linux-kernel - Re: [PATCH] cpufreq: mediatek: change transition delay for MT8186

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Message-ID: <20230829083521.trec3rjjmscqp2dw@vireshk-i7>
Date:   Tue, 29 Aug 2023 14:05:21 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Chun-Jen Tseng (曾俊仁) 
        <Chun-Jen.Tseng@...iatek.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "sumitg@...dia.com" <sumitg@...dia.com>,
        "sanjayc@...dia.com" <sanjayc@...dia.com>,
        "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH] cpufreq: mediatek: change transition delay for MT8186

On 29-08-23, 14:01, Viresh Kumar wrote:
> Why exactly does the kernel crash here ? Any idea ?

Also note that cpufreq core has enough locking in place to make sure
two ->target_index() function calls don't run in parallel for the same
policy.

What may be happening in your case is that you are configuring a
common entity (CCI) from both the policies and there is no locking in
place to take care of the races.

-- 
viresh