linux-kernel - Re: [PATCH V3 05/15] cpufreq: mediatek: Add opp notification support

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Message-ID: <6f5e44e3-c690-5e39-bbb6-fb6bd0091099@collabora.com>
Date:   Fri, 15 Apr 2022 14:24:16 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Rex-BC Chen <rex-bc.chen@...iatek.com>, rafael@...nel.org,
        viresh.kumar@...aro.org, robh+dt@...nel.org, krzk+dt@...nel.org,
        matthias.bgg@...il.com
Cc:     jia-wei.chang@...iatek.com, roger.lu@...iatek.com,
        hsinyi@...gle.com, khilman@...libre.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 V3 05/15] cpufreq: mediatek: Add opp notification support

Il 15/04/22 07:59, Rex-BC Chen ha scritto:
> From: "Andrew-sh.Cheng" <andrew-sh.cheng@...iatek.com>
> 
>  From this opp notifier, cpufreq should listen to opp notification and do
> proper actions when receiving events of disable and voltage adjustment.
> 
> One of the user for this opp notifier is MediaTek SVS.
> The MediaTek Smart Voltage Scaling (SVS) is a hardware which calculates
> suitable SVS bank voltages to OPP voltage table.
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@...iatek.com>
> Signed-off-by: Jia-Wei Chang <jia-wei.chang@...iatek.com>
> Signed-off-by: Rex-BC Chen <rex-bc.chen@...iatek.com>
> ---
>   drivers/cpufreq/mediatek-cpufreq.c | 93 +++++++++++++++++++++++++++---
>   1 file changed, 85 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index fa8b193bf27b..221f249f8d21 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -41,6 +41,11 @@ struct mtk_cpu_dvfs_info {
>   	int intermediate_voltage;
>   	bool need_voltage_tracking;
>   	int pre_vproc;
> +	/* Avoid race condition for regulators between notify and policy */
> +	struct mutex reg_lock;
> +	struct notifier_block opp_nb;
> +	int opp_cpu;

This should be unsigned int because:
1. A negative CPU number is impossible;
2. The only usage is as a parameter of cpufreq_cpu_get(unsigned int cpu).

Please change this to unsigned int, after which:

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>