Hi Shilpa, On 27 March 2015 at 00:11, Shilpasri G Bhat <shilpa.b...@linux.vnet.ibm.com> wrote: > Cpu frequency can be throttled due to failures of components like OCC, > power supply and fan. It can also be throttled due to temperature and > power limit. We can detect the throttling by checking 1)if max frequency
Add these points in separate lines please, with a space after ). Its not readable this way.. > is reduced, 2)if the core is put to safe frequency 3)if the SPR based > frequency management is disabled. All these three points refer to the state CPU has shifted to ? Sorry it wasn't clear to the outsiders :), perhaps some more detail on why CPU would have done that. > 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. So, what do we want to do on throttling? Just print a warning? Is that enough? What if CPU gets heated up to a point that it burns up ? > Signed-off-by: Shilpasri G Bhat <shilpa.b...@linux.vnet.ibm.com> > --- > Changes from V1: Removed unused value of PMCR register > > drivers/cpufreq/powernv-cpufreq.c | 39 > ++++++++++++++++++++++++++++++++++++++- > 1 file changed, 38 insertions(+), 1 deletion(-) > > diff --git a/drivers/cpufreq/powernv-cpufreq.c > b/drivers/cpufreq/powernv-cpufreq.c > index 2dfd4fd..4837eed 100644 > --- a/drivers/cpufreq/powernv-cpufreq.c > +++ b/drivers/cpufreq/powernv-cpufreq.c > @@ -36,7 +36,7 @@ > #define POWERNV_MAX_PSTATES 256 > > static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; > -static bool rebooting; > +static bool rebooting, throttled; > > /* > * Note: The set of pstates consists of contiguous integers, the > @@ -294,6 +294,40 @@ static inline unsigned int get_nominal_index(void) > return powernv_pstate_info.max - powernv_pstate_info.nominal; > } > > +static void powernv_cpufreq_throttle_check(unsigned int cpu) > +{ > + unsigned long pmsr; > + int pmsr_pmax, pmsr_lp; > + > + pmsr = get_pmspr(SPRN_PMSR); > + > + /* Check for Pmax Capping */ > + pmsr_pmax = (s8)((pmsr >> 32) & 0xFF); u8 ? > + if (pmsr_pmax != powernv_pstate_info.max) { > + throttled = true; > + pr_warn("Cpu %d Pmax is reduced to %d\n", cpu, pmsr_pmax); > + } > + > + /* Check for Psafe by reading LocalPstate > + * or check if Psafe_mode_active- 34th bit is set in PMSR. > + */ Proper multi-line comment format is: /* * .... */ > + pmsr_lp = (s8)((pmsr >> 48) & 0xFF); > + if ((pmsr_lp < powernv_pstate_info.min) || ((pmsr >> 30) & 1)) { > + throttled = true; > + pr_warn("Cpu %d in Psafe %d PMSR[34]=%lx\n", cpu, > + pmsr_lp, ((pmsr >> 30) & 1)); > + } > + > + /* Check if SPR_EM_DISABLED- 33rd bit is set in PMSR */ > + if ((pmsr >> 31) & 1) { > + throttled = true; > + pr_warn("Frequency management disabled cpu %d PMSR[33]=%lx\n", > + cpu, ((pmsr >> 31) & 1)); > + } > + if (throttled) > + pr_warn("Cpu Frequency is throttled\n"); > +} > + > /* > * powernv_cpufreq_target_index: Sets the frequency corresponding to > * the cpufreq table entry indexed by new_index on the cpus in the > @@ -307,6 +341,9 @@ static int powernv_cpufreq_target_index(struct > cpufreq_policy *policy, > if (unlikely(rebooting) && new_index != get_nominal_index()) > return 0; > > + if (!throttled) > + powernv_cpufreq_throttle_check(smp_processor_id()); And CPU can't come out of throttling again ? > + > freq_data.pstate_id = powernv_freqs[new_index].driver_data; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/