[PATCH v3 5/6] cpufreq: powernv: Report Psafe only if PMSR.psafe_mode_active bit is set

Shilpasri G Bhat
2015-05-04T09:01:24Z

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>
---
drivers/cpufreq/powernv-cpufreq.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 9618813..0a59d5b 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -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)
#define OCC_RESET 0
#define OCC_LOAD 1
#define OCC_THROTTLE 2
@@ -316,7 +315,7 @@ 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);

@@ -338,14 +337,9 @@ 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");
}
--
1.9.3