From: Ulf Hansson <ulf.hansson@linaro.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Kevin Hilman <khilman@linaro.org>,
Tomasz Figa <tomasz.figa@gmail.com>,
Philipp Zabel <philipp.zabel@gmail.com>,
Russell King <linux@arm.linux.org.uk>,
Mark Brown <broonie@kernel.org>, Wolfram Sang <wsa@the-dreams.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Jack Dai <jack.dai@rock-chips.com>,
Jinkun Hong <jinkun.hong@rock-chips.com>
Subject: Re: [PATCH 0/4] PM / Domains: Fix race conditions during boot
Date: Thu, 2 Oct 2014 12:07:43 +0200 [thread overview]
Message-ID: <CAPDyKFpyGRtrRA4BuvkSHhvZ+DnMFYh-jS2k8VLKo1VMGSSgDw@mail.gmail.com> (raw)
In-Reply-To: <2138676.3O5bPrOhTg@vostro.rjw.lan>
[...]
>> 1) Even if CONFIG_PM_RUNTIME is enabled, we have no mechanism to use
>> for drivers/subsystems to bring device's PM domains into powered state
>> before doing ->probe(). Well, of course, they could use
>> pm_runtime_get_sync() in that path, but that's just not the common
>> practice and there are good reasons to why.
>>
>> So, even if we figured out a solution for drivers/subsystems to
>> support the above, it's not reasonable to think we can adopt each of
>> them shortly. We need a fix in genpd.
>
> My concern is that if we change the default behavior today, people will see
> power regressions on some platforms. Surely, power regressions are not as
> bad as functional regressions, but we can't say we don't care.
>
> Did you consider adding some handling of that to driver_probe_device()?
> We do a barrier in there, but conceivably we could do more if a PM domain
> is attached.
Forgot to comment on this.
I think the problem with such approach would be that the PM domain
hasn't yet been attached to the device, since that happens at
bus->probe().
Maybe we could find a solution which only affect the buses though and
not the drivers. But I need to think a bit more on this, before I can
post a proposal.
Kind regards
Uffe
prev parent reply other threads:[~2014-10-02 10:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-30 12:43 [PATCH 0/4] PM / Domains: Fix race conditions during boot Ulf Hansson
2014-09-30 12:43 ` [PATCH 1/4] PM / Domains: Remove pm_genpd_dev_need_restore() API Ulf Hansson
2014-09-30 13:21 ` Geert Uytterhoeven
2014-09-30 18:07 ` Kevin Hilman
2014-09-30 12:43 ` [PATCH 2/4] ARM: exynos: Ensure PM domains are powered at initialization Ulf Hansson
2014-09-30 18:33 ` Kevin Hilman
2014-10-01 11:23 ` Tomasz Figa
2014-10-01 12:45 ` Ulf Hansson
2014-09-30 12:43 ` [PATCH 3/4] PM / Domains: Expect PM domains being " Ulf Hansson
2014-09-30 13:24 ` Geert Uytterhoeven
2014-09-30 18:21 ` Kevin Hilman
2014-10-01 11:09 ` Ulf Hansson
2014-09-30 18:30 ` Kevin Hilman
2014-10-01 10:47 ` Ulf Hansson
2014-09-30 12:43 ` [PATCH 4/4] PM / Domains: Enforce PM domains to stay powered during boot Ulf Hansson
2014-09-30 20:08 ` [PATCH 0/4] PM / Domains: Fix race conditions " Rafael J. Wysocki
2014-10-01 7:35 ` Ulf Hansson
2014-10-01 20:31 ` Rafael J. Wysocki
2014-10-02 9:28 ` Ulf Hansson
2014-10-02 10:07 ` Ulf Hansson [this message]
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