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cpufreq: powernv: Report cpu frequency throttling
The power and thermal safety of the system is taken care by an On-Chip-Controller (OCC) which is real-time subsystem embedded within the POWER8 processor. OCC continuously monitors the memory and core temperature, the total system power, state of power supply and fan. The cpu frequency can be throttled by OCC for the following reasons: 1)If a processor crosses its power and temperature limit then OCC will lower its Pmax to reduce the frequency and voltage. 2)If OCC crashes then the system is forced to Psafe frequency. 3)If OCC fails to recover then the kernel is not allowed to do any further frequency changes and the chip will remain in Psafe. The user can see a drop in performance when frequency is throttled and is unaware of throttling. So detect and report such a condition, so the user can check the OCC status to reboot the system or check for power supply or fan failures. The current status of the core is read from Power Management Status Register(PMSR) to check if any of the throttling condition is occurred and the appropriate throttling message is reported. Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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1 changed files with 46 additions and 1 deletions
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@ -34,9 +34,13 @@
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#include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
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#define POWERNV_MAX_PSTATES 256
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#define PMSR_PSAFE_ENABLE (1UL << 30)
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#define PMSR_SPR_EM_DISABLE (1UL << 31)
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#define PMSR_MAX(x) ((x >> 32) & 0xFF)
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#define PMSR_LP(x) ((x >> 48) & 0xFF)
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static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
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static bool rebooting;
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static bool rebooting, throttled;
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/*
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* Note: The set of pstates consists of contiguous integers, the
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@ -294,6 +298,44 @@ static inline unsigned int get_nominal_index(void)
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return powernv_pstate_info.max - powernv_pstate_info.nominal;
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}
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static void powernv_cpufreq_throttle_check(unsigned int cpu)
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{
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unsigned long pmsr;
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int pmsr_pmax, pmsr_lp;
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pmsr = get_pmspr(SPRN_PMSR);
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/* Check for Pmax Capping */
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pmsr_pmax = (s8)PMSR_MAX(pmsr);
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if (pmsr_pmax != powernv_pstate_info.max) {
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throttled = true;
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pr_info("CPU %d Pmax is reduced to %d\n", cpu, pmsr_pmax);
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pr_info("Max allowed Pstate is capped\n");
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}
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/*
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* Check for Psafe by reading LocalPstate
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* or check if Psafe_mode_active is set in PMSR.
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*/
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pmsr_lp = (s8)PMSR_LP(pmsr);
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if ((pmsr_lp < powernv_pstate_info.min) ||
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(pmsr & PMSR_PSAFE_ENABLE)) {
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throttled = true;
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pr_info("Pstate set to safe frequency\n");
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}
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/* Check if SPR_EM_DISABLE is set in PMSR */
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if (pmsr & PMSR_SPR_EM_DISABLE) {
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throttled = true;
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pr_info("Frequency Control disabled from OS\n");
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}
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if (throttled) {
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pr_info("PMSR = %16lx\n", pmsr);
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pr_crit("CPU Frequency could be throttled\n");
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}
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}
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/*
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* powernv_cpufreq_target_index: Sets the frequency corresponding to
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* the cpufreq table entry indexed by new_index on the cpus in the
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@ -307,6 +349,9 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
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if (unlikely(rebooting) && new_index != get_nominal_index())
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return 0;
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if (!throttled)
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powernv_cpufreq_throttle_check(smp_processor_id());
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freq_data.pstate_id = powernv_freqs[new_index].driver_data;
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/*
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