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 /* Minimum vertical backporch for CVT and CVT RBv1 */
 123 #define CVT_MIN_V_BPORCH 7
 124 /* Fixed vertical backporch for CVT RBv2 and RBv3 */
 125 #define CVT_FIXED_V_BPORCH 6
 126 #define CVT_C_PRIME 30.0
 127 #define CVT_M_PRIME 300.0
 128 #define CVT_RB_MIN_VBLANK 460.0
 129
 130 // If rb == RB_CVT_V2, then alt means video-optimized (i.e. 59.94 instead of 60 Hz, etc.).
 131 // If rb == RB_CVT_V3, then alt means that rb_h_blank is 160 instead of 80.
 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, unsigned rb_h_blank,
 135                                   unsigned rb_v_blank, bool early_vsync_rqd)
 136 {
 137         timings t = {};
 138
 139         t.hact = h_pixels;
 140         t.vact = v_lines;
 141         t.interlaced = int_rqd;
 142
 143         if (rb_v_blank < CVT_RB_MIN_VBLANK)
 144                 rb_v_blank = CVT_RB_MIN_VBLANK;
 145
 146         double cell_gran = rb == RB_CVT_V2 ? 1 : CELL_GRAN;
 147         double h_pixels_rnd = floor(h_pixels / cell_gran) * cell_gran;
 148         double v_lines_rnd = int_rqd ? floor(v_lines / 2.0) : v_lines;
 149         unsigned hor_margin = margins_rqd ?
 150                 floor((h_pixels_rnd * MARGIN_PERC / 100.0) / cell_gran) * cell_gran : 0;
 151         unsigned vert_margin = margins_rqd ? floor(MARGIN_PERC / 100.0 * v_lines_rnd) : 0;
 152         double interlace = int_rqd ? 0.5 : 0;
 153         double total_active_pixels = h_pixels_rnd + hor_margin * 2;
 154         double v_field_rate_rqd = int_rqd ? ip_freq_rqd * 2 : ip_freq_rqd;
 155         double clock_step = rb >= RB_CVT_V2 ? 0.001 : 0.25;
 156         double h_blank = (rb == RB_CVT_V1 || (rb == RB_CVT_V3 && alt)) ? 160 : 80;
 157         double rb_v_fporch = rb == RB_CVT_V1 ? 3 : 1;
 158         double refresh_multiplier = (rb == RB_CVT_V2 && alt) ? 1000.0 / 1001.0 : 1;
 159         double rb_min_vblank = rb == RB_CVT_V3 ? rb_v_blank : CVT_RB_MIN_VBLANK;
 160         double h_sync = 32;
 161
 162         double v_sync;
 163         double pixel_freq;
 164         double v_blank;
 165         double v_sync_bp;
 166
 167         if (rb == RB_CVT_V3 && rb_h_blank) {
 168                 h_blank = rb_h_blank & ~7;
 169                 if (h_blank < 80)
 170                         h_blank = 80;
 171                 else if (h_blank > 200)
 172                         h_blank = 200;
 173         }
 174
 175         /* Determine VSync Width from aspect ratio */
 176         if ((t.vact * 4 / 3) == t.hact)
 177                 v_sync = 4;
 178         else if ((t.vact * 16 / 9) == t.hact)
 179                 v_sync = 5;
 180         else if ((t.vact * 16 / 10) == t.hact)
 181                 v_sync = 6;
 182         else if (!(t.vact % 4) && ((t.vact * 5 / 4) == t.hact))
 183                 v_sync = 7;
 184         else if ((t.vact * 15 / 9) == t.hact)
 185                 v_sync = 7;
 186         else                        /* Custom */
 187                 v_sync = 10;
 188
 189         if (rb >= RB_CVT_V2)
 190                 v_sync = 8;
 191
 192         if (rb == RB_NONE) {
 193                 double h_period_est = ((1.0 / v_field_rate_rqd) - CVT_MIN_VSYNC_BP / 1000000.0) /
 194                         (v_lines_rnd + vert_margin * 2 + CVT_MIN_V_PORCH + interlace) * 1000000.0;
 195                 v_sync_bp = floor(CVT_MIN_VSYNC_BP / h_period_est) + 1;
 196                 if (v_sync_bp < v_sync + CVT_MIN_V_BPORCH)
 197                         v_sync_bp = v_sync + CVT_MIN_V_BPORCH;
 198                 v_blank = v_sync_bp + CVT_MIN_V_PORCH;
 199                 double ideal_duty_cycle = CVT_C_PRIME - (CVT_M_PRIME * h_period_est / 1000.0);
 200                 if (ideal_duty_cycle < 20)
 201                         ideal_duty_cycle = 20;
 202                 h_blank = floor(total_active_pixels * ideal_duty_cycle /
 203                                 (100.0 - ideal_duty_cycle) /
 204                                 (2 * CELL_GRAN)) * 2 * CELL_GRAN;
 205                 double total_pixels = total_active_pixels + h_blank;
 206                 h_sync = floor(total_pixels * 0.08 / CELL_GRAN) * CELL_GRAN;
 207                 pixel_freq = floor((total_pixels / h_period_est) / clock_step) * clock_step;
 208         } else {
 209                 double h_period_est = ((1000000.0 / v_field_rate_rqd) - rb_min_vblank) /
 210                                         (v_lines_rnd + vert_margin * 2);
 211                 double vbi_lines = floor(rb_min_vblank / h_period_est) + 1;
 212                 double rb_v_bporch = (rb == RB_CVT_V1 ? CVT_MIN_V_BPORCH : CVT_FIXED_V_BPORCH);
 213                 double rb_min_vbi = rb_v_fporch + v_sync + rb_v_bporch;
 214                 v_blank = vbi_lines < rb_min_vbi ? rb_min_vbi : vbi_lines;
 215                 double total_v_lines = v_blank + v_lines_rnd + vert_margin * 2 + interlace;
 216                 if (rb == RB_CVT_V3 && early_vsync_rqd)
 217                         rb_v_bporch = floor(vbi_lines / 2.0);
 218                 if (rb == RB_CVT_V1)
 219                         v_sync_bp = v_blank - rb_v_fporch;
 220                 else
 221                         v_sync_bp = v_sync + rb_v_bporch;
 222                 double total_pixels = h_blank + total_active_pixels;
 223                 double freq = v_field_rate_rqd * total_v_lines * total_pixels * refresh_multiplier;
 224                 if (rb == RB_CVT_V3)
 225                         pixel_freq = ceil((freq / 1000000.0) / clock_step) * clock_step;
 226                 else
 227                         pixel_freq = floor((freq / 1000000.0) / clock_step) * clock_step;
 228         }
 229
 230         t.vbp = v_sync_bp - v_sync;
 231         t.vsync = v_sync;
 232         t.vfp = v_blank - t.vbp - t.vsync;
 233         t.pixclk_khz = round(1000.0 * pixel_freq);
 234         t.hsync = h_sync;
 235         if (rb >= RB_CVT_V2)
 236                 t.hfp = 8;
 237         else
 238                 t.hfp = (h_blank / 2.0) - t.hsync;
 239         t.hbp = h_blank - t.hfp - t.hsync;
 240         t.hborder = hor_margin;
 241         t.vborder = vert_margin;
 242         t.rb = rb;
 243         if (alt && (rb == RB_CVT_V2 || rb == RB_CVT_V3))
 244                 t.rb |= RB_ALT;
 245         t.pos_pol_hsync = t.rb;
 246         t.pos_pol_vsync = !t.rb;
 247         calc_ratio(&t);
 248         return t;
 249 }
 250
 251 void edid_state::edid_cvt_mode(unsigned refresh, struct timings &t, unsigned rb_h_blank,
 252                                unsigned rb_v_blank, bool early_vsync_rqd)
 253 {
 254         unsigned hratio = t.hratio;
 255         unsigned vratio = t.vratio;
 256
 257         t = calc_cvt_mode(t.hact, t.vact, refresh, t.rb & ~RB_ALT, t.interlaced,
 258                           false, t.rb & RB_ALT, rb_h_blank, rb_v_blank, early_vsync_rqd);
 259         t.hratio = hratio;
 260         t.vratio = vratio;
 261 }