[CPUFREQ] Measure transition latency at driver initialization
The attached patch introduces runtime latency measurement for ICH[234]
based chipsets instead of using CPUFREQ_ETERNAL. It includes
some sanity checks in case the measured value is out of range and
assigns a safe value of 500uSec that should still be enough on
problematics chipsets (current testing report values ~200uSec). The
measurement is currently done in speedstep_get_freqs in order to avoid
further unnecessary transitions and in the hope it'll come handy for SMI
also.
Signed-off-by: Mattia Dongili <malattia@linux.it>
Acked-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Dave Jones <davej@redhat.com>
speedstep-ich.c | 4 ++--
speedstep-lib.c | 32 +++++++++++++++++++++++++++++++-
speedstep-lib.h | 1 +
speedstep-smi.c | 1 +
4 files changed, 35 insertions(+), 3 deletions(-)
diff --git a/arch/i386/kernel/cpu/cpufreq/speedstep-smi.c b/arch/i386/kernel/cpu/cpufreq/speedstep-smi.c
index 2718fb6..28cc5d5 100644
--- a/arch/i386/kernel/cpu/cpufreq/speedstep-smi.c
+++ b/arch/i386/kernel/cpu/cpufreq/speedstep-smi.c
@@ -269,6 +269,7 @@
result = speedstep_get_freqs(speedstep_processor,
&speedstep_freqs[SPEEDSTEP_LOW].frequency,
&speedstep_freqs[SPEEDSTEP_HIGH].frequency,
+ NULL,
&speedstep_set_state);
if (result) {
