intel_pstate: fix PCT_TO_HWP macro

Commit Message

Kristen Carlson Accardi Sept. 9, 2015, 6:41 p.m. UTC

PCT_TO_HWP does not take the actual range of pstates exported
by HWP_CAPABILITIES in account, and is broken on most platforms.
Remove the macro and set the min and max pstate for hwp by
determining the range and adjusting by the min and max percent
limits values.

Signed-off-by: Kristen Carlson Accardi <[e-mail]>
---
 drivers/cpufreq/intel_pstate.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

Patch

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index fcb929e..c4bf8d8 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -260,24 +260,31 @@  static inline void update_turbo_state(void)
 		 cpu->pstate.max_pstate == cpu->pstate.turbo_pstate);
 }
 
-#define PCT_TO_HWP(x) (x * 255 / 100)
 static void intel_pstate_hwp_set(void)
 {
-	int min, max, cpu;
-	u64 value, freq;
+	int min, hw_min, max, hw_max, cpu, range, adj_range;
+	u64 value, cap;
+
+	rdmsrl(MSR_HWP_CAPABILITIES, cap);
+	hw_min = HWP_LOWEST_PERF(cap);
+	hw_max = HWP_HIGHEST_PERF(cap);
+	range = hw_max - hw_min;
 
 	get_online_cpus();
 
 	for_each_online_cpu(cpu) {
 		rdmsrl_on_cpu(cpu, MSR_HWP_REQUEST, &value);
-		min = PCT_TO_HWP(limits.min_perf_pct);
+		adj_range = limits.min_perf_pct * range / 100;
+		min = hw_min + adj_range;
 		value &= ~HWP_MIN_PERF(~0L);
 		value |= HWP_MIN_PERF(min);
 
-		max = PCT_TO_HWP(limits.max_perf_pct);
+		adj_range = limits.max_perf_pct * range / 100;
+		max = hw_min + adj_range;
 		if (limits.no_turbo) {
-			rdmsrl( MSR_HWP_CAPABILITIES, freq);
-			max = HWP_GUARANTEED_PERF(freq);
+			hw_max = HWP_GUARANTEED_PERF(cap);
+			if (hw_max < max)
+				max = hw_max;
 		}
 
 		value &= ~HWP_MAX_PERF(~0L);