Per Section 8.4.7.1.3 of ACPI 6.2, The platform provides performance
feedback via set of performance counters. To determine the actual
performance level delivered over time, OSPM may read a set of
performance counters from the Reference Performance Counter Register
and the Delivered Performance Counter Register.
OSPM calculates the delivered performance over a given time period by
taking a beginning and ending snapshot of both the reference and
delivered performance counters, and calculating:
delivered_perf = reference_perf X (delta of delivered_perf counter / delta of reference_perf counter).
Implement the above and hook this to the cpufreq->get method.
Signed-off-by: George Cherian <[email protected]>
Acked-by: Viresh Kumar <[email protected]>
---
drivers/cpufreq/cppc_cpufreq.c | 52 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 52 insertions(+)
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index a9d3eec..30f3021 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -296,10 +296,62 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
return ret;
}
+static inline u64 get_delta(u64 t1, u64 t0)
+{
+ if (t1 > t0 || t0 > ~(u32)0)
+ return t1 - t0;
+
+ return (u32)t1 - (u32)t0;
+}
+
+static int cppc_get_rate_from_fbctrs(struct cppc_cpudata *cpu,
+ struct cppc_perf_fb_ctrs fb_ctrs_t0,
+ struct cppc_perf_fb_ctrs fb_ctrs_t1)
+{
+ u64 delta_reference, delta_delivered;
+ u64 reference_perf, delivered_perf;
+
+ reference_perf = fb_ctrs_t0.reference_perf;
+
+ delta_reference = get_delta(fb_ctrs_t1.reference,
+ fb_ctrs_t0.reference);
+ delta_delivered = get_delta(fb_ctrs_t1.delivered,
+ fb_ctrs_t0.delivered);
+
+ /* Check to avoid divide-by zero */
+ if (delta_reference || delta_delivered)
+ delivered_perf = (reference_perf * delta_delivered) /
+ delta_reference;
+ else
+ delivered_perf = cpu->perf_ctrls.desired_perf;
+
+ return cppc_cpufreq_perf_to_khz(cpu, delivered_perf);
+}
+
+static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)
+{
+ struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
+ struct cppc_cpudata *cpu = all_cpu_data[cpunum];
+ int ret;
+
+ ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t0);
+ if (ret)
+ return ret;
+
+ udelay(2); /* 2usec delay between sampling */
+
+ ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t1);
+ if (ret)
+ return ret;
+
+ return cppc_get_rate_from_fbctrs(cpu, fb_ctrs_t0, fb_ctrs_t1);
+}
+
static struct cpufreq_driver cppc_cpufreq_driver = {
.flags = CPUFREQ_CONST_LOOPS,
.verify = cppc_verify_policy,
.target = cppc_cpufreq_set_target,
+ .get = cppc_cpufreq_get_rate,
.init = cppc_cpufreq_cpu_init,
.stop_cpu = cppc_cpufreq_stop_cpu,
.name = "cppc_cpufreq",
--
1.8.3.1
Hi George,
This version looks good. Thanks!
On 7/12/2018 12:07 AM, George Cherian wrote:
> Per Section 8.4.7.1.3 of ACPI 6.2, The platform provides performance
> feedback via set of performance counters. To determine the actual
> performance level delivered over time, OSPM may read a set of
> performance counters from the Reference Performance Counter Register
> and the Delivered Performance Counter Register.
>
> OSPM calculates the delivered performance over a given time period by
> taking a beginning and ending snapshot of both the reference and
> delivered performance counters, and calculating:
>
> delivered_perf = reference_perf X (delta of delivered_perf counter / delta of reference_perf counter).
>
> Implement the above and hook this to the cpufreq->get method.
>
> Signed-off-by: George Cherian <[email protected]>
> Acked-by: Viresh Kumar <[email protected]>
Acked-by: Prashanth Prakash <[email protected]>
On Saturday, July 14, 2018 12:20:43 AM CEST Prakash, Prashanth wrote:
> Hi George,
>
> This version looks good. Thanks!
>
> On 7/12/2018 12:07 AM, George Cherian wrote:
> > Per Section 8.4.7.1.3 of ACPI 6.2, The platform provides performance
> > feedback via set of performance counters. To determine the actual
> > performance level delivered over time, OSPM may read a set of
> > performance counters from the Reference Performance Counter Register
> > and the Delivered Performance Counter Register.
> >
> > OSPM calculates the delivered performance over a given time period by
> > taking a beginning and ending snapshot of both the reference and
> > delivered performance counters, and calculating:
> >
> > delivered_perf = reference_perf X (delta of delivered_perf counter / delta of reference_perf counter).
> >
> > Implement the above and hook this to the cpufreq->get method.
> >
> > Signed-off-by: George Cherian <[email protected]>
> > Acked-by: Viresh Kumar <[email protected]>
> Acked-by: Prashanth Prakash <[email protected]>
>
Patch applied, thanks!