[PATCH 3.14 211/228] intel_pstate: remove setting P state to MAX on init

Greg Kroah-Hartman
2014-06-04T23:55:03Z

From: Dirk Brandewie <dirk.j.brandewie@intel.com>

commit d40a63c45b506b0681918d7c62a15cc9d48c8681 upstream.

Setting the P state of the core to max at init time is a hold over
from early implementation of intel_pstate where intel_pstate disabled
cpufreq and loaded VERY early in the boot sequence. This was to
ensure that intel_pstate did not affect boot time. This in not needed
now that intel_pstate is a cpufreq driver.

Removing this covers the case where a CPU has gone through a manual
CPU offline/online cycle and the P state is set to MAX on init and the
CPU immediately goes idle. Due to HW coordination the P state request
on the idle CPU will drag all cores to MAX P state until the load is
reevaluated when to core goes non-idle.

Reported-by: Patrick Marlier <patrick.marlier@gmail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/cpufreq/intel_pstate.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)

--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -555,12 +555,7 @@ static void intel_pstate_get_cpu_pstates

if (pstate_funcs.get_vid)
pstate_funcs.get_vid(cpu);
-
- /*
- * goto max pstate so we don't slow up boot if we are built-in if we are
- * a module we will take care of it during normal operation
- */
- intel_pstate_set_pstate(cpu, cpu->pstate.max_pstate);
+ intel_pstate_set_pstate(cpu, cpu->pstate.min_pstate);
}

static inline void intel_pstate_calc_busy(struct cpudata *cpu,
@@ -706,11 +701,6 @@ static int intel_pstate_init_cpu(unsigne
cpu = all_cpu_data[cpunum];

intel_pstate_get_cpu_pstates(cpu);
- if (!cpu->pstate.current_pstate) {
- all_cpu_data[cpunum] = NULL;
- kfree(cpu);
- return -ENODATA;
- }

cpu->cpu = cpunum;

@@ -721,7 +711,6 @@ static int intel_pstate_init_cpu(unsigne
cpu->timer.expires = jiffies + HZ/100;
intel_pstate_busy_pid_reset(cpu);
intel_pstate_sample(cpu);
- intel_pstate_set_pstate(cpu, cpu->pstate.max_pstate);

add_timer_on(&cpu->timer, cpunum);