Merge tag 'pm-5.18-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull more power management updates from Rafael Wysocki:
 "These update ARM cpufreq drivers, the OPP (Operating Performance
  Points) library and the power management documentation.

  Specifics:

   - Add per core DVFS support for QCom SoC (Bjorn Andersson), convert
     to yaml binding (Manivannan Sadhasivam) and various other fixes to
     the QCom drivers (Luca Weiss).

   - Add OPP table for imx7s SoC (Denys Drozdov) and minor fixes (Stefan
     Agner).

   - Fix CPPC driver's freq/performance conversions (Pierre Gondois).

   - Minor generic cleanups (Yury Norov).

   - Introduce opp-microwatt property to the OPP core, bindings, etc
     (Lukasz Luba).

   - Convert DT bindings to schema format and various related fixes
     (Yassine Oudjana).

   - Expose OPP's OF node in debugfs (Viresh Kumar).

   - Add Intel uncore frequency scaling documentation file to its
     MAINTAINERS entry (Srinivas Pandruvada).

   - Clean up the AMD P-state driver documentation (Jan Engelhardt)"

* tag 'pm-5.18-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (24 commits)
  Documentation: amd-pstate: grammar and sentence structure updates
  dt-bindings: cpufreq: cpufreq-qcom-hw: Convert to YAML bindings
  dt-bindings: dvfs: Use MediaTek CPUFREQ HW as an example
  Documentation: EM: Describe new registration method using DT
  OPP: Add support of "opp-microwatt" for EM registration
  PM: EM: add macro to set .active_power() callback conditionally
  OPP: Add "opp-microwatt" supporting code
  dt-bindings: opp: Add "opp-microwatt" entry in the OPP
  MAINTAINERS: Add additional file to uncore frequency control
  cpufreq: blocklist Qualcomm sc8280xp and sa8540p in cpufreq-dt-platdev
  cpufreq: qcom-hw: Add support for per-core-dcvs
  dt-bindings: power: avs: qcom,cpr: Convert to DT schema
  arm64: dts: qcom: qcs404: Rename CPU and CPR OPP tables
  arm64: dts: qcom: msm8996: Rename cluster OPP tables
  dt-bindings: opp: Convert qcom-nvmem-cpufreq to DT schema
  dt-bindings: opp: qcom-opp: Convert to DT schema
  arm64: dts: qcom: msm8996-mtp: Add msm8996 compatible
  dt-bindings: arm: qcom: Add msm8996 and apq8096 compatibles
  opp: Expose of-node's name in debugfs
  cpufreq: CPPC: Fix performance/frequency conversion
  ...

1 files changed, 21 insertions, 22 deletions

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index db17196266e4b..82d370ae6a4a5 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -303,52 +303,48 @@ static u64 cppc_get_dmi_max_khz(void)
 
 /*
  * If CPPC lowest_freq and nominal_freq registers are exposed then we can
- * use them to convert perf to freq and vice versa
- *
- * If the perf/freq point lies between Nominal and Lowest, we can treat
- * (Low perf, Low freq) and (Nom Perf, Nom freq) as 2D co-ordinates of a line
- * and extrapolate the rest
- * For perf/freq > Nominal, we use the ratio perf:freq at Nominal for conversion
+ * use them to convert perf to freq and vice versa. The conversion is
+ * extrapolated as an affine function passing by the 2 points:
+ *  - (Low perf, Low freq)
+ *  - (Nominal perf, Nominal perf)
  */
 static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu_data,
 					     unsigned int perf)
 {
 	struct cppc_perf_caps *caps = &cpu_data->perf_caps;
+	s64 retval, offset = 0;
 	static u64 max_khz;
 	u64 mul, div;
 
 	if (caps->lowest_freq && caps->nominal_freq) {
-		if (perf >= caps->nominal_perf) {
-			mul = caps->nominal_freq;
-			div = caps->nominal_perf;
-		} else {
-			mul = caps->nominal_freq - caps->lowest_freq;
-			div = caps->nominal_perf - caps->lowest_perf;
-		}
+		mul = caps->nominal_freq - caps->lowest_freq;
+		div = caps->nominal_perf - caps->lowest_perf;
+		offset = caps->nominal_freq - div64_u64(caps->nominal_perf * mul, div);
 	} else {
 		if (!max_khz)
 			max_khz = cppc_get_dmi_max_khz();
 		mul = max_khz;
 		div = caps->highest_perf;
 	}
-	return (u64)perf * mul / div;
+
+	retval = offset + div64_u64(perf * mul, div);
+	if (retval >= 0)
+		return retval;
+	return 0;
 }
 
 static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu_data,
 					     unsigned int freq)
 {
 	struct cppc_perf_caps *caps = &cpu_data->perf_caps;
+	s64 retval, offset = 0;
 	static u64 max_khz;
 	u64  mul, div;
 
 	if (caps->lowest_freq && caps->nominal_freq) {
-		if (freq >= caps->nominal_freq) {
-			mul = caps->nominal_perf;
-			div = caps->nominal_freq;
-		} else {
-			mul = caps->lowest_perf;
-			div = caps->lowest_freq;
-		}
+		mul = caps->nominal_perf - caps->lowest_perf;
+		div = caps->nominal_freq - caps->lowest_freq;
+		offset = caps->nominal_perf - div64_u64(caps->nominal_freq * mul, div);
 	} else {
 		if (!max_khz)
 			max_khz = cppc_get_dmi_max_khz();
@@ -356,7 +352,10 @@ static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu_data,
 		div = max_khz;
 	}
 
-	return (u64)freq * mul / div;
+	retval = offset + div64_u64(freq * mul, div);
+	if (retval >= 0)
+		return retval;
+	return 0;
 }
 
 static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,