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cpufreq: powernv: Report Psafe only if PMSR.psafe_mode_active bit is set 

On a reset cycle of OCC, although the system retires from safe
frequency state the local pstate is not restored to Pmin or last
requested pstate. Now if the cpufreq governor initiates a pstate
change, the local pstate will be in Psafe and we will be reporting a
false positive when we are not throttled.

So in powernv_cpufreq_throttle_check() remove the condition which
checks if local pstate is less than Pmin while checking for Psafe
frequency. If the cpus are forced to Psafe then PMSR.psafe_mode_active
bit will be set. So, when OCCs become active this bit will be cleared.
Let us just rely on this bit for reporting throttling.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Shilpasri G Bhat 2015-07-16 13:34:22 +05:30 committed by Rafael J. Wysocki
parent 735366fc40
commit 3dd3ebe5bb
1 changed files with 3 additions and 9 deletions
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12
drivers/cpufreq/powernv-cpufreq.c
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@ -39,7 +39,6 @@
#define PMSR_PSAFE_ENABLE (1UL << 30)
#define PMSR_SPR_EM_DISABLE (1UL << 31)
#define PMSR_MAX(x) ((x >> 32) & 0xFF)
#define PMSR_LP(x) ((x >> 48) & 0xFF)
static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
static bool rebooting, throttled, occ_reset;
@ -313,7 +312,7 @@ static void powernv_cpufreq_throttle_check(void *data)
{
unsigned int cpu = smp_processor_id();
unsigned long pmsr;
int pmsr_pmax, pmsr_lp, i;
int pmsr_pmax, i;
pmsr = get_pmspr(SPRN_PMSR);
@ -335,14 +334,9 @@ static void powernv_cpufreq_throttle_check(void *data)
chips[i].id, pmsr_pmax);
}
/*
* Check for Psafe by reading LocalPstate
* or check if Psafe_mode_active is set in PMSR.
*/
/* Check if Psafe_mode_active is set in PMSR. */
next:
pmsr_lp = (s8)PMSR_LP(pmsr);
if ((pmsr_lp < powernv_pstate_info.min) ||
(pmsr & PMSR_PSAFE_ENABLE)) {
if (pmsr & PMSR_PSAFE_ENABLE) {
throttled = true;
pr_info("Pstate set to safe frequency\n");
}