kernel/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 MODULE_AUTHOR("Hans Verkuil");
  30 MODULE_DESCRIPTION("V4L2 DV Timings Helper Functions");
  31 MODULE_LICENSE("GPL");
  32
  33 const struct v4l2_dv_timings v4l2_dv_timings_presets[] = {
  34         V4L2_DV_BT_CEA_640X480P59_94,
  35         V4L2_DV_BT_CEA_720X480I59_94,
  36         V4L2_DV_BT_CEA_720X480P59_94,
  37         V4L2_DV_BT_CEA_720X576I50,
  38         V4L2_DV_BT_CEA_720X576P50,
  39         V4L2_DV_BT_CEA_1280X720P24,
  40         V4L2_DV_BT_CEA_1280X720P25,
  41         V4L2_DV_BT_CEA_1280X720P30,
  42         V4L2_DV_BT_CEA_1280X720P50,
  43         V4L2_DV_BT_CEA_1280X720P60,
  44         V4L2_DV_BT_CEA_1920X1080P24,
  45         V4L2_DV_BT_CEA_1920X1080P25,
  46         V4L2_DV_BT_CEA_1920X1080P30,
  47         V4L2_DV_BT_CEA_1920X1080I50,
  48         V4L2_DV_BT_CEA_1920X1080P50,
  49         V4L2_DV_BT_CEA_1920X1080I60,
  50         V4L2_DV_BT_CEA_1920X1080P60,
  51         V4L2_DV_BT_DMT_640X350P85,
  52         V4L2_DV_BT_DMT_640X400P85,
  53         V4L2_DV_BT_DMT_720X400P85,
  54         V4L2_DV_BT_DMT_640X480P72,
  55         V4L2_DV_BT_DMT_640X480P75,
  56         V4L2_DV_BT_DMT_640X480P85,
  57         V4L2_DV_BT_DMT_800X600P56,
  58         V4L2_DV_BT_DMT_800X600P60,
  59         V4L2_DV_BT_DMT_800X600P72,
  60         V4L2_DV_BT_DMT_800X600P75,
  61         V4L2_DV_BT_DMT_800X600P85,
  62         V4L2_DV_BT_DMT_800X600P120_RB,
  63         V4L2_DV_BT_DMT_848X480P60,
  64         V4L2_DV_BT_DMT_1024X768I43,
  65         V4L2_DV_BT_DMT_1024X768P60,
  66         V4L2_DV_BT_DMT_1024X768P70,
  67         V4L2_DV_BT_DMT_1024X768P75,
  68         V4L2_DV_BT_DMT_1024X768P85,
  69         V4L2_DV_BT_DMT_1024X768P120_RB,
  70         V4L2_DV_BT_DMT_1152X864P75,
  71         V4L2_DV_BT_DMT_1280X768P60_RB,
  72         V4L2_DV_BT_DMT_1280X768P60,
  73         V4L2_DV_BT_DMT_1280X768P75,
  74         V4L2_DV_BT_DMT_1280X768P85,
  75         V4L2_DV_BT_DMT_1280X768P120_RB,
  76         V4L2_DV_BT_DMT_1280X800P60_RB,
  77         V4L2_DV_BT_DMT_1280X800P60,
  78         V4L2_DV_BT_DMT_1280X800P75,
  79         V4L2_DV_BT_DMT_1280X800P85,
  80         V4L2_DV_BT_DMT_1280X800P120_RB,
  81         V4L2_DV_BT_DMT_1280X960P60,
  82         V4L2_DV_BT_DMT_1280X960P85,
  83         V4L2_DV_BT_DMT_1280X960P120_RB,
  84         V4L2_DV_BT_DMT_1280X1024P60,
  85         V4L2_DV_BT_DMT_1280X1024P75,
  86         V4L2_DV_BT_DMT_1280X1024P85,
  87         V4L2_DV_BT_DMT_1280X1024P120_RB,
  88         V4L2_DV_BT_DMT_1360X768P60,
  89         V4L2_DV_BT_DMT_1360X768P120_RB,
  90         V4L2_DV_BT_DMT_1366X768P60,
  91         V4L2_DV_BT_DMT_1366X768P60_RB,
  92         V4L2_DV_BT_DMT_1400X1050P60_RB,
  93         V4L2_DV_BT_DMT_1400X1050P60,
  94         V4L2_DV_BT_DMT_1400X1050P75,
  95         V4L2_DV_BT_DMT_1400X1050P85,
  96         V4L2_DV_BT_DMT_1400X1050P120_RB,
  97         V4L2_DV_BT_DMT_1440X900P60_RB,
  98         V4L2_DV_BT_DMT_1440X900P60,
  99         V4L2_DV_BT_DMT_1440X900P75,
 100         V4L2_DV_BT_DMT_1440X900P85,
 101         V4L2_DV_BT_DMT_1440X900P120_RB,
 102         V4L2_DV_BT_DMT_1600X900P60_RB,
 103         V4L2_DV_BT_DMT_1600X1200P60,
 104         V4L2_DV_BT_DMT_1600X1200P65,
 105         V4L2_DV_BT_DMT_1600X1200P70,
 106         V4L2_DV_BT_DMT_1600X1200P75,
 107         V4L2_DV_BT_DMT_1600X1200P85,
 108         V4L2_DV_BT_DMT_1600X1200P120_RB,
 109         V4L2_DV_BT_DMT_1680X1050P60_RB,
 110         V4L2_DV_BT_DMT_1680X1050P60,
 111         V4L2_DV_BT_DMT_1680X1050P75,
 112         V4L2_DV_BT_DMT_1680X1050P85,
 113         V4L2_DV_BT_DMT_1680X1050P120_RB,
 114         V4L2_DV_BT_DMT_1792X1344P60,
 115         V4L2_DV_BT_DMT_1792X1344P75,
 116         V4L2_DV_BT_DMT_1792X1344P120_RB,
 117         V4L2_DV_BT_DMT_1856X1392P60,
 118         V4L2_DV_BT_DMT_1856X1392P75,
 119         V4L2_DV_BT_DMT_1856X1392P120_RB,
 120         V4L2_DV_BT_DMT_1920X1200P60_RB,
 121         V4L2_DV_BT_DMT_1920X1200P60,
 122         V4L2_DV_BT_DMT_1920X1200P75,
 123         V4L2_DV_BT_DMT_1920X1200P85,
 124         V4L2_DV_BT_DMT_1920X1200P120_RB,
 125         V4L2_DV_BT_DMT_1920X1440P60,
 126         V4L2_DV_BT_DMT_1920X1440P75,
 127         V4L2_DV_BT_DMT_1920X1440P120_RB,
 128         V4L2_DV_BT_DMT_2048X1152P60_RB,
 129         V4L2_DV_BT_DMT_2560X1600P60_RB,
 130         V4L2_DV_BT_DMT_2560X1600P60,
 131         V4L2_DV_BT_DMT_2560X1600P75,
 132         V4L2_DV_BT_DMT_2560X1600P85,
 133         V4L2_DV_BT_DMT_2560X1600P120_RB,
 134         V4L2_DV_BT_CEA_3840X2160P24,
 135         V4L2_DV_BT_CEA_3840X2160P25,
 136         V4L2_DV_BT_CEA_3840X2160P30,
 137         V4L2_DV_BT_CEA_3840X2160P50,
 138         V4L2_DV_BT_CEA_3840X2160P60,
 139         V4L2_DV_BT_CEA_4096X2160P24,
 140         V4L2_DV_BT_CEA_4096X2160P25,
 141         V4L2_DV_BT_CEA_4096X2160P30,
 142         V4L2_DV_BT_CEA_4096X2160P50,
 143         V4L2_DV_BT_DMT_4096X2160P59_94_RB,
 144         V4L2_DV_BT_CEA_4096X2160P60,
 145         { }
 146 };
 147 EXPORT_SYMBOL_GPL(v4l2_dv_timings_presets);
 148
 149 bool v4l2_valid_dv_timings(const struct v4l2_dv_timings *t,
 150                            const struct v4l2_dv_timings_cap *dvcap,
 151                            v4l2_check_dv_timings_fnc fnc,
 152                            void *fnc_handle)
 153 {
 154         const struct v4l2_bt_timings *bt = &t->bt;
 155         const struct v4l2_bt_timings_cap *cap = &dvcap->bt;
 156         u32 caps = cap->capabilities;
 157
 158         if (t->type != V4L2_DV_BT_656_1120)
 159                 return false;
 160         if (t->type != dvcap->type ||
 161             bt->height < cap->min_height ||
 162             bt->height > cap->max_height ||
 163             bt->width < cap->min_width ||
 164             bt->width > cap->max_width ||
 165             bt->pixelclock < cap->min_pixelclock ||
 166             bt->pixelclock > cap->max_pixelclock ||
 167             (cap->standards && bt->standards &&
 168              !(bt->standards & cap->standards)) ||
 169             (bt->interlaced && !(caps & V4L2_DV_BT_CAP_INTERLACED)) ||
 170             (!bt->interlaced && !(caps & V4L2_DV_BT_CAP_PROGRESSIVE)))
 171                 return false;
 172         return fnc == NULL || fnc(t, fnc_handle);
 173 }
 174 EXPORT_SYMBOL_GPL(v4l2_valid_dv_timings);
 175
 176 int v4l2_enum_dv_timings_cap(struct v4l2_enum_dv_timings *t,
 177                              const struct v4l2_dv_timings_cap *cap,
 178                              v4l2_check_dv_timings_fnc fnc,
 179                              void *fnc_handle)
 180 {
 181         u32 i, idx;
 182
 183         memset(t->reserved, 0, sizeof(t->reserved));
 184         for (i = idx = 0; v4l2_dv_timings_presets[i].bt.width; i++) {
 185                 if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
 186                                           fnc, fnc_handle) &&
 187                     idx++ == t->index) {
 188                         t->timings = v4l2_dv_timings_presets[i];
 189                         return 0;
 190                 }
 191         }
 192         return -EINVAL;
 193 }
 194 EXPORT_SYMBOL_GPL(v4l2_enum_dv_timings_cap);
 195
 196 bool v4l2_find_dv_timings_cap(struct v4l2_dv_timings *t,
 197                               const struct v4l2_dv_timings_cap *cap,
 198                               unsigned pclock_delta,
 199                               v4l2_check_dv_timings_fnc fnc,
 200                               void *fnc_handle)
 201 {
 202         int i;
 203
 204         if (!v4l2_valid_dv_timings(t, cap, fnc, fnc_handle))
 205                 return false;
 206
 207         for (i = 0; i < v4l2_dv_timings_presets[i].bt.width; i++) {
 208                 if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
 209                                           fnc, fnc_handle) &&
 210                     v4l2_match_dv_timings(t, v4l2_dv_timings_presets + i,
 211                                           pclock_delta)) {
 212                         *t = v4l2_dv_timings_presets[i];
 213                         return true;
 214                 }
 215         }
 216         return false;
 217 }
 218 EXPORT_SYMBOL_GPL(v4l2_find_dv_timings_cap);
 219
 220 /**
 221  * v4l2_match_dv_timings - check if two timings match
 222  * @t1 - compare this v4l2_dv_timings struct...
 223  * @t2 - with this struct.
 224  * @pclock_delta - the allowed pixelclock deviation.
 225  *
 226  * Compare t1 with t2 with a given margin of error for the pixelclock.
 227  */
 228 bool v4l2_match_dv_timings(const struct v4l2_dv_timings *t1,
 229                            const struct v4l2_dv_timings *t2,
 230                            unsigned pclock_delta)
 231 {
 232         if (t1->type != t2->type || t1->type != V4L2_DV_BT_656_1120)
 233                 return false;
 234         if (t1->bt.width == t2->bt.width &&
 235             t1->bt.height == t2->bt.height &&
 236             t1->bt.interlaced == t2->bt.interlaced &&
 237             t1->bt.polarities == t2->bt.polarities &&
 238             t1->bt.pixelclock >= t2->bt.pixelclock - pclock_delta &&
 239             t1->bt.pixelclock <= t2->bt.pixelclock + pclock_delta &&
 240             t1->bt.hfrontporch == t2->bt.hfrontporch &&
 241             t1->bt.vfrontporch == t2->bt.vfrontporch &&
 242             t1->bt.vsync == t2->bt.vsync &&
 243             t1->bt.vbackporch == t2->bt.vbackporch &&
 244             (!t1->bt.interlaced ||
 245                 (t1->bt.il_vfrontporch == t2->bt.il_vfrontporch &&
 246                  t1->bt.il_vsync == t2->bt.il_vsync &&
 247                  t1->bt.il_vbackporch == t2->bt.il_vbackporch)))
 248                 return true;
 249         return false;
 250 }
 251 EXPORT_SYMBOL_GPL(v4l2_match_dv_timings);
 252
 253 void v4l2_print_dv_timings(const char *dev_prefix, const char *prefix,
 254                            const struct v4l2_dv_timings *t, bool detailed)
 255 {
 256         const struct v4l2_bt_timings *bt = &t->bt;
 257         u32 htot, vtot;
 258
 259         if (t->type != V4L2_DV_BT_656_1120)
 260                 return;
 261
 262         htot = V4L2_DV_BT_FRAME_WIDTH(bt);
 263         vtot = V4L2_DV_BT_FRAME_HEIGHT(bt);
 264
 265         if (prefix == NULL)
 266                 prefix = "";
 267
 268         pr_info("%s: %s%ux%u%s%u (%ux%u)\n", dev_prefix, prefix,
 269                 bt->width, bt->height, bt->interlaced ? "i" : "p",
 270                 (htot * vtot) > 0 ? ((u32)bt->pixelclock / (htot * vtot)) : 0,
 271                 htot, vtot);
 272
 273         if (!detailed)
 274                 return;
 275
 276         pr_info("%s: horizontal: fp = %u, %ssync = %u, bp = %u\n",
 277                         dev_prefix, bt->hfrontporch,
 278                         (bt->polarities & V4L2_DV_HSYNC_POS_POL) ? "+" : "-",
 279                         bt->hsync, bt->hbackporch);
 280         pr_info("%s: vertical: fp = %u, %ssync = %u, bp = %u\n",
 281                         dev_prefix, bt->vfrontporch,
 282                         (bt->polarities & V4L2_DV_VSYNC_POS_POL) ? "+" : "-",
 283                         bt->vsync, bt->vbackporch);
 284         pr_info("%s: pixelclock: %llu\n", dev_prefix, bt->pixelclock);
 285         pr_info("%s: flags (0x%x):%s%s%s%s%s\n", dev_prefix, bt->flags,
 286                         (bt->flags & V4L2_DV_FL_REDUCED_BLANKING) ?
 287                         " REDUCED_BLANKING" : "",
 288                         (bt->flags & V4L2_DV_FL_CAN_REDUCE_FPS) ?
 289                         " CAN_REDUCE_FPS" : "",
 290                         (bt->flags & V4L2_DV_FL_REDUCED_FPS) ?
 291                         " REDUCED_FPS" : "",
 292                         (bt->flags & V4L2_DV_FL_HALF_LINE) ?
 293                         " HALF_LINE" : "",
 294                         (bt->flags & V4L2_DV_FL_IS_CE_VIDEO) ?
 295                         " CE_VIDEO" : "");
 296         pr_info("%s: standards (0x%x):%s%s%s%s\n", dev_prefix, bt->standards,
 297                         (bt->standards & V4L2_DV_BT_STD_CEA861) ?  " CEA" : "",
 298                         (bt->standards & V4L2_DV_BT_STD_DMT) ?  " DMT" : "",
 299                         (bt->standards & V4L2_DV_BT_STD_CVT) ?  " CVT" : "",
 300                         (bt->standards & V4L2_DV_BT_STD_GTF) ?  " GTF" : "");
 301 }
 302 EXPORT_SYMBOL_GPL(v4l2_print_dv_timings);
 303
 304 /*
 305  * CVT defines
 306  * Based on Coordinated Video Timings Standard
 307  * version 1.1 September 10, 2003
 308  */
 309
 310 #define CVT_PXL_CLK_GRAN        250000  /* pixel clock granularity */
 311
 312 /* Normal blanking */
 313 #define CVT_MIN_V_BPORCH        7       /* lines */
 314 #define CVT_MIN_V_PORCH_RND     3       /* lines */
 315 #define CVT_MIN_VSYNC_BP        550     /* min time of vsync + back porch (us) */
 316
 317 /* Normal blanking for CVT uses GTF to calculate horizontal blanking */
 318 #define CVT_CELL_GRAN           8       /* character cell granularity */
 319 #define CVT_M                   600     /* blanking formula gradient */
 320 #define CVT_C                   40      /* blanking formula offset */
 321 #define CVT_K                   128     /* blanking formula scaling factor */
 322 #define CVT_J                   20      /* blanking formula scaling factor */
 323 #define CVT_C_PRIME (((CVT_C - CVT_J) * CVT_K / 256) + CVT_J)
 324 #define CVT_M_PRIME (CVT_K * CVT_M / 256)
 325
 326 /* Reduced Blanking */
 327 #define CVT_RB_MIN_V_BPORCH    7       /* lines  */
 328 #define CVT_RB_V_FPORCH        3       /* lines  */
 329 #define CVT_RB_MIN_V_BLANK   460     /* us     */
 330 #define CVT_RB_H_SYNC         32       /* pixels */
 331 #define CVT_RB_H_BPORCH       80       /* pixels */
 332 #define CVT_RB_H_BLANK       160       /* pixels */
 333
 334 /** v4l2_detect_cvt - detect if the given timings follow the CVT standard
 335  * @frame_height - the total height of the frame (including blanking) in lines.
 336  * @hfreq - the horizontal frequency in Hz.
 337  * @vsync - the height of the vertical sync in lines.
 338  * @polarities - the horizontal and vertical polarities (same as struct
 339  *              v4l2_bt_timings polarities).
 340  * @fmt - the resulting timings.
 341  *
 342  * This function will attempt to detect if the given values correspond to a
 343  * valid CVT format. If so, then it will return true, and fmt will be filled
 344  * in with the found CVT timings.
 345  *
 346  * TODO: VESA defined a new version 2 of their reduced blanking
 347  * formula. Support for that is currently missing in this CVT
 348  * detection function.
 349  */
 350 bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
 351                 u32 polarities, struct v4l2_dv_timings *fmt)
 352 {
 353         int  v_fp, v_bp, h_fp, h_bp, hsync;
 354         int  frame_width, image_height, image_width;
 355         bool reduced_blanking;
 356         unsigned pix_clk;
 357
 358         if (vsync < 4 || vsync > 7)
 359                 return false;
 360
 361         if (polarities == V4L2_DV_VSYNC_POS_POL)
 362                 reduced_blanking = false;
 363         else if (polarities == V4L2_DV_HSYNC_POS_POL)
 364                 reduced_blanking = true;
 365         else
 366                 return false;
 367
 368         /* Vertical */
 369         if (reduced_blanking) {
 370                 v_fp = CVT_RB_V_FPORCH;
 371                 v_bp = (CVT_RB_MIN_V_BLANK * hfreq + 1999999) / 1000000;
 372                 v_bp -= vsync + v_fp;
 373
 374                 if (v_bp < CVT_RB_MIN_V_BPORCH)
 375                         v_bp = CVT_RB_MIN_V_BPORCH;
 376         } else {
 377                 v_fp = CVT_MIN_V_PORCH_RND;
 378                 v_bp = (CVT_MIN_VSYNC_BP * hfreq + 1999999) / 1000000 - vsync;
 379
 380                 if (v_bp < CVT_MIN_V_BPORCH)
 381                         v_bp = CVT_MIN_V_BPORCH;
 382         }
 383         image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;
 384
 385         /* Aspect ratio based on vsync */
 386         switch (vsync) {
 387         case 4:
 388                 image_width = (image_height * 4) / 3;
 389                 break;
 390         case 5:
 391                 image_width = (image_height * 16) / 9;
 392                 break;
 393         case 6:
 394                 image_width = (image_height * 16) / 10;
 395                 break;
 396         case 7:
 397                 /* special case */
 398                 if (image_height == 1024)
 399                         image_width = (image_height * 5) / 4;
 400                 else if (image_height == 768)
 401                         image_width = (image_height * 15) / 9;
 402                 else
 403                         return false;
 404                 break;
 405         default:
 406                 return false;
 407         }
 408
 409         image_width = image_width & ~7;
 410
 411         /* Horizontal */
 412         if (reduced_blanking) {
 413                 pix_clk = (image_width + CVT_RB_H_BLANK) * hfreq;
 414                 pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;
 415
 416                 h_bp = CVT_RB_H_BPORCH;
 417                 hsync = CVT_RB_H_SYNC;
 418                 h_fp = CVT_RB_H_BLANK - h_bp - hsync;
 419
 420                 frame_width = image_width + CVT_RB_H_BLANK;
 421         } else {
 422                 unsigned ideal_duty_cycle_per_myriad =
 423                         100 * CVT_C_PRIME - (CVT_M_PRIME * 100000) / hfreq;
 424                 int h_blank;
 425
 426                 if (ideal_duty_cycle_per_myriad < 2000)
 427                         ideal_duty_cycle_per_myriad = 2000;
 428
 429                 h_blank = image_width * ideal_duty_cycle_per_myriad /
 430                                         (10000 - ideal_duty_cycle_per_myriad);
 431                 h_blank = (h_blank / (2 * CVT_CELL_GRAN)) * 2 * CVT_CELL_GRAN;
 432
 433                 pix_clk = (image_width + h_blank) * hfreq;
 434                 pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;
 435
 436                 h_bp = h_blank / 2;
 437                 frame_width = image_width + h_blank;
 438
 439                 hsync = (frame_width * 8 + 50) / 100;
 440                 hsync = hsync - hsync % CVT_CELL_GRAN;
 441                 h_fp = h_blank - hsync - h_bp;
 442         }
 443
 444         fmt->type = V4L2_DV_BT_656_1120;
 445         fmt->bt.polarities = polarities;
 446         fmt->bt.width = image_width;
 447         fmt->bt.height = image_height;
 448         fmt->bt.hfrontporch = h_fp;
 449         fmt->bt.vfrontporch = v_fp;
 450         fmt->bt.hsync = hsync;
 451         fmt->bt.vsync = vsync;
 452         fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
 453         fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
 454         fmt->bt.pixelclock = pix_clk;
 455         fmt->bt.standards = V4L2_DV_BT_STD_CVT;
 456         if (reduced_blanking)
 457                 fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
 458         return true;
 459 }
 460 EXPORT_SYMBOL_GPL(v4l2_detect_cvt);
 461
 462 /*
 463  * GTF defines
 464  * Based on Generalized Timing Formula Standard
 465  * Version 1.1 September 2, 1999
 466  */
 467
 468 #define GTF_PXL_CLK_GRAN        250000  /* pixel clock granularity */
 469
 470 #define GTF_MIN_VSYNC_BP        550     /* min time of vsync + back porch (us) */
 471 #define GTF_V_FP                1       /* vertical front porch (lines) */
 472 #define GTF_CELL_GRAN           8       /* character cell granularity */
 473
 474 /* Default */
 475 #define GTF_D_M                 600     /* blanking formula gradient */
 476 #define GTF_D_C                 40      /* blanking formula offset */
 477 #define GTF_D_K                 128     /* blanking formula scaling factor */
 478 #define GTF_D_J                 20      /* blanking formula scaling factor */
 479 #define GTF_D_C_PRIME ((((GTF_D_C - GTF_D_J) * GTF_D_K) / 256) + GTF_D_J)
 480 #define GTF_D_M_PRIME ((GTF_D_K * GTF_D_M) / 256)
 481
 482 /* Secondary */
 483 #define GTF_S_M                 3600    /* blanking formula gradient */
 484 #define GTF_S_C                 40      /* blanking formula offset */
 485 #define GTF_S_K                 128     /* blanking formula scaling factor */
 486 #define GTF_S_J                 35      /* blanking formula scaling factor */
 487 #define GTF_S_C_PRIME ((((GTF_S_C - GTF_S_J) * GTF_S_K) / 256) + GTF_S_J)
 488 #define GTF_S_M_PRIME ((GTF_S_K * GTF_S_M) / 256)
 489
 490 /** v4l2_detect_gtf - detect if the given timings follow the GTF standard
 491  * @frame_height - the total height of the frame (including blanking) in lines.
 492  * @hfreq - the horizontal frequency in Hz.
 493  * @vsync - the height of the vertical sync in lines.
 494  * @polarities - the horizontal and vertical polarities (same as struct
 495  *              v4l2_bt_timings polarities).
 496  * @aspect - preferred aspect ratio. GTF has no method of determining the
 497  *              aspect ratio in order to derive the image width from the
 498  *              image height, so it has to be passed explicitly. Usually
 499  *              the native screen aspect ratio is used for this. If it
 500  *              is not filled in correctly, then 16:9 will be assumed.
 501  * @fmt - the resulting timings.
 502  *
 503  * This function will attempt to detect if the given values correspond to a
 504  * valid GTF format. If so, then it will return true, and fmt will be filled
 505  * in with the found GTF timings.
 506  */
 507 bool v4l2_detect_gtf(unsigned frame_height,
 508                 unsigned hfreq,
 509                 unsigned vsync,
 510                 u32 polarities,
 511                 struct v4l2_fract aspect,
 512                 struct v4l2_dv_timings *fmt)
 513 {
 514         int pix_clk;
 515         int  v_fp, v_bp, h_fp, hsync;
 516         int frame_width, image_height, image_width;
 517         bool default_gtf;
 518         int h_blank;
 519
 520         if (vsync != 3)
 521                 return false;
 522
 523         if (polarities == V4L2_DV_VSYNC_POS_POL)
 524                 default_gtf = true;
 525         else if (polarities == V4L2_DV_HSYNC_POS_POL)
 526                 default_gtf = false;
 527         else
 528                 return false;
 529
 530         /* Vertical */
 531         v_fp = GTF_V_FP;
 532         v_bp = (GTF_MIN_VSYNC_BP * hfreq + 999999) / 1000000 - vsync;
 533         image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;
 534
 535         if (aspect.numerator == 0 || aspect.denominator == 0) {
 536                 aspect.numerator = 16;
 537                 aspect.denominator = 9;
 538         }
 539         image_width = ((image_height * aspect.numerator) / aspect.denominator);
 540         image_width = (image_width + GTF_CELL_GRAN/2) & ~(GTF_CELL_GRAN - 1);
 541
 542         /* Horizontal */
 543         if (default_gtf)
 544                 h_blank = ((image_width * GTF_D_C_PRIME * hfreq) -
 545                                         (image_width * GTF_D_M_PRIME * 1000) +
 546                         (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000) / 2) /
 547                         (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000);
 548         else
 549                 h_blank = ((image_width * GTF_S_C_PRIME * hfreq) -
 550                                         (image_width * GTF_S_M_PRIME * 1000) +
 551                         (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000) / 2) /
 552                         (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000);
 553
 554         h_blank = h_blank - h_blank % (2 * GTF_CELL_GRAN);
 555         frame_width = image_width + h_blank;
 556
 557         pix_clk = (image_width + h_blank) * hfreq;
 558         pix_clk = pix_clk / GTF_PXL_CLK_GRAN * GTF_PXL_CLK_GRAN;
 559
 560         hsync = (frame_width * 8 + 50) / 100;
 561         hsync = hsync - hsync % GTF_CELL_GRAN;
 562
 563         h_fp = h_blank / 2 - hsync;
 564
 565         fmt->type = V4L2_DV_BT_656_1120;
 566         fmt->bt.polarities = polarities;
 567         fmt->bt.width = image_width;
 568         fmt->bt.height = image_height;
 569         fmt->bt.hfrontporch = h_fp;
 570         fmt->bt.vfrontporch = v_fp;
 571         fmt->bt.hsync = hsync;
 572         fmt->bt.vsync = vsync;
 573         fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
 574         fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
 575         fmt->bt.pixelclock = pix_clk;
 576         fmt->bt.standards = V4L2_DV_BT_STD_GTF;
 577         if (!default_gtf)
 578                 fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
 579         return true;
 580 }
 581 EXPORT_SYMBOL_GPL(v4l2_detect_gtf);
 582
 583 /** v4l2_calc_aspect_ratio - calculate the aspect ratio based on bytes
 584  *      0x15 and 0x16 from the EDID.
 585  * @hor_landscape - byte 0x15 from the EDID.
 586  * @vert_portrait - byte 0x16 from the EDID.
 587  *
 588  * Determines the aspect ratio from the EDID.
 589  * See VESA Enhanced EDID standard, release A, rev 2, section 3.6.2:
 590  * "Horizontal and Vertical Screen Size or Aspect Ratio"
 591  */
 592 struct v4l2_fract v4l2_calc_aspect_ratio(u8 hor_landscape, u8 vert_portrait)
 593 {
 594         struct v4l2_fract aspect = { 16, 9 };
 595         u32 tmp;
 596         u8 ratio;
 597
 598         /* Nothing filled in, fallback to 16:9 */
 599         if (!hor_landscape && !vert_portrait)
 600                 return aspect;
 601         /* Both filled in, so they are interpreted as the screen size in cm */
 602         if (hor_landscape && vert_portrait) {
 603                 aspect.numerator = hor_landscape;
 604                 aspect.denominator = vert_portrait;
 605                 return aspect;
 606         }
 607         /* Only one is filled in, so interpret them as a ratio:
 608            (val + 99) / 100 */
 609         ratio = hor_landscape | vert_portrait;
 610         /* Change some rounded values into the exact aspect ratio */
 611         if (ratio == 79) {
 612                 aspect.numerator = 16;
 613                 aspect.denominator = 9;
 614         } else if (ratio == 34) {
 615                 aspect.numerator = 4;
 616                 aspect.denominator = 3;
 617         } else if (ratio == 68) {
 618                 aspect.numerator = 15;
 619                 aspect.denominator = 9;
 620         } else {
 621                 aspect.numerator = hor_landscape + 99;
 622                 aspect.denominator = 100;
 623         }
 624         if (hor_landscape)
 625                 return aspect;
 626         /* The aspect ratio is for portrait, so swap numerator and denominator */
 627         tmp = aspect.denominator;
 628         aspect.denominator = aspect.numerator;
 629         aspect.numerator = tmp;
 630         return aspect;
 631 }
 632 EXPORT_SYMBOL_GPL(v4l2_calc_aspect_ratio);