drivers/media/v4l2-core/v4l2-dv-timings.c

   1 /*
   2  * v4l2-dv-timings - dv-timings helper functions
   3  *
   4  * Copyright 2013 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   5  *
   6  * This program is free software; you may redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  11  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  12  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  13  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  14  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  15  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  16  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  17  * SOFTWARE.
  18  *
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/types.h>
  23 #include <linux/kernel.h>
  24 #include <linux/errno.h>
  25 #include <linux/videodev2.h>
  26 #include <linux/v4l2-dv-timings.h>
  27 #include <media/v4l2-dv-timings.h>
  28
  29 const struct v4l2_dv_timings v4l2_dv_timings_presets[] = {
  30         V4L2_DV_BT_CEA_640X480P59_94,
  31         V4L2_DV_BT_CEA_720X480I59_94,
  32         V4L2_DV_BT_CEA_720X480P59_94,
  33         V4L2_DV_BT_CEA_720X576I50,
  34         V4L2_DV_BT_CEA_720X576P50,
  35         V4L2_DV_BT_CEA_1280X720P24,
  36         V4L2_DV_BT_CEA_1280X720P25,
  37         V4L2_DV_BT_CEA_1280X720P30,
  38         V4L2_DV_BT_CEA_1280X720P50,
  39         V4L2_DV_BT_CEA_1280X720P60,
  40         V4L2_DV_BT_CEA_1920X1080P24,
  41         V4L2_DV_BT_CEA_1920X1080P25,
  42         V4L2_DV_BT_CEA_1920X1080P30,
  43         V4L2_DV_BT_CEA_1920X1080I50,
  44         V4L2_DV_BT_CEA_1920X1080P50,
  45         V4L2_DV_BT_CEA_1920X1080I60,
  46         V4L2_DV_BT_CEA_1920X1080P60,
  47         V4L2_DV_BT_DMT_640X350P85,
  48         V4L2_DV_BT_DMT_640X400P85,
  49         V4L2_DV_BT_DMT_720X400P85,
  50         V4L2_DV_BT_DMT_640X480P72,
  51         V4L2_DV_BT_DMT_640X480P75,
  52         V4L2_DV_BT_DMT_640X480P85,
  53         V4L2_DV_BT_DMT_800X600P56,
  54         V4L2_DV_BT_DMT_800X600P60,
  55         V4L2_DV_BT_DMT_800X600P72,
  56         V4L2_DV_BT_DMT_800X600P75,
  57         V4L2_DV_BT_DMT_800X600P85,
  58         V4L2_DV_BT_DMT_800X600P120_RB,
  59         V4L2_DV_BT_DMT_848X480P60,
  60         V4L2_DV_BT_DMT_1024X768I43,
  61         V4L2_DV_BT_DMT_1024X768P60,
  62         V4L2_DV_BT_DMT_1024X768P70,
  63         V4L2_DV_BT_DMT_1024X768P75,
  64         V4L2_DV_BT_DMT_1024X768P85,
  65         V4L2_DV_BT_DMT_1024X768P120_RB,
  66         V4L2_DV_BT_DMT_1152X864P75,
  67         V4L2_DV_BT_DMT_1280X768P60_RB,
  68         V4L2_DV_BT_DMT_1280X768P60,
  69         V4L2_DV_BT_DMT_1280X768P75,
  70         V4L2_DV_BT_DMT_1280X768P85,
  71         V4L2_DV_BT_DMT_1280X768P120_RB,
  72         V4L2_DV_BT_DMT_1280X800P60_RB,
  73         V4L2_DV_BT_DMT_1280X800P60,
  74         V4L2_DV_BT_DMT_1280X800P75,
  75         V4L2_DV_BT_DMT_1280X800P85,
  76         V4L2_DV_BT_DMT_1280X800P120_RB,
  77         V4L2_DV_BT_DMT_1280X960P60,
  78         V4L2_DV_BT_DMT_1280X960P85,
  79         V4L2_DV_BT_DMT_1280X960P120_RB,
  80         V4L2_DV_BT_DMT_1280X1024P60,
  81         V4L2_DV_BT_DMT_1280X1024P75,
  82         V4L2_DV_BT_DMT_1280X1024P85,
  83         V4L2_DV_BT_DMT_1280X1024P120_RB,
  84         V4L2_DV_BT_DMT_1360X768P60,
  85         V4L2_DV_BT_DMT_1360X768P120_RB,
  86         V4L2_DV_BT_DMT_1366X768P60,
  87         V4L2_DV_BT_DMT_1366X768P60_RB,
  88         V4L2_DV_BT_DMT_1400X1050P60_RB,
  89         V4L2_DV_BT_DMT_1400X1050P60,
  90         V4L2_DV_BT_DMT_1400X1050P75,
  91         V4L2_DV_BT_DMT_1400X1050P85,
  92         V4L2_DV_BT_DMT_1400X1050P120_RB,
  93         V4L2_DV_BT_DMT_1440X900P60_RB,
  94         V4L2_DV_BT_DMT_1440X900P60,
  95         V4L2_DV_BT_DMT_1440X900P75,
  96         V4L2_DV_BT_DMT_1440X900P85,
  97         V4L2_DV_BT_DMT_1440X900P120_RB,
  98         V4L2_DV_BT_DMT_1600X900P60_RB,
  99         V4L2_DV_BT_DMT_1600X1200P60,
 100         V4L2_DV_BT_DMT_1600X1200P65,
 101         V4L2_DV_BT_DMT_1600X1200P70,
 102         V4L2_DV_BT_DMT_1600X1200P75,
 103         V4L2_DV_BT_DMT_1600X1200P85,
 104         V4L2_DV_BT_DMT_1600X1200P120_RB,
 105         V4L2_DV_BT_DMT_1680X1050P60_RB,
 106         V4L2_DV_BT_DMT_1680X1050P60,
 107         V4L2_DV_BT_DMT_1680X1050P75,
 108         V4L2_DV_BT_DMT_1680X1050P85,
 109         V4L2_DV_BT_DMT_1680X1050P120_RB,
 110         V4L2_DV_BT_DMT_1792X1344P60,
 111         V4L2_DV_BT_DMT_1792X1344P75,
 112         V4L2_DV_BT_DMT_1792X1344P120_RB,
 113         V4L2_DV_BT_DMT_1856X1392P60,
 114         V4L2_DV_BT_DMT_1856X1392P75,
 115         V4L2_DV_BT_DMT_1856X1392P120_RB,
 116         V4L2_DV_BT_DMT_1920X1200P60_RB,
 117         V4L2_DV_BT_DMT_1920X1200P60,
 118         V4L2_DV_BT_DMT_1920X1200P75,
 119         V4L2_DV_BT_DMT_1920X1200P85,
 120         V4L2_DV_BT_DMT_1920X1200P120_RB,
 121         V4L2_DV_BT_DMT_1920X1440P60,
 122         V4L2_DV_BT_DMT_1920X1440P75,
 123         V4L2_DV_BT_DMT_1920X1440P120_RB,
 124         V4L2_DV_BT_DMT_2048X1152P60_RB,
 125         V4L2_DV_BT_DMT_2560X1600P60_RB,
 126         V4L2_DV_BT_DMT_2560X1600P60,
 127         V4L2_DV_BT_DMT_2560X1600P75,
 128         V4L2_DV_BT_DMT_2560X1600P85,
 129         V4L2_DV_BT_DMT_2560X1600P120_RB,
 130         { }
 131 };
 132 EXPORT_SYMBOL_GPL(v4l2_dv_timings_presets);
 133
 134 bool v4l2_dv_valid_timings(const struct v4l2_dv_timings *t,
 135                            const struct v4l2_dv_timings_cap *dvcap)
 136 {
 137         const struct v4l2_bt_timings *bt = &t->bt;
 138         const struct v4l2_bt_timings_cap *cap = &dvcap->bt;
 139         u32 caps = cap->capabilities;
 140
 141         if (t->type != V4L2_DV_BT_656_1120)
 142                 return false;
 143         if (t->type != dvcap->type ||
 144             bt->height < cap->min_height ||
 145             bt->height > cap->max_height ||
 146             bt->width < cap->min_width ||
 147             bt->width > cap->max_width ||
 148             bt->pixelclock < cap->min_pixelclock ||
 149             bt->pixelclock > cap->max_pixelclock ||
 150             (cap->standards && !(bt->standards & cap->standards)) ||
 151             (bt->interlaced && !(caps & V4L2_DV_BT_CAP_INTERLACED)) ||
 152             (!bt->interlaced && !(caps & V4L2_DV_BT_CAP_PROGRESSIVE)))
 153                 return false;
 154         return true;
 155 }
 156 EXPORT_SYMBOL_GPL(v4l2_dv_valid_timings);
 157
 158 int v4l2_enum_dv_timings_cap(struct v4l2_enum_dv_timings *t,
 159                              const struct v4l2_dv_timings_cap *cap)
 160 {
 161         u32 i, idx;
 162
 163         memset(t->reserved, 0, sizeof(t->reserved));
 164         for (i = idx = 0; v4l2_dv_timings_presets[i].bt.width; i++) {
 165                 if (v4l2_dv_valid_timings(v4l2_dv_timings_presets + i, cap) &&
 166                     idx++ == t->index) {
 167                         t->timings = v4l2_dv_timings_presets[i];
 168                         return 0;
 169                 }
 170         }
 171         return -EINVAL;
 172 }
 173 EXPORT_SYMBOL_GPL(v4l2_enum_dv_timings_cap);
 174
 175 bool v4l2_find_dv_timings_cap(struct v4l2_dv_timings *t,
 176                               const struct v4l2_dv_timings_cap *cap,
 177                               unsigned pclock_delta)
 178 {
 179         int i;
 180
 181         if (!v4l2_dv_valid_timings(t, cap))
 182                 return false;
 183
 184         for (i = 0; i < v4l2_dv_timings_presets[i].bt.width; i++) {
 185                 if (v4l2_dv_valid_timings(v4l2_dv_timings_presets + i, cap) &&
 186                     v4l2_match_dv_timings(t, v4l2_dv_timings_presets + i, pclock_delta)) {
 187                         *t = v4l2_dv_timings_presets[i];
 188                         return true;
 189                 }
 190         }
 191         return false;
 192 }
 193 EXPORT_SYMBOL_GPL(v4l2_find_dv_timings_cap);
 194
 195 /**
 196  * v4l2_match_dv_timings - check if two timings match
 197  * @t1 - compare this v4l2_dv_timings struct...
 198  * @t2 - with this struct.
 199  * @pclock_delta - the allowed pixelclock deviation.
 200  *
 201  * Compare t1 with t2 with a given margin of error for the pixelclock.
 202  */
 203 bool v4l2_match_dv_timings(const struct v4l2_dv_timings *t1,
 204                            const struct v4l2_dv_timings *t2,
 205                            unsigned pclock_delta)
 206 {
 207         if (t1->type != t2->type || t1->type != V4L2_DV_BT_656_1120)
 208                 return false;
 209         if (t1->bt.width == t2->bt.width &&
 210             t1->bt.height == t2->bt.height &&
 211             t1->bt.interlaced == t2->bt.interlaced &&
 212             t1->bt.polarities == t2->bt.polarities &&
 213             t1->bt.pixelclock >= t2->bt.pixelclock - pclock_delta &&
 214             t1->bt.pixelclock <= t2->bt.pixelclock + pclock_delta &&
 215             t1->bt.hfrontporch == t2->bt.hfrontporch &&
 216             t1->bt.vfrontporch == t2->bt.vfrontporch &&
 217             t1->bt.vsync == t2->bt.vsync &&
 218             t1->bt.vbackporch == t2->bt.vbackporch &&
 219             (!t1->bt.interlaced ||
 220                 (t1->bt.il_vfrontporch == t2->bt.il_vfrontporch &&
 221                  t1->bt.il_vsync == t2->bt.il_vsync &&
 222                  t1->bt.il_vbackporch == t2->bt.il_vbackporch)))
 223                 return true;
 224         return false;
 225 }
 226 EXPORT_SYMBOL_GPL(v4l2_match_dv_timings);
 227
 228 void v4l2_print_dv_timings(const char *dev_prefix, const char *prefix,
 229                            const struct v4l2_dv_timings *t, bool detailed)
 230 {
 231         const struct v4l2_bt_timings *bt = &t->bt;
 232         u32 htot, vtot;
 233
 234         if (t->type != V4L2_DV_BT_656_1120)
 235                 return;
 236
 237         htot = V4L2_DV_BT_FRAME_WIDTH(bt);
 238         vtot = V4L2_DV_BT_FRAME_HEIGHT(bt);
 239
 240         if (prefix == NULL)
 241                 prefix = "";
 242
 243         pr_info("%s: %s%ux%u%s%u (%ux%u)\n", dev_prefix, prefix,
 244                 bt->width, bt->height, bt->interlaced ? "i" : "p",
 245                 (htot * vtot) > 0 ? ((u32)bt->pixelclock / (htot * vtot)) : 0,
 246                 htot, vtot);
 247
 248         if (!detailed)
 249                 return;
 250
 251         pr_info("%s: horizontal: fp = %u, %ssync = %u, bp = %u\n",
 252                         dev_prefix, bt->hfrontporch,
 253                         (bt->polarities & V4L2_DV_HSYNC_POS_POL) ? "+" : "-",
 254                         bt->hsync, bt->hbackporch);
 255         pr_info("%s: vertical: fp = %u, %ssync = %u, bp = %u\n",
 256                         dev_prefix, bt->vfrontporch,
 257                         (bt->polarities & V4L2_DV_VSYNC_POS_POL) ? "+" : "-",
 258                         bt->vsync, bt->vbackporch);
 259         pr_info("%s: pixelclock: %llu\n", dev_prefix, bt->pixelclock);
 260         pr_info("%s: flags (0x%x):%s%s%s%s\n", dev_prefix, bt->flags,
 261                         (bt->flags & V4L2_DV_FL_REDUCED_BLANKING) ?
 262                         " REDUCED_BLANKING" : "",
 263                         (bt->flags & V4L2_DV_FL_CAN_REDUCE_FPS) ?
 264                         " CAN_REDUCE_FPS" : "",
 265                         (bt->flags & V4L2_DV_FL_REDUCED_FPS) ?
 266                         " REDUCED_FPS" : "",
 267                         (bt->flags & V4L2_DV_FL_HALF_LINE) ?
 268                         " HALF_LINE" : "");
 269         pr_info("%s: standards (0x%x):%s%s%s%s\n", dev_prefix, bt->standards,
 270                         (bt->standards & V4L2_DV_BT_STD_CEA861) ?  " CEA" : "",
 271                         (bt->standards & V4L2_DV_BT_STD_DMT) ?  " DMT" : "",
 272                         (bt->standards & V4L2_DV_BT_STD_CVT) ?  " CVT" : "",
 273                         (bt->standards & V4L2_DV_BT_STD_GTF) ?  " GTF" : "");
 274 }
 275 EXPORT_SYMBOL_GPL(v4l2_print_dv_timings);
 276
 277 /*
 278  * CVT defines
 279  * Based on Coordinated Video Timings Standard
 280  * version 1.1 September 10, 2003
 281  */
 282
 283 #define CVT_PXL_CLK_GRAN        250000  /* pixel clock granularity */
 284
 285 /* Normal blanking */
 286 #define CVT_MIN_V_BPORCH        7       /* lines */
 287 #define CVT_MIN_V_PORCH_RND     3       /* lines */
 288 #define CVT_MIN_VSYNC_BP        550     /* min time of vsync + back porch (us) */
 289
 290 /* Normal blanking for CVT uses GTF to calculate horizontal blanking */
 291 #define CVT_CELL_GRAN           8       /* character cell granularity */
 292 #define CVT_M                   600     /* blanking formula gradient */
 293 #define CVT_C                   40      /* blanking formula offset */
 294 #define CVT_K                   128     /* blanking formula scaling factor */
 295 #define CVT_J                   20      /* blanking formula scaling factor */
 296 #define CVT_C_PRIME (((CVT_C - CVT_J) * CVT_K / 256) + CVT_J)
 297 #define CVT_M_PRIME (CVT_K * CVT_M / 256)
 298
 299 /* Reduced Blanking */
 300 #define CVT_RB_MIN_V_BPORCH    7       /* lines  */
 301 #define CVT_RB_V_FPORCH        3       /* lines  */
 302 #define CVT_RB_MIN_V_BLANK   460     /* us     */
 303 #define CVT_RB_H_SYNC         32       /* pixels */
 304 #define CVT_RB_H_BPORCH       80       /* pixels */
 305 #define CVT_RB_H_BLANK       160       /* pixels */
 306
 307 /** v4l2_detect_cvt - detect if the given timings follow the CVT standard
 308  * @frame_height - the total height of the frame (including blanking) in lines.
 309  * @hfreq - the horizontal frequency in Hz.
 310  * @vsync - the height of the vertical sync in lines.
 311  * @polarities - the horizontal and vertical polarities (same as struct
 312  *              v4l2_bt_timings polarities).
 313  * @fmt - the resulting timings.
 314  *
 315  * This function will attempt to detect if the given values correspond to a
 316  * valid CVT format. If so, then it will return true, and fmt will be filled
 317  * in with the found CVT timings.
 318  */
 319 bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
 320                 u32 polarities, struct v4l2_dv_timings *fmt)
 321 {
 322         int  v_fp, v_bp, h_fp, h_bp, hsync;
 323         int  frame_width, image_height, image_width;
 324         bool reduced_blanking;
 325         unsigned pix_clk;
 326
 327         if (vsync < 4 || vsync > 7)
 328                 return false;
 329
 330         if (polarities == V4L2_DV_VSYNC_POS_POL)
 331                 reduced_blanking = false;
 332         else if (polarities == V4L2_DV_HSYNC_POS_POL)
 333                 reduced_blanking = true;
 334         else
 335                 return false;
 336
 337         /* Vertical */
 338         if (reduced_blanking) {
 339                 v_fp = CVT_RB_V_FPORCH;
 340                 v_bp = (CVT_RB_MIN_V_BLANK * hfreq + 1999999) / 1000000;
 341                 v_bp -= vsync + v_fp;
 342
 343                 if (v_bp < CVT_RB_MIN_V_BPORCH)
 344                         v_bp = CVT_RB_MIN_V_BPORCH;
 345         } else {
 346                 v_fp = CVT_MIN_V_PORCH_RND;
 347                 v_bp = (CVT_MIN_VSYNC_BP * hfreq + 1999999) / 1000000 - vsync;
 348
 349                 if (v_bp < CVT_MIN_V_BPORCH)
 350                         v_bp = CVT_MIN_V_BPORCH;
 351         }
 352         image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;
 353
 354         /* Aspect ratio based on vsync */
 355         switch (vsync) {
 356         case 4:
 357                 image_width = (image_height * 4) / 3;
 358                 break;
 359         case 5:
 360                 image_width = (image_height * 16) / 9;
 361                 break;
 362         case 6:
 363                 image_width = (image_height * 16) / 10;
 364                 break;
 365         case 7:
 366                 /* special case */
 367                 if (image_height == 1024)
 368                         image_width = (image_height * 5) / 4;
 369                 else if (image_height == 768)
 370                         image_width = (image_height * 15) / 9;
 371                 else
 372                         return false;
 373                 break;
 374         default:
 375                 return false;
 376         }
 377
 378         image_width = image_width & ~7;
 379
 380         /* Horizontal */
 381         if (reduced_blanking) {
 382                 pix_clk = (image_width + CVT_RB_H_BLANK) * hfreq;
 383                 pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;
 384
 385                 h_bp = CVT_RB_H_BPORCH;
 386                 hsync = CVT_RB_H_SYNC;
 387                 h_fp = CVT_RB_H_BLANK - h_bp - hsync;
 388
 389                 frame_width = image_width + CVT_RB_H_BLANK;
 390         } else {
 391                 unsigned ideal_duty_cycle_per_myriad =
 392                         100 * CVT_C_PRIME - (CVT_M_PRIME * 100000) / hfreq;
 393                 int h_blank;
 394
 395                 if (ideal_duty_cycle_per_myriad < 2000)
 396                         ideal_duty_cycle_per_myriad = 2000;
 397
 398                 h_blank = image_width * ideal_duty_cycle_per_myriad /
 399                                         (10000 - ideal_duty_cycle_per_myriad);
 400                 h_blank = (h_blank / (2 * CVT_CELL_GRAN)) * 2 * CVT_CELL_GRAN;
 401
 402                 pix_clk = (image_width + h_blank) * hfreq;
 403                 pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;
 404
 405                 h_bp = h_blank / 2;
 406                 frame_width = image_width + h_blank;
 407
 408                 hsync = (frame_width * 8 + 50) / 100;
 409                 hsync = hsync - hsync % CVT_CELL_GRAN;
 410                 h_fp = h_blank - hsync - h_bp;
 411         }
 412
 413         fmt->type = V4L2_DV_BT_656_1120;
 414         fmt->bt.polarities = polarities;
 415         fmt->bt.width = image_width;
 416         fmt->bt.height = image_height;
 417         fmt->bt.hfrontporch = h_fp;
 418         fmt->bt.vfrontporch = v_fp;
 419         fmt->bt.hsync = hsync;
 420         fmt->bt.vsync = vsync;
 421         fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
 422         fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
 423         fmt->bt.pixelclock = pix_clk;
 424         fmt->bt.standards = V4L2_DV_BT_STD_CVT;
 425         if (reduced_blanking)
 426                 fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
 427         return true;
 428 }
 429 EXPORT_SYMBOL_GPL(v4l2_detect_cvt);
 430
 431 /*
 432  * GTF defines
 433  * Based on Generalized Timing Formula Standard
 434  * Version 1.1 September 2, 1999
 435  */
 436
 437 #define GTF_PXL_CLK_GRAN        250000  /* pixel clock granularity */
 438
 439 #define GTF_MIN_VSYNC_BP        550     /* min time of vsync + back porch (us) */
 440 #define GTF_V_FP                1       /* vertical front porch (lines) */
 441 #define GTF_CELL_GRAN           8       /* character cell granularity */
 442
 443 /* Default */
 444 #define GTF_D_M                 600     /* blanking formula gradient */
 445 #define GTF_D_C                 40      /* blanking formula offset */
 446 #define GTF_D_K                 128     /* blanking formula scaling factor */
 447 #define GTF_D_J                 20      /* blanking formula scaling factor */
 448 #define GTF_D_C_PRIME ((((GTF_D_C - GTF_D_J) * GTF_D_K) / 256) + GTF_D_J)
 449 #define GTF_D_M_PRIME ((GTF_D_K * GTF_D_M) / 256)
 450
 451 /* Secondary */
 452 #define GTF_S_M                 3600    /* blanking formula gradient */
 453 #define GTF_S_C                 40      /* blanking formula offset */
 454 #define GTF_S_K                 128     /* blanking formula scaling factor */
 455 #define GTF_S_J                 35      /* blanking formula scaling factor */
 456 #define GTF_S_C_PRIME ((((GTF_S_C - GTF_S_J) * GTF_S_K) / 256) + GTF_S_J)
 457 #define GTF_S_M_PRIME ((GTF_S_K * GTF_S_M) / 256)
 458
 459 /** v4l2_detect_gtf - detect if the given timings follow the GTF standard
 460  * @frame_height - the total height of the frame (including blanking) in lines.
 461  * @hfreq - the horizontal frequency in Hz.
 462  * @vsync - the height of the vertical sync in lines.
 463  * @polarities - the horizontal and vertical polarities (same as struct
 464  *              v4l2_bt_timings polarities).
 465  * @aspect - preferred aspect ratio. GTF has no method of determining the
 466  *              aspect ratio in order to derive the image width from the
 467  *              image height, so it has to be passed explicitly. Usually
 468  *              the native screen aspect ratio is used for this. If it
 469  *              is not filled in correctly, then 16:9 will be assumed.
 470  * @fmt - the resulting timings.
 471  *
 472  * This function will attempt to detect if the given values correspond to a
 473  * valid GTF format. If so, then it will return true, and fmt will be filled
 474  * in with the found GTF timings.
 475  */
 476 bool v4l2_detect_gtf(unsigned frame_height,
 477                 unsigned hfreq,
 478                 unsigned vsync,
 479                 u32 polarities,
 480                 struct v4l2_fract aspect,
 481                 struct v4l2_dv_timings *fmt)
 482 {
 483         int pix_clk;
 484         int  v_fp, v_bp, h_fp, hsync;
 485         int frame_width, image_height, image_width;
 486         bool default_gtf;
 487         int h_blank;
 488
 489         if (vsync != 3)
 490                 return false;
 491
 492         if (polarities == V4L2_DV_VSYNC_POS_POL)
 493                 default_gtf = true;
 494         else if (polarities == V4L2_DV_HSYNC_POS_POL)
 495                 default_gtf = false;
 496         else
 497                 return false;
 498
 499         /* Vertical */
 500         v_fp = GTF_V_FP;
 501         v_bp = (GTF_MIN_VSYNC_BP * hfreq + 999999) / 1000000 - vsync;
 502         image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;
 503
 504         if (aspect.numerator == 0 || aspect.denominator == 0) {
 505                 aspect.numerator = 16;
 506                 aspect.denominator = 9;
 507         }
 508         image_width = ((image_height * aspect.numerator) / aspect.denominator);
 509
 510         /* Horizontal */
 511         if (default_gtf)
 512                 h_blank = ((image_width * GTF_D_C_PRIME * hfreq) -
 513                                         (image_width * GTF_D_M_PRIME * 1000) +
 514                         (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000) / 2) /
 515                         (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000);
 516         else
 517                 h_blank = ((image_width * GTF_S_C_PRIME * hfreq) -
 518                                         (image_width * GTF_S_M_PRIME * 1000) +
 519                         (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000) / 2) /
 520                         (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000);
 521
 522         h_blank = h_blank - h_blank % (2 * GTF_CELL_GRAN);
 523         frame_width = image_width + h_blank;
 524
 525         pix_clk = (image_width + h_blank) * hfreq;
 526         pix_clk = pix_clk / GTF_PXL_CLK_GRAN * GTF_PXL_CLK_GRAN;
 527
 528         hsync = (frame_width * 8 + 50) / 100;
 529         hsync = hsync - hsync % GTF_CELL_GRAN;
 530
 531         h_fp = h_blank / 2 - hsync;
 532
 533         fmt->type = V4L2_DV_BT_656_1120;
 534         fmt->bt.polarities = polarities;
 535         fmt->bt.width = image_width;
 536         fmt->bt.height = image_height;
 537         fmt->bt.hfrontporch = h_fp;
 538         fmt->bt.vfrontporch = v_fp;
 539         fmt->bt.hsync = hsync;
 540         fmt->bt.vsync = vsync;
 541         fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
 542         fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
 543         fmt->bt.pixelclock = pix_clk;
 544         fmt->bt.standards = V4L2_DV_BT_STD_GTF;
 545         if (!default_gtf)
 546                 fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
 547         return true;
 548 }
 549 EXPORT_SYMBOL_GPL(v4l2_detect_gtf);
 550
 551 /** v4l2_calc_aspect_ratio - calculate the aspect ratio based on bytes
 552  *      0x15 and 0x16 from the EDID.
 553  * @hor_landscape - byte 0x15 from the EDID.
 554  * @vert_portrait - byte 0x16 from the EDID.
 555  *
 556  * Determines the aspect ratio from the EDID.
 557  * See VESA Enhanced EDID standard, release A, rev 2, section 3.6.2:
 558  * "Horizontal and Vertical Screen Size or Aspect Ratio"
 559  */
 560 struct v4l2_fract v4l2_calc_aspect_ratio(u8 hor_landscape, u8 vert_portrait)
 561 {
 562         struct v4l2_fract aspect = { 16, 9 };
 563         u32 tmp;
 564         u8 ratio;
 565
 566         /* Nothing filled in, fallback to 16:9 */
 567         if (!hor_landscape && !vert_portrait)
 568                 return aspect;
 569         /* Both filled in, so they are interpreted as the screen size in cm */
 570         if (hor_landscape && vert_portrait) {
 571                 aspect.numerator = hor_landscape;
 572                 aspect.denominator = vert_portrait;
 573                 return aspect;
 574         }
 575         /* Only one is filled in, so interpret them as a ratio:
 576            (val + 99) / 100 */
 577         ratio = hor_landscape | vert_portrait;
 578         /* Change some rounded values into the exact aspect ratio */
 579         if (ratio == 79) {
 580                 aspect.numerator = 16;
 581                 aspect.denominator = 9;
 582         } else if (ratio == 34) {
 583                 aspect.numerator = 4;
 584                 aspect.numerator = 3;
 585         } else if (ratio == 68) {
 586                 aspect.numerator = 15;
 587                 aspect.numerator = 9;
 588         } else {
 589                 aspect.numerator = hor_landscape + 99;
 590                 aspect.denominator = 100;
 591         }
 592         if (hor_landscape)
 593                 return aspect;
 594         /* The aspect ratio is for portrait, so swap numerator and denominator */
 595         tmp = aspect.denominator;
 596         aspect.denominator = aspect.numerator;
 597         aspect.numerator = tmp;
 598         return aspect;
 599 }
 600 EXPORT_SYMBOL_GPL(v4l2_calc_aspect_ratio);