projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| 2515a526 GKH |
1 | From f0fe3cd7e12d8290c82284b5c8aee723cbd0371a Mon Sep 17 00:00:00 2001 |
| 2 | From: Dirk Brandewie <dirk.j.brandewie@intel.com> | |
| 3 | Date: Thu, 29 May 2014 09:32:23 -0700 | |
| 4 | Subject: intel_pstate: Correct rounding in busy calculation | |
| 5 | ||
| 6 | From: Dirk Brandewie <dirk.j.brandewie@intel.com> | |
| 7 | ||
| 8 | commit f0fe3cd7e12d8290c82284b5c8aee723cbd0371a upstream. | |
| 9 | ||
| 10 | Changing to fixed point math throughout the busy calculation in | |
| 11 | commit e66c1768 (Change busy calculation to use fixed point | |
| 12 | math.) Introduced some inaccuracies by rounding the busy value at two | |
| 13 | points in the calculation. This change removes roundings and moves | |
| 14 | the rounding to the output of the PID where the calculations are | |
| 15 | complete and the value returned as an integer. | |
| 16 | ||
| 17 | Fixes: e66c17683746 (intel_pstate: Change busy calculation to use fixed point math.) | |
| 18 | Reported-by: Doug Smythies <dsmythies@telus.net> | |
| 19 | Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com> | |
| 20 | Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> | |
| 21 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 22 | ||
| 23 | --- | |
| 24 | drivers/cpufreq/intel_pstate.c | 12 +++++++----- | |
| 25 | 1 file changed, 7 insertions(+), 5 deletions(-) | |
| 26 | ||
| 27 | --- a/drivers/cpufreq/intel_pstate.c | |
| 28 | +++ b/drivers/cpufreq/intel_pstate.c | |
| 29 | @@ -40,10 +40,10 @@ | |
| 30 | #define BYT_TURBO_VIDS 0x66d | |
| 31 | ||
| 32 | ||
| 33 | -#define FRAC_BITS 6 | |
| 34 | +#define FRAC_BITS 8 | |
| 35 | #define int_tofp(X) ((int64_t)(X) << FRAC_BITS) | |
| 36 | #define fp_toint(X) ((X) >> FRAC_BITS) | |
| 37 | -#define FP_ROUNDUP(X) ((X) += 1 << FRAC_BITS) | |
| 38 | + | |
| 39 | ||
| 40 | static inline int32_t mul_fp(int32_t x, int32_t y) | |
| 41 | { | |
| 42 | @@ -198,7 +198,10 @@ static signed int pid_calc(struct _pid * | |
| 43 | pid->last_err = fp_error; | |
| 44 | ||
| 45 | result = pterm + mul_fp(pid->integral, pid->i_gain) + dterm; | |
| 46 | - | |
| 47 | + if (result >= 0) | |
| 48 | + result = result + (1 << (FRAC_BITS-1)); | |
| 49 | + else | |
| 50 | + result = result - (1 << (FRAC_BITS-1)); | |
| 51 | return (signed int)fp_toint(result); | |
| 52 | } | |
| 53 | ||
| 54 | @@ -563,7 +566,6 @@ static inline void intel_pstate_calc_bus | |
| 55 | core_pct = div_fp(int_tofp((sample->aperf)), | |
| 56 | int_tofp((sample->mperf))); | |
| 57 | core_pct = mul_fp(core_pct, int_tofp(100)); | |
| 58 | - FP_ROUNDUP(core_pct); | |
| 59 | ||
| 60 | sample->freq = fp_toint( | |
| 61 | mul_fp(int_tofp(cpu->pstate.max_pstate * 1000), core_pct)); | |
| 62 | @@ -609,7 +611,7 @@ static inline int32_t intel_pstate_get_s | |
| 63 | max_pstate = int_tofp(cpu->pstate.max_pstate); | |
| 64 | current_pstate = int_tofp(cpu->pstate.current_pstate); | |
| 65 | core_busy = mul_fp(core_busy, div_fp(max_pstate, current_pstate)); | |
| 66 | - return FP_ROUNDUP(core_busy); | |
| 67 | + return core_busy; | |
| 68 | } | |
| 69 | ||
| 70 | static inline void intel_pstate_adjust_busy_pstate(struct cpudata *cpu) |