drivers/gpu/drm/i915/gt/intel_llc.c

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright © 2019 Intel Corporation
   5  */
   6
   7 #include <linux/cpufreq.h>
   8
   9 #include "i915_drv.h"
  10 #include "intel_gt.h"
  11 #include "intel_llc.h"
  12 #include "intel_sideband.h"
  13
  14 struct ia_constants {
  15         unsigned int min_gpu_freq;
  16         unsigned int max_gpu_freq;
  17
  18         unsigned int min_ring_freq;
  19         unsigned int max_ia_freq;
  20 };
  21
  22 static struct intel_gt *llc_to_gt(struct intel_llc *llc)
  23 {
  24         return container_of(llc, struct intel_gt, llc);
  25 }
  26
  27 static unsigned int cpu_max_MHz(void)
  28 {
  29         struct cpufreq_policy *policy;
  30         unsigned int max_khz;
  31
  32         policy = cpufreq_cpu_get(0);
  33         if (policy) {
  34                 max_khz = policy->cpuinfo.max_freq;
  35                 cpufreq_cpu_put(policy);
  36         } else {
  37                 /*
  38                  * Default to measured freq if none found, PCU will ensure we
  39                  * don't go over
  40                  */
  41                 max_khz = tsc_khz;
  42         }
  43
  44         return max_khz / 1000;
  45 }
  46
  47 static bool get_ia_constants(struct intel_llc *llc,
  48                              struct ia_constants *consts)
  49 {
  50         struct drm_i915_private *i915 = llc_to_gt(llc)->i915;
  51         struct intel_rps *rps = &llc_to_gt(llc)->rps;
  52
  53         if (!HAS_LLC(i915) || IS_DGFX(i915))
  54                 return false;
  55
  56         if (rps->max_freq <= rps->min_freq)
  57                 return false;
  58
  59         consts->max_ia_freq = cpu_max_MHz();
  60
  61         consts->min_ring_freq =
  62                 intel_uncore_read(llc_to_gt(llc)->uncore, DCLK) & 0xf;
  63         /* convert DDR frequency from units of 266.6MHz to bandwidth */
  64         consts->min_ring_freq = mult_frac(consts->min_ring_freq, 8, 3);
  65
  66         consts->min_gpu_freq = rps->min_freq;
  67         consts->max_gpu_freq = rps->max_freq;
  68         if (INTEL_GEN(i915) >= 9) {
  69                 /* Convert GT frequency to 50 HZ units */
  70                 consts->min_gpu_freq /= GEN9_FREQ_SCALER;
  71                 consts->max_gpu_freq /= GEN9_FREQ_SCALER;
  72         }
  73
  74         return true;
  75 }
  76
  77 static void calc_ia_freq(struct intel_llc *llc,
  78                          unsigned int gpu_freq,
  79                          const struct ia_constants *consts,
  80                          unsigned int *out_ia_freq,
  81                          unsigned int *out_ring_freq)
  82 {
  83         struct drm_i915_private *i915 = llc_to_gt(llc)->i915;
  84         const int diff = consts->max_gpu_freq - gpu_freq;
  85         unsigned int ia_freq = 0, ring_freq = 0;
  86
  87         if (INTEL_GEN(i915) >= 9) {
  88                 /*
  89                  * ring_freq = 2 * GT. ring_freq is in 100MHz units
  90                  * No floor required for ring frequency on SKL.
  91                  */
  92                 ring_freq = gpu_freq;
  93         } else if (INTEL_GEN(i915) >= 8) {
  94                 /* max(2 * GT, DDR). NB: GT is 50MHz units */
  95                 ring_freq = max(consts->min_ring_freq, gpu_freq);
  96         } else if (IS_HASWELL(i915)) {
  97                 ring_freq = mult_frac(gpu_freq, 5, 4);
  98                 ring_freq = max(consts->min_ring_freq, ring_freq);
  99                 /* leave ia_freq as the default, chosen by cpufreq */
 100         } else {
 101                 const int min_freq = 15;
 102                 const int scale = 180;
 103
 104                 /*
 105                  * On older processors, there is no separate ring
 106                  * clock domain, so in order to boost the bandwidth
 107                  * of the ring, we need to upclock the CPU (ia_freq).
 108                  *
 109                  * For GPU frequencies less than 750MHz,
 110                  * just use the lowest ring freq.
 111                  */
 112                 if (gpu_freq < min_freq)
 113                         ia_freq = 800;
 114                 else
 115                         ia_freq = consts->max_ia_freq - diff * scale / 2;
 116                 ia_freq = DIV_ROUND_CLOSEST(ia_freq, 100);
 117         }
 118
 119         *out_ia_freq = ia_freq;
 120         *out_ring_freq = ring_freq;
 121 }
 122
 123 static void gen6_update_ring_freq(struct intel_llc *llc)
 124 {
 125         struct drm_i915_private *i915 = llc_to_gt(llc)->i915;
 126         struct ia_constants consts;
 127         unsigned int gpu_freq;
 128
 129         if (!get_ia_constants(llc, &consts))
 130                 return;
 131
 132         /*
 133          * For each potential GPU frequency, load a ring frequency we'd like
 134          * to use for memory access.  We do this by specifying the IA frequency
 135          * the PCU should use as a reference to determine the ring frequency.
 136          */
 137         for (gpu_freq = consts.max_gpu_freq;
 138              gpu_freq >= consts.min_gpu_freq;
 139              gpu_freq--) {
 140                 unsigned int ia_freq, ring_freq;
 141
 142                 calc_ia_freq(llc, gpu_freq, &consts, &ia_freq, &ring_freq);
 143                 sandybridge_pcode_write(i915,
 144                                         GEN6_PCODE_WRITE_MIN_FREQ_TABLE,
 145                                         ia_freq << GEN6_PCODE_FREQ_IA_RATIO_SHIFT |
 146                                         ring_freq << GEN6_PCODE_FREQ_RING_RATIO_SHIFT |
 147                                         gpu_freq);
 148         }
 149 }
 150
 151 void intel_llc_enable(struct intel_llc *llc)
 152 {
 153         gen6_update_ring_freq(llc);
 154 }
 155
 156 void intel_llc_disable(struct intel_llc *llc)
 157 {
 158         /* Currently there is no HW configuration to be done to disable. */
 159 }
 160
 161 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 162 #include "selftest_llc.c"
 163 #endif