[patch 16/28] HPET: make minimum reprogramming delta useful

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To: <linux-kernel@...>, <stable@...>
Cc: Justin Forbes <jmforbes@...>, Zwane Mwaikambo <zwane@...>, Theodore Ts'o <tytso@...>, Randy Dunlap <rdunlap@...>, Dave Jones <davej@...>, Chuck Wolber <chuckw@...>, Chris Wedgwood <reviews@...>, Michael Krufky <mkrufky@...>, Chuck Ebbert <cebbert@...>, Domenico Andreoli <cavokz@...>, Willy Tarreau <w@...>, Rodrigo Rubira Branco <rbranco@...>, Jake Edge <jake@...>, Eugene Teo <eteo@...>, <torvalds@...>, <akpm@...>, <alan@...>, Thomas Gleixner <tglx@...>, Ingo Molnar <mingo@...>
Date: Monday, October 6, 2008 - 7:17 pm

2.6.25-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Thomas Gleixner <tglx@linutronix.de>

commit 7cfb0435330364f90f274a26ecdc5f47f738498c upstream

The minimum reprogramming delta was hardcoded in HPET ticks,
which is stupid as it does not work with faster running HPETs.
The C1E idle patches made this prominent on AMD/RS690 chipsets,
where the HPET runs with 25MHz. Set it to 5us which seems to be
a reasonable value and fixes the problems on the bug reporters
machines. We have a further sanity check now in the clock events,
which increases the delta when it is not sufficient.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Tested-by: Dmitry Nezhevenko <dion@inhex.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 arch/x86/kernel/hpet.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -222,8 +222,8 @@ static void hpet_legacy_clockevent_regis
 	/* Calculate the min / max delta */
 	hpet_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,
 							   &hpet_clockevent);
-	hpet_clockevent.min_delta_ns = clockevent_delta2ns(0x30,
-							   &hpet_clockevent);
+	/* 5 usec minimum reprogramming delta. */
+	hpet_clockevent.min_delta_ns = 5000;
 
 	/*
 	 * Start hpet with the boot cpu mask and make it

-- 
--
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Messages in current thread:
[patch 00/28] 2.6.25-stable review, Greg KH, (Mon Oct 6, 7:16 pm)
[patch 28/28] udp: Fix rcv socket locking, Greg KH, (Mon Oct 6, 7:18 pm)
[patch 24/28] niu: panic on reset, Greg KH, (Mon Oct 6, 7:17 pm)
[patch 16/28] HPET: make minimum reprogramming delta useful, Greg KH, (Mon Oct 6, 7:17 pm)
[patch 09/28] rtc: fix deadlock, Greg KH, (Mon Oct 6, 7:17 pm)
[patch 07/28] ACPI: Fix thermal shutdowns, Greg KH, (Mon Oct 6, 7:17 pm)
[patch 03/28] pxa2xx_spi: chipselect bugfixes, Greg KH, (Mon Oct 6, 7:17 pm)
[patch 02/28] pxa2xx_spi: dma bugfixes, Greg KH, (Mon Oct 6, 7:17 pm)
Re: [patch 02/28] pxa2xx_spi: dma bugfixes, Ned Forrester, (Mon Oct 6, 8:15 pm)
[patch 01/28] USB: fix hcd interrupt disabling, Greg KH, (Mon Oct 6, 7:16 pm)