linux-kernel - Re: [PATCH 5/5] intel_idle: Add S0ix validation

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Date:	Sat, 4 Jun 2016 13:22:13 +0100
From:	Alan <gnomes@...rguk.ukuu.org.uk>
To:	"dbasehore ." <dbasehore@...omium.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Linux-pm mailing list <linux-pm@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 5/5] intel_idle: Add S0ix validation

> I would expect those IP blocks to do nothing and not block lower power
> states if the firmware is not loaded. If that is not the case, I think
> that should be fixed such that those lower power states are at least
> available during suspend (if not during runtime). If your Skylake+
> system is not entering S0ix during freeze, I consider that a bug that
> needs to be addressed.

You would assume wrongly. Several parts of the system do their own
power management so if present need to have a driver loaded. Graphics
is the example everyone is familiar with but ADSP audio and ISH are two
others.

> configs, that's their decision. As I said, this does nothing in the
> !CONFIG_INTEL_PMC_CORE case, but if a finer level config is warranted,
> I can add that.

IMHO it belongs as a config item because it has a power cost, and you
can't turn it off without enabling debugfs when it's compiled in.

> I would prefer if others used this more, since there would be better
> debug coverage and I would have to fix fewer bugs.

I'd be more concerned about getting 10,000 emails bisecting the warning
to your commit 8)

Alan