On 05/04/2015 02:24 PM, Shilpasri G Bhat wrote:
> 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.b...@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");
>       }
> 

Reviewed-by: Preeti U Murthy <pre...@linux.vnet.ibm.com>

--
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/

Reply via email to