[PATCH] Mark TSC on GeodeLX reliable
authorMarcelo Tosatti <marcelo@kvack.org>
Fri, 16 Feb 2007 09:27:44 +0000 (01:27 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Fri, 16 Feb 2007 16:13:58 +0000 (08:13 -0800)
commit07190a08eef3666a8687070226c8d403c1d548b7
tree20a9f7e9b6bf925a6721f88e438ec551fa8ce992
parent5d8b34fdcb384161552d01ee8f34af5ff11f9684
[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 <marcelo@kvack.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/i386/kernel/tsc.c
include/asm-i386/msr.h