linux-kernel - Re: [PATCH 0/5] Add suspend-to-idle validation for Intel SoCs

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Date:	Sat, 11 Jun 2016 22:31:11 +0200
From:	Pavel Machek <pavel@....cz>
To:	"dbasehore ." <dbasehore@...omium.org>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Linux-pm mailing list <linux-pm@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 0/5] Add suspend-to-idle validation for Intel SoCs

On Tue 2016-06-07 17:07:21, dbasehore . wrote:
> On Tue, Jun 7, 2016 at 12:46 AM, Pavel Machek <pavel@....cz> wrote:
> > On Wed 2016-06-01 21:33:24, dbasehore@...omium.org wrote:
> >> From: Derek Basehore <dbasehore@...omium.org>
> >>
> >> This patch set adds support for catching errors when entering freeze
> >> on Intel Skylake SoCs. Support for this can be added to newer SoCs in
> >> later patches.
> >>
> >> Verification is done by waking up the CPU once every X (default 10)
> >> seconds to check the residency of S0ix. This can't be verified before
> >> attempting to enter S0ix through mwait, so we have to repeatedly
> >> verify entry into that state. Successfully entering S0ix is no
> >> guarantee that it will be entered on the next attempt, so we have to
> >> schedule another check. This has a minimal power impact of <1% of the
> >> total system power on our systems.
> >
> > Dunno. Should this be protected with something like CONFIG_TEST_SLEEP?
> > People probably don't want this for production...
> >
> 
> That depends, if you switch to using suspend to idle instead of
> suspend to RAM, would you rather not catch power bugs due to
> misconfigured hardware in production?

> I agree that it shouldn't be on by default since freeze shouldn't fail
> because some IP on the SoC doesn't have firmware loaded (this happens
> with i915), but I was just going to leave it off by default instead of
> adding yet another config option for a small feature.

I'd rather have testing features optional. In 2 years, hopefully the
drivers are debugged, and people can set this to off...

									Pavel


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