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

From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-samsung-soc@vger.kernel.org,
	Viresh Kumar <viresh.kumar@linaro.org>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Nishanth Menon <nm@ti.com>, Stephen Boyd <sboyd@kernel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Dave Gerlach <d-gerlach@ti.com>, Wolfram Sang <wsa@the-dreams.de>
Subject: Re: [PATCH 0/2] cpufreq/opp: rework regulator initialization
Date: Fri, 8 Feb 2019 12:47:06 +0100	[thread overview]
Message-ID: <87302853-74cc-8eeb-6bd4-6338746e0738@samsung.com> (raw)
In-Reply-To: <20190208110053.GA7913@e107155-lin>

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