Then we don't need to do this.

> +
> +	if (!err)
> +		err = clk_notifier_register(apps_clk_src.clkr.hw.clk,
> +				      &gcc_ipq4019_cpu_clk_notifier);
> +
> +	return err;
> +}
> +

-- 
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