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cpufreq: powernv: Use PMCR to verify global and local pstate
As fast_switch() may get called with interrupt disable mode, we cannot hold a mutex to update the global_pstate_info. So currently, fast_switch() does not update the global_pstate_info and it will end up with stale data whenever pstate is updated through fast_switch(). As the gpstate_timer can fire after fast_switch() has updated the pstates, the timer handler cannot rely on the cached values of local and global pstate and needs to read it from the PMCR. Only gpstate_timer_handler() is affected by the stale cached pstate data beacause either fast_switch() or target_index() routines will be called for a given govenor, but gpstate_timer can fire after the governor has changed to schedutil. Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com> Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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parent
60c9efb8f7
commit
20b15b7663
1 changed files with 26 additions and 10 deletions
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@ -42,6 +42,10 @@
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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 LPSTATE_SHIFT 48
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#define GPSTATE_SHIFT 56
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#define GET_LPSTATE(x) (((x) >> LPSTATE_SHIFT) & 0xFF)
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#define GET_GPSTATE(x) (((x) >> GPSTATE_SHIFT) & 0xFF)
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#define MAX_RAMP_DOWN_TIME 5120
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/*
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@ -592,7 +596,8 @@ void gpstate_timer_handler(unsigned long data)
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{
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struct cpufreq_policy *policy = (struct cpufreq_policy *)data;
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struct global_pstate_info *gpstates = policy->driver_data;
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int gpstate_idx;
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int gpstate_idx, lpstate_idx;
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unsigned long val;
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unsigned int time_diff = jiffies_to_msecs(jiffies)
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- gpstates->last_sampled_time;
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struct powernv_smp_call_data freq_data;
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@ -600,21 +605,36 @@ void gpstate_timer_handler(unsigned long data)
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if (!spin_trylock(&gpstates->gpstate_lock))
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return;
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/*
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* If PMCR was last updated was using fast_swtich then
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* We may have wrong in gpstate->last_lpstate_idx
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* value. Hence, read from PMCR to get correct data.
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*/
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val = get_pmspr(SPRN_PMCR);
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freq_data.gpstate_id = (s8)GET_GPSTATE(val);
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freq_data.pstate_id = (s8)GET_LPSTATE(val);
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if (freq_data.gpstate_id == freq_data.pstate_id) {
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reset_gpstates(policy);
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spin_unlock(&gpstates->gpstate_lock);
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return;
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}
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gpstates->last_sampled_time += time_diff;
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gpstates->elapsed_time += time_diff;
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freq_data.pstate_id = idx_to_pstate(gpstates->last_lpstate_idx);
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if ((gpstates->last_gpstate_idx == gpstates->last_lpstate_idx) ||
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(gpstates->elapsed_time > MAX_RAMP_DOWN_TIME)) {
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if (gpstates->elapsed_time > MAX_RAMP_DOWN_TIME) {
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gpstate_idx = pstate_to_idx(freq_data.pstate_id);
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reset_gpstates(policy);
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gpstates->highest_lpstate_idx = gpstate_idx;
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} else {
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lpstate_idx = pstate_to_idx(freq_data.pstate_id);
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gpstate_idx = calc_global_pstate(gpstates->elapsed_time,
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gpstates->highest_lpstate_idx,
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gpstates->last_lpstate_idx);
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lpstate_idx);
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}
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freq_data.gpstate_id = idx_to_pstate(gpstate_idx);
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gpstates->last_gpstate_idx = gpstate_idx;
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gpstates->last_lpstate_idx = lpstate_idx;
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/*
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* If local pstate is equal to global pstate, rampdown is over
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* So timer is not required to be queued.
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@ -622,10 +642,6 @@ void gpstate_timer_handler(unsigned long data)
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if (gpstate_idx != gpstates->last_lpstate_idx)
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queue_gpstate_timer(gpstates);
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freq_data.gpstate_id = idx_to_pstate(gpstate_idx);
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gpstates->last_gpstate_idx = pstate_to_idx(freq_data.gpstate_id);
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gpstates->last_lpstate_idx = pstate_to_idx(freq_data.pstate_id);
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spin_unlock(&gpstates->gpstate_lock);
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/* Timer may get migrated to a different cpu on cpu hot unplug */
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