The patch titled
Mark TSC on GeodeLX reliable
has been added to the -mm tree. Its filename is
mark-tsc-on-geodelx-reliable.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Mark TSC on GeodeLX reliable
From: Marcelo Tosatti <marcelo@xxxxxxxxx>
The Geode can safely use the TSC for highres, since:
1) Does not support frequency scaling,
2) The TSC _does_ count when the CPU is halted. Furthermore, the Geode
supports a mode called "suspension on halt", where Suspend mode (which
interacts with the power management states) is entered. TSC counting
during suspend mode is controlled by bit 8 of the Bus Controller
Configuration Register #0 (thanks Tom!).
3) no SMP :)
Check if "RTSC counts during suspension" and remove the requirement for
verification, so the clocksource code can safely select it as an timesource
for the highres timers subsystem.
Signed-off-by: Marcelo Tosatti <marcelo@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Cc: john stultz <johnstul@xxxxxxxxxx>
Cc: Roman Zippel <zippel@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/kernel/tsc.c | 20 ++++++++++++++++++++
include/asm-i386/msr.h | 3 +++
2 files changed, 23 insertions(+)
diff -puN arch/i386/kernel/tsc.c~mark-tsc-on-geodelx-reliable arch/i386/kernel/tsc.c
--- a/arch/i386/kernel/tsc.c~mark-tsc-on-geodelx-reliable
+++ a/arch/i386/kernel/tsc.c
@@ -364,6 +364,25 @@ __cpuinit int unsynchronized_tsc(void)
return tsc_unstable;
}
+/*
+ * Geode_LX - the OLPC CPU has a possibly a very reliable TSC
+ */
+#ifdef CONFIG_MGEODE_LX
+/* RTSC counts during suspend */
+#define RTSC_SUSP 0x100
+
+static void __init check_geode_tsc_reliable(void)
+{
+ unsigned long val;
+
+ rdmsrl(MSR_GEODE_BUSCONT_CONF0, val);
+ if ((val & RTSC_SUSP))
+ clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
+}
+#else
+static inline void check_geode_tsc_reliable(void) { }
+#endif
+
static int __init init_tsc_clocksource(void)
{
@@ -372,6 +391,7 @@ static int __init init_tsc_clocksource(v
dmi_check_system(bad_tsc_dmi_table);
unsynchronized_tsc();
+ check_geode_tsc_reliable();
current_tsc_khz = tsc_khz;
clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
clocksource_tsc.shift);
diff -puN include/asm-i386/msr.h~mark-tsc-on-geodelx-reliable include/asm-i386/msr.h
--- a/include/asm-i386/msr.h~mark-tsc-on-geodelx-reliable
+++ a/include/asm-i386/msr.h
@@ -310,4 +310,7 @@ void wrmsr_on_cpu(unsigned int cpu, u32
#define MSR_CORE_PERF_GLOBAL_CTRL 0x38f
#define MSR_CORE_PERF_GLOBAL_OVF_CTRL 0x390
+/* Geode defined MSRs */
+#define MSR_GEODE_BUSCONT_CONF0 0x1900
+
#endif /* __ASM_MSR_H */
_
Patches currently in -mm which might be from marcelo@xxxxxxxxx are
mark-tsc-on-geodelx-reliable.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
