linux-kernel - [RFC PATCH 0/5] Add support for S3 non-stop TSC support.

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Date:	Mon, 21 Jan 2013 14:38:40 +0800
From:	Feng Tang <feng.tang@...el.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	John Stultz <john.stultz@...aro.org>,
	Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...ux.intel.com>, x86@...nel.org,
	Len Brown <lenb@...nel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	linux-kernel@...r.kernel.org
Cc:	Feng Tang <feng.tang@...el.com>
Subject: [RFC PATCH 0/5] Add support for S3 non-stop TSC support. 

Hi All,

On some new Intel Atom processors (Penwell and Cloverview), there is
a feature that the TSC won't stop S3, say the TSC value won't be
reset to 0 after resume. This feature makes TSC a more reliable
clocksource and could benefit the timekeeping code during system
suspend/resume cycles.

The enabling efforts include adding new flags for this feature, 
modifying clocksource.c and timekeeping.c to support and utilizing
it.

One remaining question is inside the timekeeping_resume(), we don't
know if it is called by resuming from suspend(s2ram) or from
hibernate(s2disk), as there is no easy way to check it currently.
But it doesn't hurt as these Penwell/Cloverview platforms only have
S3 state, and no S4.

Please help to review them, thanks!

- Feng

---------

Feng Tang (5):
  x86: Add cpu capability flag X86_FEATURE_TSC_S3_NOTSTOP
  clocksource: Add new feature flag CLOCK_SOURCE_SUSPEND_NOTSTOP
  x86: tsc: Add support for new S3_NOTSTOP feature
  clocksource: Enlarge the maxim time interval when configuring the
    scale and shift
  timekeeping: Add support for clocksource which doesn't stop during
    suspend

 arch/x86/include/asm/cpufeature.h |    1 +
 arch/x86/kernel/cpu/intel.c       |   12 ++++++++++++
 arch/x86/kernel/tsc.c             |    6 +++++-
 include/linux/clocksource.h       |    1 +
 kernel/time/clocksource.c         |    6 +++---
 kernel/time/timekeeping.c         |   23 ++++++++++++++++++-----
 6 files changed, 40 insertions(+), 9 deletions(-)

-- 
1.7.9.5

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