linux/drivers/media/v4l2-core/v4l2-dv-timings.c
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   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
  29MODULE_AUTHOR("Hans Verkuil");
  30MODULE_DESCRIPTION("V4L2 DV Timings Helper Functions");
  31MODULE_LICENSE("GPL");
  32
  33const 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};
 147EXPORT_SYMBOL_GPL(v4l2_dv_timings_presets);
 148
 149bool 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}
 174EXPORT_SYMBOL_GPL(v4l2_valid_dv_timings);
 175
 176int 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}
 194EXPORT_SYMBOL_GPL(v4l2_enum_dv_timings_cap);
 195
 196bool 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}
 218EXPORT_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 */
 228bool 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}
 251EXPORT_SYMBOL_GPL(v4l2_match_dv_timings);
 252
 253void 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}
 302EXPORT_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 */
 350bool 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}
 460EXPORT_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 */
 507bool 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}
 581EXPORT_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 */
 592struct 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}
 632EXPORT_SYMBOL_GPL(v4l2_calc_aspect_ratio);
 633