Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=07190a08eef3666a8687070226c8d403c1d548b7
Commit:     07190a08eef3666a8687070226c8d403c1d548b7
Parent:     5d8b34fdcb384161552d01ee8f34af5ff11f9684
Author:     Marcelo Tosatti <[EMAIL PROTECTED]>
AuthorDate: Fri Feb 16 01:27:44 2007 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Feb 16 08:13:58 2007 -0800

    [PATCH] Mark TSC on GeodeLX reliable
    
    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 <[EMAIL PROTECTED]>
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Cc: john stultz <[EMAIL PROTECTED]>
    Cc: Roman Zippel <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 arch/i386/kernel/tsc.c |   20 ++++++++++++++++++++
 include/asm-i386/msr.h |    3 +++
 2 files changed, 23 insertions(+), 0 deletions(-)

diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index 22931d2..3082a41 100644
--- a/arch/i386/kernel/tsc.c
+++ b/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(void)
                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 --git a/include/asm-i386/msr.h b/include/asm-i386/msr.h
index 609a389..6db40d0 100644
--- a/include/asm-i386/msr.h
+++ b/include/asm-i386/msr.h
@@ -307,4 +307,7 @@ static inline void wrmsrl (unsigned long msr, unsigned long 
long val)
 #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 */
-
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to