linux-kernel - Re: [PATCH V2 06/15] cpufreq: mediatek: Record previous target vproc value

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Date:   Mon, 11 Apr 2022 08:56:54 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rex-BC Chen <rex-bc.chen@...iatek.com>
Cc:     rafael@...nel.org, robh+dt@...nel.org, krzk+dt@...nel.org,
        matthias.bgg@...il.com, jia-wei.chang@...iatek.com,
        roger.lu@...iatek.com, hsinyi@...gle.com, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com,
        "Andrew-sh . Cheng" <andrew-sh.cheng@...iatek.com>
Subject: Re: [PATCH V2 06/15] cpufreq: mediatek: Record previous target vproc
 value

On 08-04-22, 12:58, Rex-BC Chen wrote:
> From: Jia-Wei Chang <jia-wei.chang@...iatek.com>
> 
> We found the buck voltage may not be exactly the same with what we set
> because CPU may share the same buck with other module.
> Therefore, we need to record the previous desired value instead of reading
> it from regulators.
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@...iatek.com>
> Signed-off-by: Jia-Wei Chang <jia-wei.chang@...iatek.com>
> ---
>  drivers/cpufreq/mediatek-cpufreq.c | 31 +++++++++++++++++++-----------
>  1 file changed, 20 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index dc4a87e68940..472f4de29e5f 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -40,6 +40,7 @@ struct mtk_cpu_dvfs_info {
>  	struct list_head list_head;
>  	int intermediate_voltage;
>  	bool need_voltage_tracking;
> +	int old_vproc;

I like prev_vproc better somehow, but it is up to you to name it :)

>  };
>  
>  static LIST_HEAD(dvfs_info_list);
> @@ -190,11 +191,17 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
>  
>  static int mtk_cpufreq_set_voltage(struct mtk_cpu_dvfs_info *info, int vproc)
>  {
> +	int ret;
> +
>  	if (info->need_voltage_tracking)
> -		return mtk_cpufreq_voltage_tracking(info, vproc);
> +		ret = mtk_cpufreq_voltage_tracking(info, vproc);
>  	else
> -		return regulator_set_voltage(info->proc_reg, vproc,
> -					     vproc + VOLT_TOL);
> +		ret = regulator_set_voltage(info->proc_reg, vproc,
> +					    MAX_VOLT_LIMIT);
> +	if (!ret)
> +		info->old_vproc = vproc;
> +
> +	return ret;
>  }
>  
>  static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
> @@ -211,15 +218,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>  
>  	inter_vproc = info->intermediate_voltage;
>  
> -	old_freq_hz = clk_get_rate(cpu_clk);
> -	old_vproc = regulator_get_voltage(info->proc_reg);
> -	if (old_vproc < 0) {
> -		pr_err("%s: invalid Vproc value: %d\n", __func__, old_vproc);
> -		return old_vproc;
> -	}
> -

Why did you move it down from here? I think it was fine to error out
early if voltage isn't available.

>  	freq_hz = freq_table[index].frequency * 1000;
> -
>  	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_hz);
>  	if (IS_ERR(opp)) {
>  		pr_err("cpu%d: failed to find OPP for %ld\n",
> @@ -229,6 +228,16 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
>  	vproc = dev_pm_opp_get_voltage(opp);
>  	dev_pm_opp_put(opp);
>  
> +	old_freq_hz = clk_get_rate(cpu_clk);
> +	old_vproc = info->old_vproc;
> +	if (old_vproc == 0)
> +		old_vproc = regulator_get_voltage(info->proc_reg);
> +	if (old_vproc < 0) {
> +		dev_err(cpu_dev, "%s: invalid Vproc value: %d\n",
> +			__func__, old_vproc);
> +		return old_vproc;
> +	}
> +
>  	/*
>  	 * If the new voltage or the intermediate voltage is higher than the
>  	 * current voltage, scale up voltage first.
> -- 
> 2.18.0

-- 
viresh