From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Viresh Kumar <viresh.kumar@linaro.org>,
ulf.hansson@linaro.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>
Cc: linux-pm@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
Stephen Boyd <sboyd@kernel.org>, Nishanth Menon <nm@ti.com>,
nks@flawful.org, georgi.djakov@linaro.org,
Stephan Gerhold <stephan@gerhold.net>,
linux-kernel@vger.kernel.org,
'Linux Samsung SOC' <linux-samsung-soc@vger.kernel.org>,
Krzysztof Kozlowski <krzk@kernel.org>
Subject: Re: [PATCH V2 2/2] cpufreq: dt: Refactor initialization to handle probe deferral properly
Date: Tue, 1 Sep 2020 10:57:09 +0200 [thread overview]
Message-ID: <00a87bad-f750-b08c-4ccb-545b90dd87fc@samsung.com> (raw)
In-Reply-To: <f75c61f193f396608d592ae2a9938264d582c038.1598260050.git.viresh.kumar@linaro.org>
Hi Viresh
On 24.08.2020 11:09, Viresh Kumar wrote:
> From: Stephan Gerhold <stephan@gerhold.net>
>
> cpufreq-dt is currently unable to handle -EPROBE_DEFER properly
> because the error code is not propagated for the cpufreq_driver->init()
> callback. Instead, it attempts to avoid the situation by temporarily
> requesting all resources within resources_available() and releasing them
> again immediately after. This has several disadvantages:
>
> - Whenever we add something like interconnect handling to the OPP core
> we need to patch cpufreq-dt to request these resources early.
>
> - resources_available() is only run for CPU0, but other clusters may
> eventually depend on other resources that are not available yet.
> (See FIXME comment removed by this commit...)
>
> - All resources need to be looked up several times.
>
> Now that the OPP core can propagate -EPROBE_DEFER during initialization,
> it would be nice to avoid all that trouble and just propagate its error
> code when necessary.
>
> This commit refactors the cpufreq-dt driver to initialize private_data
> before registering the cpufreq driver. We do this by iterating over
> all possible CPUs and ensure that all resources are initialized:
>
> 1. dev_pm_opp_get_opp_table() ensures the OPP table is allocated
> and initialized with clock and interconnects.
>
> 2. dev_pm_opp_set_regulators() requests the regulators and assigns
> them to the OPP table.
>
> 3. We call dev_pm_opp_of_get_sharing_cpus() early so that we only
> initialize the OPP table once for each shared policy.
>
> With these changes, we actually end up saving a few lines of code,
> the resources are no longer looked up multiple times and everything
> should be much more robust.
>
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> [ Viresh: Use list_head structure for maintaining the list and minor
> changes ]
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
This patch landed in linux-next about a week ago. It introduces a
following warning on Samsung Exnyos3250 SoC:
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
1000000000, volt: 1150000, enabled: 1. New: freq: 1000000000, volt:
1150000, enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
900000000, volt: 1112500, enabled: 1. New: freq: 900000000, volt:
1112500, enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
800000000, volt: 1075000, enabled: 1. New: freq: 800000000, volt:
1075000, enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
700000000, volt: 1037500, enabled: 1. New: freq: 700000000, volt:
1037500, enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
600000000, volt: 1000000, enabled: 1. New: freq: 600000000, volt:
1000000, enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
500000000, volt: 962500, enabled: 1. New: freq: 500000000, volt: 962500,
enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
400000000, volt: 925000, enabled: 1. New: freq: 400000000, volt: 925000,
enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
300000000, volt: 887500, enabled: 1. New: freq: 300000000, volt: 887500,
enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
200000000, volt: 850000, enabled: 1. New: freq: 200000000, volt: 850000,
enabled: 1
cpu cpu1: _opp_is_duplicate: duplicate OPPs detected. Existing: freq:
100000000, volt: 850000, enabled: 1. New: freq: 100000000, volt: 850000,
enabled: 1
I've checked a bit and this is related to the fact that Exynos3250 SoC
use OPP-v1 table. Is this intentional? It is not a problem to convert it
to OPP-v2 and mark OPP table as shared, but this is a kind of a regression.
> ...
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
next prev parent reply other threads:[~2020-09-01 8:57 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 9:09 [PATCH V2 1/2] opp: Allow dev_pm_opp_get_opp_table() to return -EPROBE_DEFER Viresh Kumar
2020-08-24 9:09 ` [PATCH V2 2/2] cpufreq: dt: Refactor initialization to handle probe deferral properly Viresh Kumar
[not found] ` <CGME20200901085708eucas1p231ccacd7b41685ece92ee21e3b726f28@eucas1p2.samsung.com>
2020-09-01 8:57 ` Marek Szyprowski [this message]
2020-09-01 9:45 ` Viresh Kumar
2020-09-01 10:05 ` Marek Szyprowski
2020-09-01 10:12 ` Viresh Kumar
2020-10-13 9:47 ` Geert Uytterhoeven
2020-10-13 9:56 ` Viresh Kumar
2020-10-14 16:40 ` Geert Uytterhoeven
2020-10-16 5:03 ` Viresh Kumar
2020-10-16 6:44 ` Geert Uytterhoeven
2020-10-16 8:07 ` Viresh Kumar
2020-10-27 16:29 ` Geert Uytterhoeven
2020-10-28 5:48 ` Viresh Kumar
2020-10-28 9:49 ` Geert Uytterhoeven
2020-10-28 9:52 ` Viresh Kumar
2020-08-24 9:17 ` [PATCH V2 1/2] opp: Allow dev_pm_opp_get_opp_table() to return -EPROBE_DEFER Krzysztof Kozlowski
2020-08-24 11:08 ` Ulf Hansson
2020-08-24 11:39 ` Stephan Gerhold
2020-10-15 18:05 ` Sudeep Holla
2020-10-16 4:24 ` Viresh Kumar
2020-10-16 6:00 ` Sudeep Holla
2020-10-16 11:12 ` Sudeep Holla
2020-10-16 15:28 ` Stephan Gerhold
2020-10-19 4:58 ` Viresh Kumar
2020-10-19 9:17 ` Sudeep Holla
2020-10-19 9:24 ` Viresh Kumar
2020-10-19 10:12 ` Sudeep Holla
2020-10-19 10:35 ` Viresh Kumar
2020-10-19 14:10 ` Sudeep Holla
2020-10-20 5:05 ` Viresh Kumar
2020-10-20 5:54 ` Viresh Kumar
2020-10-20 9:37 ` Sudeep Holla
2020-10-20 9:41 ` Viresh Kumar
2020-10-20 9:52 ` Sudeep Holla
2020-10-20 9:59 ` Viresh Kumar
2020-10-27 22:24 ` Guenter Roeck
2020-10-28 4:06 ` Viresh Kumar
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