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         { }
 135 };
 136 EXPORT_SYMBOL_GPL(v4l2_dv_timings_presets);
 137
 138 bool v4l2_valid_dv_timings(const struct v4l2_dv_timings *t,
 139                            const struct v4l2_dv_timings_cap *dvcap,
 140                            v4l2_check_dv_timings_fnc fnc,
 141                            void *fnc_handle)
 142 {
 143         const struct v4l2_bt_timings *bt = &t->bt;
 144         const struct v4l2_bt_timings_cap *cap = &dvcap->bt;
 145         u32 caps = cap->capabilities;
 146
 147         if (t->type != V4L2_DV_BT_656_1120)
 148                 return false;
 149         if (t->type != dvcap->type ||
 150             bt->height < cap->min_height ||
 151             bt->height > cap->max_height ||
 152             bt->width < cap->min_width ||
 153             bt->width > cap->max_width ||
 154             bt->pixelclock < cap->min_pixelclock ||
 155             bt->pixelclock > cap->max_pixelclock ||
 156             (cap->standards && !(bt->standards & cap->standards)) ||
 157             (bt->interlaced && !(caps & V4L2_DV_BT_CAP_INTERLACED)) ||
 158             (!bt->interlaced && !(caps & V4L2_DV_BT_CAP_PROGRESSIVE)))
 159                 return false;
 160         return fnc == NULL || fnc(t, fnc_handle);
 161 }
 162 EXPORT_SYMBOL_GPL(v4l2_valid_dv_timings);
 163
 164 int v4l2_enum_dv_timings_cap(struct v4l2_enum_dv_timings *t,
 165                              const struct v4l2_dv_timings_cap *cap,
 166                              v4l2_check_dv_timings_fnc fnc,
 167                              void *fnc_handle)
 168 {
 169         u32 i, idx;
 170
 171         memset(t->reserved, 0, sizeof(t->reserved));
 172         for (i = idx = 0; v4l2_dv_timings_presets[i].bt.width; i++) {
 173                 if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
 174                                           fnc, fnc_handle) &&
 175                     idx++ == t->index) {
 176                         t->timings = v4l2_dv_timings_presets[i];
 177                         return 0;
 178                 }
 179         }
 180         return -EINVAL;
 181 }
 182 EXPORT_SYMBOL_GPL(v4l2_enum_dv_timings_cap);
 183
 184 bool v4l2_find_dv_timings_cap(struct v4l2_dv_timings *t,
 185                               const struct v4l2_dv_timings_cap *cap,
 186                               unsigned pclock_delta,
 187                               v4l2_check_dv_timings_fnc fnc,
 188                               void *fnc_handle)
 189 {
 190         int i;
 191
 192         if (!v4l2_valid_dv_timings(t, cap, fnc, fnc_handle))
 193                 return false;
 194
 195         for (i = 0; i < v4l2_dv_timings_presets[i].bt.width; i++) {
 196                 if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
 197                                           fnc, fnc_handle) &&
 198                     v4l2_match_dv_timings(t, v4l2_dv_timings_presets + i,
 199                                           pclock_delta)) {
 200                         *t = v4l2_dv_timings_presets[i];
 201                         return true;
 202                 }
 203         }
 204         return false;
 205 }
 206 EXPORT_SYMBOL_GPL(v4l2_find_dv_timings_cap);
 207
 208 /**
 209  * v4l2_match_dv_timings - check if two timings match
 210  * @t1 - compare this v4l2_dv_timings struct...
 211  * @t2 - with this struct.
 212  * @pclock_delta - the allowed pixelclock deviation.
 213  *
 214  * Compare t1 with t2 with a given margin of error for the pixelclock.
 215  */
 216 bool v4l2_match_dv_timings(const struct v4l2_dv_timings *t1,
 217                            const struct v4l2_dv_timings *t2,
 218                            unsigned pclock_delta)
 219 {
 220         if (t1->type != t2->type || t1->type != V4L2_DV_BT_656_1120)
 221                 return false;
 222         if (t1->bt.width == t2->bt.width &&
 223             t1->bt.height == t2->bt.height &&
 224             t1->bt.interlaced == t2->bt.interlaced &&
 225             t1->bt.polarities == t2->bt.polarities &&
 226             t1->bt.pixelclock >= t2->bt.pixelclock - pclock_delta &&
 227             t1->bt.pixelclock <= t2->bt.pixelclock + pclock_delta &&
 228             t1->bt.hfrontporch == t2->bt.hfrontporch &&
 229             t1->bt.vfrontporch == t2->bt.vfrontporch &&
 230             t1->bt.vsync == t2->bt.vsync &&
 231             t1->bt.vbackporch == t2->bt.vbackporch &&
 232             (!t1->bt.interlaced ||
 233                 (t1->bt.il_vfrontporch == t2->bt.il_vfrontporch &&
 234                  t1->bt.il_vsync == t2->bt.il_vsync &&
 235                  t1->bt.il_vbackporch == t2->bt.il_vbackporch)))
 236                 return true;
 237         return false;
 238 }
 239 EXPORT_SYMBOL_GPL(v4l2_match_dv_timings);
 240
 241 void v4l2_print_dv_timings(const char *dev_prefix, const char *prefix,
 242                            const struct v4l2_dv_timings *t, bool detailed)
 243 {
 244         const struct v4l2_bt_timings *bt = &t->bt;
 245         u32 htot, vtot;
 246
 247         if (t->type != V4L2_DV_BT_656_1120)
 248                 return;
 249
 250         htot = V4L2_DV_BT_FRAME_WIDTH(bt);
 251         vtot = V4L2_DV_BT_FRAME_HEIGHT(bt);
 252
 253         if (prefix == NULL)
 254                 prefix = "";
 255
 256         pr_info("%s: %s%ux%u%s%u (%ux%u)\n", dev_prefix, prefix,
 257                 bt->width, bt->height, bt->interlaced ? "i" : "p",
 258                 (htot * vtot) > 0 ? ((u32)bt->pixelclock / (htot * vtot)) : 0,
 259                 htot, vtot);
 260
 261         if (!detailed)
 262                 return;
 263
 264         pr_info("%s: horizontal: fp = %u, %ssync = %u, bp = %u\n",
 265                         dev_prefix, bt->hfrontporch,
 266                         (bt->polarities & V4L2_DV_HSYNC_POS_POL) ? "+" : "-",
 267                         bt->hsync, bt->hbackporch);
 268         pr_info("%s: vertical: fp = %u, %ssync = %u, bp = %u\n",
 269                         dev_prefix, bt->vfrontporch,
 270                         (bt->polarities & V4L2_DV_VSYNC_POS_POL) ? "+" : "-",
 271                         bt->vsync, bt->vbackporch);
 272         pr_info("%s: pixelclock: %llu\n", dev_prefix, bt->pixelclock);
 273         pr_info("%s: flags (0x%x):%s%s%s%s\n", dev_prefix, bt->flags,
 274                         (bt->flags & V4L2_DV_FL_REDUCED_BLANKING) ?
 275                         " REDUCED_BLANKING" : "",
 276                         (bt->flags & V4L2_DV_FL_CAN_REDUCE_FPS) ?
 277                         " CAN_REDUCE_FPS" : "",
 278                         (bt->flags & V4L2_DV_FL_REDUCED_FPS) ?
 279                         " REDUCED_FPS" : "",
 280                         (bt->flags & V4L2_DV_FL_HALF_LINE) ?
 281                         " HALF_LINE" : "");
 282         pr_info("%s: standards (0x%x):%s%s%s%s\n", dev_prefix, bt->standards,
 283                         (bt->standards & V4L2_DV_BT_STD_CEA861) ?  " CEA" : "",
 284                         (bt->standards & V4L2_DV_BT_STD_DMT) ?  " DMT" : "",
 285                         (bt->standards & V4L2_DV_BT_STD_CVT) ?  " CVT" : "",
 286                         (bt->standards & V4L2_DV_BT_STD_GTF) ?  " GTF" : "");
 287 }
 288 EXPORT_SYMBOL_GPL(v4l2_print_dv_timings);
 289
 290 /*
 291  * CVT defines
 292  * Based on Coordinated Video Timings Standard
 293  * version 1.1 September 10, 2003
 294  */
 295
 296 #define CVT_PXL_CLK_GRAN        250000  /* pixel clock granularity */
 297
 298 /* Normal blanking */
 299 #define CVT_MIN_V_BPORCH        7       /* lines */
 300 #define CVT_MIN_V_PORCH_RND     3       /* lines */
 301 #define CVT_MIN_VSYNC_BP        550     /* min time of vsync + back porch (us) */
 302
 303 /* Normal blanking for CVT uses GTF to calculate horizontal blanking */
 304 #define CVT_CELL_GRAN           8       /* character cell granularity */
 305 #define CVT_M                   600     /* blanking formula gradient */
 306 #define CVT_C                   40      /* blanking formula offset */
 307 #define CVT_K                   128     /* blanking formula scaling factor */
 308 #define CVT_J                   20      /* blanking formula scaling factor */
 309 #define CVT_C_PRIME (((CVT_C - CVT_J) * CVT_K / 256) + CVT_J)
 310 #define CVT_M_PRIME (CVT_K * CVT_M / 256)
 311
 312 /* Reduced Blanking */
 313 #define CVT_RB_MIN_V_BPORCH    7       /* lines  */
 314 #define CVT_RB_V_FPORCH        3       /* lines  */
 315 #define CVT_RB_MIN_V_BLANK   460     /* us     */
 316 #define CVT_RB_H_SYNC         32       /* pixels */
 317 #define CVT_RB_H_BPORCH       80       /* pixels */
 318 #define CVT_RB_H_BLANK       160       /* pixels */
 319
 320 /** v4l2_detect_cvt - detect if the given timings follow the CVT standard
 321  * @frame_height - the total height of the frame (including blanking) in lines.
 322  * @hfreq - the horizontal frequency in Hz.
 323  * @vsync - the height of the vertical sync in lines.
 324  * @polarities - the horizontal and vertical polarities (same as struct
 325  *              v4l2_bt_timings polarities).
 326  * @fmt - the resulting timings.
 327  *
 328  * This function will attempt to detect if the given values correspond to a
 329  * valid CVT format. If so, then it will return true, and fmt will be filled
 330  * in with the found CVT timings.
 331  */
 332 bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
 333                 u32 polarities, struct v4l2_dv_timings *fmt)
 334 {
 335         int  v_fp, v_bp, h_fp, h_bp, hsync;
 336         int  frame_width, image_height, image_width;
 337         bool reduced_blanking;
 338         unsigned pix_clk;
 339
 340         if (vsync < 4 || vsync > 7)
 341                 return false;
 342
 343         if (polarities == V4L2_DV_VSYNC_POS_POL)
 344                 reduced_blanking = false;
 345         else if (polarities == V4L2_DV_HSYNC_POS_POL)
 346                 reduced_blanking = true;
 347         else
 348                 return false;
 349
 350         /* Vertical */
 351         if (reduced_blanking) {
 352                 v_fp = CVT_RB_V_FPORCH;
 353                 v_bp = (CVT_RB_MIN_V_BLANK * hfreq + 1999999) / 1000000;
 354                 v_bp -= vsync + v_fp;
 355
 356                 if (v_bp < CVT_RB_MIN_V_BPORCH)
 357                         v_bp = CVT_RB_MIN_V_BPORCH;
 358         } else {
 359                 v_fp = CVT_MIN_V_PORCH_RND;
 360                 v_bp = (CVT_MIN_VSYNC_BP * hfreq + 1999999) / 1000000 - vsync;
 361
 362                 if (v_bp < CVT_MIN_V_BPORCH)
 363                         v_bp = CVT_MIN_V_BPORCH;
 364         }
 365         image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;
 366
 367         /* Aspect ratio based on vsync */
 368         switch (vsync) {
 369         case 4:
 370                 image_width = (image_height * 4) / 3;
 371                 break;
 372         case 5:
 373                 image_width = (image_height * 16) / 9;
 374                 break;
 375         case 6:
 376                 image_width = (image_height * 16) / 10;
 377                 break;
 378         case 7:
 379                 /* special case */
 380                 if (image_height == 1024)
 381                         image_width = (image_height * 5) / 4;
 382                 else if (image_height == 768)
 383                         image_width = (image_height * 15) / 9;
 384                 else
 385                         return false;
 386                 break;
 387         default:
 388                 return false;
 389         }
 390
 391         image_width = image_width & ~7;
 392
 393         /* Horizontal */
 394         if (reduced_blanking) {
 395                 pix_clk = (image_width + CVT_RB_H_BLANK) * hfreq;
 396                 pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;
 397
 398                 h_bp = CVT_RB_H_BPORCH;
 399                 hsync = CVT_RB_H_SYNC;
 400                 h_fp = CVT_RB_H_BLANK - h_bp - hsync;
 401
 402                 frame_width = image_width + CVT_RB_H_BLANK;
 403         } else {
 404                 unsigned ideal_duty_cycle_per_myriad =
 405                         100 * CVT_C_PRIME - (CVT_M_PRIME * 100000) / hfreq;
 406                 int h_blank;
 407
 408                 if (ideal_duty_cycle_per_myriad < 2000)
 409                         ideal_duty_cycle_per_myriad = 2000;
 410
 411                 h_blank = image_width * ideal_duty_cycle_per_myriad /
 412                                         (10000 - ideal_duty_cycle_per_myriad);
 413                 h_blank = (h_blank / (2 * CVT_CELL_GRAN)) * 2 * CVT_CELL_GRAN;
 414
 415                 pix_clk = (image_width + h_blank) * hfreq;
 416                 pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;
 417
 418                 h_bp = h_blank / 2;
 419                 frame_width = image_width + h_blank;
 420
 421                 hsync = (frame_width * 8 + 50) / 100;
 422                 hsync = hsync - hsync % CVT_CELL_GRAN;
 423                 h_fp = h_blank - hsync - h_bp;
 424         }
 425
 426         fmt->type = V4L2_DV_BT_656_1120;
 427         fmt->bt.polarities = polarities;
 428         fmt->bt.width = image_width;
 429         fmt->bt.height = image_height;
 430         fmt->bt.hfrontporch = h_fp;
 431         fmt->bt.vfrontporch = v_fp;
 432         fmt->bt.hsync = hsync;
 433         fmt->bt.vsync = vsync;
 434         fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
 435         fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
 436         fmt->bt.pixelclock = pix_clk;
 437         fmt->bt.standards = V4L2_DV_BT_STD_CVT;
 438         if (reduced_blanking)
 439                 fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
 440         return true;
 441 }
 442 EXPORT_SYMBOL_GPL(v4l2_detect_cvt);
 443
 444 /*
 445  * GTF defines
 446  * Based on Generalized Timing Formula Standard
 447  * Version 1.1 September 2, 1999
 448  */
 449
 450 #define GTF_PXL_CLK_GRAN        250000  /* pixel clock granularity */
 451
 452 #define GTF_MIN_VSYNC_BP        550     /* min time of vsync + back porch (us) */
 453 #define GTF_V_FP                1       /* vertical front porch (lines) */
 454 #define GTF_CELL_GRAN           8       /* character cell granularity */
 455
 456 /* Default */
 457 #define GTF_D_M                 600     /* blanking formula gradient */
 458 #define GTF_D_C                 40      /* blanking formula offset */
 459 #define GTF_D_K                 128     /* blanking formula scaling factor */
 460 #define GTF_D_J                 20      /* blanking formula scaling factor */
 461 #define GTF_D_C_PRIME ((((GTF_D_C - GTF_D_J) * GTF_D_K) / 256) + GTF_D_J)
 462 #define GTF_D_M_PRIME ((GTF_D_K * GTF_D_M) / 256)
 463
 464 /* Secondary */
 465 #define GTF_S_M                 3600    /* blanking formula gradient */
 466 #define GTF_S_C                 40      /* blanking formula offset */
 467 #define GTF_S_K                 128     /* blanking formula scaling factor */
 468 #define GTF_S_J                 35      /* blanking formula scaling factor */
 469 #define GTF_S_C_PRIME ((((GTF_S_C - GTF_S_J) * GTF_S_K) / 256) + GTF_S_J)
 470 #define GTF_S_M_PRIME ((GTF_S_K * GTF_S_M) / 256)
 471
 472 /** v4l2_detect_gtf - detect if the given timings follow the GTF standard
 473  * @frame_height - the total height of the frame (including blanking) in lines.
 474  * @hfreq - the horizontal frequency in Hz.
 475  * @vsync - the height of the vertical sync in lines.
 476  * @polarities - the horizontal and vertical polarities (same as struct
 477  *              v4l2_bt_timings polarities).
 478  * @aspect - preferred aspect ratio. GTF has no method of determining the
 479  *              aspect ratio in order to derive the image width from the
 480  *              image height, so it has to be passed explicitly. Usually
 481  *              the native screen aspect ratio is used for this. If it
 482  *              is not filled in correctly, then 16:9 will be assumed.
 483  * @fmt - the resulting timings.
 484  *
 485  * This function will attempt to detect if the given values correspond to a
 486  * valid GTF format. If so, then it will return true, and fmt will be filled
 487  * in with the found GTF timings.
 488  */
 489 bool v4l2_detect_gtf(unsigned frame_height,
 490                 unsigned hfreq,
 491                 unsigned vsync,
 492                 u32 polarities,
 493                 struct v4l2_fract aspect,
 494                 struct v4l2_dv_timings *fmt)
 495 {
 496         int pix_clk;
 497         int  v_fp, v_bp, h_fp, hsync;
 498         int frame_width, image_height, image_width;
 499         bool default_gtf;
 500         int h_blank;
 501
 502         if (vsync != 3)
 503                 return false;
 504
 505         if (polarities == V4L2_DV_VSYNC_POS_POL)
 506                 default_gtf = true;
 507         else if (polarities == V4L2_DV_HSYNC_POS_POL)
 508                 default_gtf = false;
 509         else
 510                 return false;
 511
 512         /* Vertical */
 513         v_fp = GTF_V_FP;
 514         v_bp = (GTF_MIN_VSYNC_BP * hfreq + 999999) / 1000000 - vsync;
 515         image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;
 516
 517         if (aspect.numerator == 0 || aspect.denominator == 0) {
 518                 aspect.numerator = 16;
 519                 aspect.denominator = 9;
 520         }
 521         image_width = ((image_height * aspect.numerator) / aspect.denominator);
 522         image_width = (image_width + GTF_CELL_GRAN/2) & ~(GTF_CELL_GRAN - 1);
 523
 524         /* Horizontal */
 525         if (default_gtf)
 526                 h_blank = ((image_width * GTF_D_C_PRIME * hfreq) -
 527                                         (image_width * GTF_D_M_PRIME * 1000) +
 528                         (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000) / 2) /
 529                         (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000);
 530         else
 531                 h_blank = ((image_width * GTF_S_C_PRIME * hfreq) -
 532                                         (image_width * GTF_S_M_PRIME * 1000) +
 533                         (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000) / 2) /
 534                         (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000);
 535
 536         h_blank = h_blank - h_blank % (2 * GTF_CELL_GRAN);
 537         frame_width = image_width + h_blank;
 538
 539         pix_clk = (image_width + h_blank) * hfreq;
 540         pix_clk = pix_clk / GTF_PXL_CLK_GRAN * GTF_PXL_CLK_GRAN;
 541
 542         hsync = (frame_width * 8 + 50) / 100;
 543         hsync = hsync - hsync % GTF_CELL_GRAN;
 544
 545         h_fp = h_blank / 2 - hsync;
 546
 547         fmt->type = V4L2_DV_BT_656_1120;
 548         fmt->bt.polarities = polarities;
 549         fmt->bt.width = image_width;
 550         fmt->bt.height = image_height;
 551         fmt->bt.hfrontporch = h_fp;
 552         fmt->bt.vfrontporch = v_fp;
 553         fmt->bt.hsync = hsync;
 554         fmt->bt.vsync = vsync;
 555         fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
 556         fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
 557         fmt->bt.pixelclock = pix_clk;
 558         fmt->bt.standards = V4L2_DV_BT_STD_GTF;
 559         if (!default_gtf)
 560                 fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
 561         return true;
 562 }
 563 EXPORT_SYMBOL_GPL(v4l2_detect_gtf);
 564
 565 /** v4l2_calc_aspect_ratio - calculate the aspect ratio based on bytes
 566  *      0x15 and 0x16 from the EDID.
 567  * @hor_landscape - byte 0x15 from the EDID.
 568  * @vert_portrait - byte 0x16 from the EDID.
 569  *
 570  * Determines the aspect ratio from the EDID.
 571  * See VESA Enhanced EDID standard, release A, rev 2, section 3.6.2:
 572  * "Horizontal and Vertical Screen Size or Aspect Ratio"
 573  */
 574 struct v4l2_fract v4l2_calc_aspect_ratio(u8 hor_landscape, u8 vert_portrait)
 575 {
 576         struct v4l2_fract aspect = { 16, 9 };
 577         u32 tmp;
 578         u8 ratio;
 579
 580         /* Nothing filled in, fallback to 16:9 */
 581         if (!hor_landscape && !vert_portrait)
 582                 return aspect;
 583         /* Both filled in, so they are interpreted as the screen size in cm */
 584         if (hor_landscape && vert_portrait) {
 585                 aspect.numerator = hor_landscape;
 586                 aspect.denominator = vert_portrait;
 587                 return aspect;
 588         }
 589         /* Only one is filled in, so interpret them as a ratio:
 590            (val + 99) / 100 */
 591         ratio = hor_landscape | vert_portrait;
 592         /* Change some rounded values into the exact aspect ratio */
 593         if (ratio == 79) {
 594                 aspect.numerator = 16;
 595                 aspect.denominator = 9;
 596         } else if (ratio == 34) {
 597                 aspect.numerator = 4;
 598                 aspect.denominator = 3;
 599         } else if (ratio == 68) {
 600                 aspect.numerator = 15;
 601                 aspect.denominator = 9;
 602         } else {
 603                 aspect.numerator = hor_landscape + 99;
 604                 aspect.denominator = 100;
 605         }
 606         if (hor_landscape)
 607                 return aspect;
 608         /* The aspect ratio is for portrait, so swap numerator and denominator */
 609         tmp = aspect.denominator;
 610         aspect.denominator = aspect.numerator;
 611         aspect.numerator = tmp;
 612         return aspect;
 613 }
 614 EXPORT_SYMBOL_GPL(v4l2_calc_aspect_ratio);