linux-kernel - Re: [PATCH 0/2] cpufreq/opp: rework regulator initialization

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Message-ID: <87302853-74cc-8eeb-6bd4-6338746e0738@samsung.com>
Date:   Fri, 8 Feb 2019 12:47:06 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Dave Gerlach <d-gerlach@...com>,
        Wolfram Sang <wsa@...-dreams.de>
Subject: Re: [PATCH 0/2] cpufreq/opp: rework regulator initialization

Hi Sudeep,

On 2019-02-08 12:00, Sudeep Holla wrote:
> On Thu, Feb 07, 2019 at 01:22:25PM +0100, Marek Szyprowski wrote:
>> Dear All,
>>
>> This is a scenario that triggers the above issue:
> [...]
>> 1. system disables non-boot cpu's at the end of system suspend procedure,
>> 2. this in turn deinitializes cpufreq drivers for the disabled cpus,
>> 3. early in the system resume procedure all cpus are got back to online
>>    state,
>> 4. this in turn causes cpufreq to be initialized for the newly onlined
>>    cpus,
>> 5. cpufreq-dt acquires all its resources (clocks, regulators) during
>>    ->init() callback,
> This is strictly not just restricted to cpufreq-dt, but to any driver
> supporting multiple policies. So we need a generic fix not just
> cpufreq-dt specific.

Could you point which other driver needs similar fix? Here in cpufreq-dt
the problem was caused by using regulator api (indirectly) from
->init(). All other drivers, which have regulators support, are for old,
obsolete, uni-processor systems, which don't have the problem of
secondary cpu suspend during system suspend/resume cycle.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland