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[3.16.y-ckt,stable] Patch "x86/platform: Fix Geode LX timekeeping in the generic x86 build" has been added to staging queue

Message ID 1445894058-32567-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Oct. 26, 2015, 9:14 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    x86/platform: Fix Geode LX timekeeping in the generic x86 build

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.19.8-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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From 7e9a28a8e1c86244697b6d12502773ab37f0b58a Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw2@infradead.org>
Date: Wed, 16 Sep 2015 14:10:03 +0100
Subject: x86/platform: Fix Geode LX timekeeping in the generic x86 build

commit 03da3ff1cfcd7774c8780d2547ba0d995f7dc03d upstream.

In 2007, commit 07190a08eef36 ("Mark TSC on GeodeLX reliable")
bypassed verification of the TSC on Geode LX. However, this code
(now in the check_system_tsc_reliable() function in
arch/x86/kernel/tsc.c) was only present if CONFIG_MGEODE_LX was
set.

OpenWRT has recently started building its generic Geode target
for Geode GX, not LX, to include support for additional
platforms. This broke the timekeeping on LX-based devices,
because the TSC wasn't marked as reliable:
https://dev.openwrt.org/ticket/20531

By adding a runtime check on is_geode_lx(), we can also include
the fix if CONFIG_MGEODEGX1 or CONFIG_X86_GENERIC are set, thus
fixing the problem.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: Andres Salomon <dilinger@queued.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <marcelo@kvack.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1442409003.131189.87.camel@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 arch/x86/kernel/tsc.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

--
1.9.1
diff mbox

Patch

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 5054497..21187eb 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -21,6 +21,7 @@ 
 #include <asm/hypervisor.h>
 #include <asm/nmi.h>
 #include <asm/x86_init.h>
+#include <asm/geode.h>

 unsigned int __read_mostly cpu_khz;	/* TSC clocks / usec, not used here */
 EXPORT_SYMBOL(cpu_khz);
@@ -1004,15 +1005,17 @@  EXPORT_SYMBOL_GPL(mark_tsc_unstable);

 static void __init check_system_tsc_reliable(void)
 {
-#ifdef CONFIG_MGEODE_LX
-	/* RTSC counts during suspend */
+#if defined(CONFIG_MGEODEGX1) || defined(CONFIG_MGEODE_LX) || defined(CONFIG_X86_GENERIC)
+	if (is_geode_lx()) {
+		/* RTSC counts during suspend */
 #define RTSC_SUSP 0x100
-	unsigned long res_low, res_high;
+		unsigned long res_low, res_high;

-	rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high);
-	/* Geode_LX - the OLPC CPU has a very reliable TSC */
-	if (res_low & RTSC_SUSP)
-		tsc_clocksource_reliable = 1;
+		rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high);
+		/* Geode_LX - the OLPC CPU has a very reliable TSC */
+		if (res_low & RTSC_SUSP)
+			tsc_clocksource_reliable = 1;
+	}
 #endif
 	if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE))
 		tsc_clocksource_reliable = 1;