calc-gtf-cvt.cpp

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * Copyright 2006-2012 Red Hat, Inc.
   4  * Copyright 2018-2021 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   5  *
   6  * Author: Adam Jackson <ajax@nwnk.net>
   7  * Maintainer: Hans Verkuil <hverkuil-cisco@xs4all.nl>
   8  */
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <math.h>
  13 #include <time.h>
  14
  15 #include "edid-decode.h"
  16
  17 #define CELL_GRAN 8.0
  18 #define MARGIN_PERC 1.8
  19 #define GTF_MIN_PORCH 1.0
  20 #define GTF_V_SYNC_RQD 3.0
  21 #define GTF_H_SYNC_PERC 8.0
  22 #define GTF_MIN_VSYNC_BP 550.0
  23
  24 timings edid_state::calc_gtf_mode(unsigned h_pixels, unsigned v_lines,
  25                                   double ip_freq_rqd, bool int_rqd,
  26                                   enum gtf_ip_parm ip_parm, bool margins_rqd,
  27                                   bool secondary, double C, double M, double K, double J)
  28 {
  29         timings t = {};
  30         /* C' and M' are part of the Blanking Duty Cycle computation */
  31         double C_PRIME = ((C - J) * K / 256.0) + J;
  32         double M_PRIME = K / 256.0 * M;
  33
  34         double h_pixels_rnd = round(h_pixels / CELL_GRAN) * CELL_GRAN;
  35         double v_lines_rnd = int_rqd ? round(v_lines / 2.0) : v_lines;
  36         unsigned hor_margin = margins_rqd ?
  37                 round(h_pixels_rnd * MARGIN_PERC / 100.0 / CELL_GRAN)  * CELL_GRAN : 0;
  38         unsigned vert_margin = margins_rqd ? round(MARGIN_PERC / 100.0 * v_lines_rnd) : 0;
  39         double interlace = int_rqd ? 0.5 : 0;
  40         double total_active_pixels = h_pixels_rnd + hor_margin * 2;
  41
  42         t.hact = h_pixels_rnd;
  43         t.vact = v_lines;
  44         t.interlaced = int_rqd;
  45
  46         double pixel_freq;
  47         double h_blank_pixels;
  48         double total_pixels;
  49         double v_sync_bp;
  50
  51         if (ip_parm == gtf_ip_vert_freq) {
  52                 // vertical frame frequency (Hz)
  53                 double v_field_rate_rqd = int_rqd ? ip_freq_rqd * 2 : ip_freq_rqd;
  54                 double h_period_est = ((1.0 / v_field_rate_rqd) - GTF_MIN_VSYNC_BP / 1000000.0) /
  55                         (v_lines_rnd + vert_margin * 2 + GTF_MIN_PORCH + interlace) * 1000000.0;
  56                 v_sync_bp = round(GTF_MIN_VSYNC_BP / h_period_est);
  57                 double total_v_lines = v_lines_rnd + vert_margin * 2 +
  58                         v_sync_bp + interlace + GTF_MIN_PORCH;
  59                 double v_field_rate_est = 1.0 / h_period_est / total_v_lines * 1000000.0;
  60                 double h_period = h_period_est / (v_field_rate_rqd / v_field_rate_est);
  61                 double ideal_duty_cycle = C_PRIME - (M_PRIME * h_period / 1000.0);
  62                 h_blank_pixels = round(total_active_pixels * ideal_duty_cycle /
  63                                        (100.0 - ideal_duty_cycle) /
  64                                        (2 * CELL_GRAN)) * 2 * CELL_GRAN;
  65                 total_pixels = total_active_pixels + h_blank_pixels;
  66                 pixel_freq = total_pixels / h_period;
  67         } else if (ip_parm == gtf_ip_hor_freq) {
  68                 // horizontal frequency (kHz)
  69                 double h_freq = ip_freq_rqd;
  70                 v_sync_bp = round(GTF_MIN_VSYNC_BP * h_freq / 1000.0);
  71                 double ideal_duty_cycle = C_PRIME - (M_PRIME / h_freq);
  72                 h_blank_pixels = round(total_active_pixels * ideal_duty_cycle /
  73                                        (100.0 - ideal_duty_cycle) /
  74                                        (2 * CELL_GRAN)) * 2 * CELL_GRAN;
  75                 total_pixels = total_active_pixels + h_blank_pixels;
  76                 pixel_freq = total_pixels * h_freq / 1000.0;
  77         } else {
  78                 // pixel clock rate (MHz)
  79                 pixel_freq = ip_freq_rqd;
  80                 double ideal_h_period =
  81                         ((C_PRIME - 100.0) +
  82                          sqrt(((100.0 - C_PRIME) * (100.0 - C_PRIME) +
  83                                (0.4 * M_PRIME * (total_active_pixels + hor_margin * 2) /
  84                                 pixel_freq)))) / 2.0 / M_PRIME * 1000.0;
  85                 double ideal_duty_cycle = C_PRIME - (M_PRIME * ideal_h_period) / 1000.0;
  86                 h_blank_pixels = round(total_active_pixels * ideal_duty_cycle /
  87                                        (100.0 - ideal_duty_cycle) /
  88                                        (2 * CELL_GRAN)) * 2 * CELL_GRAN;
  89                 total_pixels = total_active_pixels + h_blank_pixels;
  90                 double h_freq = pixel_freq / total_pixels * 1000.0;
  91                 v_sync_bp = round(GTF_MIN_VSYNC_BP * h_freq / 1000.0);
  92         }
  93
  94         double v_back_porch = v_sync_bp - GTF_V_SYNC_RQD;
  95
  96         t.vbp = v_back_porch;
  97         t.vsync = GTF_V_SYNC_RQD;
  98         t.vfp = GTF_MIN_PORCH;
  99         t.pixclk_khz = round(1000.0 * pixel_freq);
 100         t.hsync = round(GTF_H_SYNC_PERC / 100.0 * total_pixels / CELL_GRAN) * CELL_GRAN;
 101         t.hfp = (h_blank_pixels / 2.0) - t.hsync;
 102         t.hbp = t.hfp + t.hsync;
 103         t.hborder = hor_margin;
 104         t.vborder = vert_margin;
 105         t.pos_pol_hsync = secondary;
 106         t.pos_pol_vsync = !secondary;
 107         t.rb = secondary ? RB_GTF : RB_NONE;
 108         return t;
 109 }
 110
 111 void edid_state::edid_gtf_mode(unsigned refresh, struct timings &t)
 112 {
 113         unsigned hratio = t.hratio;
 114         unsigned vratio = t.vratio;
 115         t = calc_gtf_mode(t.hact, t.vact, refresh, t.interlaced);
 116         t.hratio = hratio;
 117         t.vratio = vratio;
 118 }
 119
 120 #define CVT_MIN_VSYNC_BP 550.0
 121 #define CVT_MIN_V_PORCH 3
 122 #define CVT_MIN_V_BPORCH 6
 123 #define CVT_C_PRIME 30.0
 124 #define CVT_M_PRIME 300.0
 125 #define CVT_RB_MIN_VBLANK 460.0
 126
 127 // If rb == RB_CVT_V2, then alt means video-optimized (i.e. 59.94 instead of 60 Hz, etc.).
 128 // If rb == RB_CVT_V3, then alt means that rb_h_blank is 160 instead of 80.
 129 // Note: for RB_CVT_V3 this calculation is slightly different, but
 130 // since CVT 1.3 is not yet public, I cannot update the calculation yet. For now
 131 // it will follow V2. So RBv3 timings will be off for now.
 132 timings edid_state::calc_cvt_mode(unsigned h_pixels, unsigned v_lines,
 133                                   double ip_freq_rqd, unsigned rb, bool int_rqd,
 134                                   bool margins_rqd, bool alt)
 135 {
 136         timings t = {};
 137
 138         t.hact = h_pixels;
 139         t.vact = v_lines;
 140         t.interlaced = int_rqd;
 141
 142         double cell_gran = rb == RB_CVT_V2 ? 1 : CELL_GRAN;
 143         double h_pixels_rnd = floor(h_pixels / cell_gran) * cell_gran;
 144         double v_lines_rnd = int_rqd ? floor(v_lines / 2.0) : v_lines;
 145         unsigned hor_margin = margins_rqd ?
 146                 floor((h_pixels_rnd * MARGIN_PERC / 100.0) / cell_gran) * cell_gran : 0;
 147         unsigned vert_margin = margins_rqd ? floor(MARGIN_PERC / 100.0 * v_lines_rnd) : 0;
 148         double interlace = int_rqd ? 0.5 : 0;
 149         double total_active_pixels = h_pixels_rnd + hor_margin * 2;
 150         double v_field_rate_rqd = int_rqd ? ip_freq_rqd * 2 : ip_freq_rqd;
 151         double clock_step = rb == RB_CVT_V2 ? 0.001 : 0.25;
 152         double h_blank = (rb == RB_CVT_V1 || (rb == RB_CVT_V3 && alt)) ? 160 : 80;
 153         double rb_v_fporch = rb == RB_CVT_V1 ? 3 : 1;
 154         double refresh_multiplier = (rb == RB_CVT_V2 && alt) ? 1000.0 / 1001.0 : 1;
 155         double h_sync = 32;
 156
 157         double v_sync;
 158         double pixel_freq;
 159         double v_blank;
 160         double v_sync_bp;
 161
 162         /* Determine VSync Width from aspect ratio */
 163         if ((t.vact * 4 / 3) == t.hact)
 164                 v_sync = 4;
 165         else if ((t.vact * 16 / 9) == t.hact)
 166                 v_sync = 5;
 167         else if ((t.vact * 16 / 10) == t.hact)
 168                 v_sync = 6;
 169         else if (!(t.vact % 4) && ((t.vact * 5 / 4) == t.hact))
 170                 v_sync = 7;
 171         else if ((t.vact * 15 / 9) == t.hact)
 172                 v_sync = 7;
 173         else                        /* Custom */
 174                 v_sync = 10;
 175
 176         if (rb >= RB_CVT_V2)
 177                 v_sync = 8;
 178
 179         if (rb == RB_NONE) {
 180                 double h_period_est = ((1.0 / v_field_rate_rqd) - CVT_MIN_VSYNC_BP / 1000000.0) /
 181                         (v_lines_rnd + vert_margin * 2 + CVT_MIN_V_PORCH + interlace) * 1000000.0;
 182                 v_sync_bp = floor(CVT_MIN_VSYNC_BP / h_period_est) + 1;
 183                 if (v_sync_bp < v_sync + CVT_MIN_V_BPORCH)
 184                         v_sync_bp = v_sync + CVT_MIN_V_BPORCH;
 185                 v_blank = v_sync_bp + CVT_MIN_V_PORCH;
 186                 double ideal_duty_cycle = CVT_C_PRIME - (CVT_M_PRIME * h_period_est / 1000.0);
 187                 if (ideal_duty_cycle < 20)
 188                         ideal_duty_cycle = 20;
 189                 h_blank = floor(total_active_pixels * ideal_duty_cycle /
 190                                 (100.0 - ideal_duty_cycle) /
 191                                 (2 * CELL_GRAN)) * 2 * CELL_GRAN;
 192                 double total_pixels = total_active_pixels + h_blank;
 193                 h_sync = floor(total_pixels * 0.08 / CELL_GRAN) * CELL_GRAN;
 194                 pixel_freq = floor((total_pixels / h_period_est) / clock_step) * clock_step;
 195         } else {
 196                 double h_period_est = ((1000000.0 / v_field_rate_rqd) - CVT_RB_MIN_VBLANK) /
 197                                         (v_lines_rnd + vert_margin * 2);
 198                 double vbi_lines = floor(CVT_RB_MIN_VBLANK / h_period_est) + 1;
 199                 double rb_min_vbi = rb_v_fporch + v_sync + CVT_MIN_V_BPORCH;
 200                 v_blank = vbi_lines < rb_min_vbi ? rb_min_vbi : vbi_lines;
 201                 double total_v_lines = v_blank + v_lines_rnd + vert_margin * 2 + interlace;
 202                 if (rb == RB_CVT_V1)
 203                         v_sync_bp = v_blank - rb_v_fporch;
 204                 else
 205                         v_sync_bp = v_sync + CVT_MIN_V_BPORCH;
 206                 double total_pixels = h_blank + total_active_pixels;
 207                 pixel_freq = floor((v_field_rate_rqd * total_v_lines * total_pixels / 1000000.0 *
 208                                     refresh_multiplier) / clock_step) * clock_step;
 209         }
 210
 211         t.vbp = v_sync_bp - v_sync;
 212         t.vsync = v_sync;
 213         t.vfp = v_blank - t.vbp - t.vsync;
 214         t.pixclk_khz = round(1000.0 * pixel_freq);
 215         t.hsync = h_sync;
 216         t.hfp = (h_blank / 2.0) - t.hsync;
 217         t.hbp = t.hfp + t.hsync;
 218         t.hborder = hor_margin;
 219         t.vborder = vert_margin;
 220         t.rb = rb;
 221         if (alt && (rb == RB_CVT_V2 || rb == RB_CVT_V3))
 222                 t.rb |= RB_ALT;
 223         t.pos_pol_hsync = t.rb;
 224         t.pos_pol_vsync = !t.rb;
 225         calc_ratio(&t);
 226         return t;
 227 }
 228
 229 void edid_state::edid_cvt_mode(unsigned refresh, struct timings &t)
 230 {
 231         unsigned hratio = t.hratio;
 232         unsigned vratio = t.vratio;
 233
 234         t = calc_cvt_mode(t.hact, t.vact, refresh, t.rb & ~RB_ALT, t.interlaced,
 235                           false, t.rb & RB_ALT);
 236         t.hratio = hratio;
 237         t.vratio = vratio;
 238 }