linux/include/media/v4l2-dv-timings.h
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   1/*
   2 * v4l2-dv-timings - Internal header with 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#ifndef __V4L2_DV_TIMINGS_H
  22#define __V4L2_DV_TIMINGS_H
  23
  24#include <linux/videodev2.h>
  25
  26/*
  27 * v4l2_dv_timings_presets: list of all dv_timings presets.
  28 */
  29extern const struct v4l2_dv_timings v4l2_dv_timings_presets[];
  30
  31/**
  32 * v4l2_check_dv_timings_fnc - timings check callback
  33 *
  34 * @t: the v4l2_dv_timings struct.
  35 * @handle: a handle from the driver.
  36 *
  37 * Returns true if the given timings are valid.
  38 */
  39typedef bool v4l2_check_dv_timings_fnc(const struct v4l2_dv_timings *t, void *handle);
  40
  41/**
  42 * v4l2_valid_dv_timings() - are these timings valid?
  43 *
  44 * @t:    the v4l2_dv_timings struct.
  45 * @cap: the v4l2_dv_timings_cap capabilities.
  46 * @fnc: callback to check if this timing is OK. May be NULL.
  47 * @fnc_handle: a handle that is passed on to @fnc.
  48 *
  49 * Returns true if the given dv_timings struct is supported by the
  50 * hardware capabilities and the callback function (if non-NULL), returns
  51 * false otherwise.
  52 */
  53bool v4l2_valid_dv_timings(const struct v4l2_dv_timings *t,
  54                           const struct v4l2_dv_timings_cap *cap,
  55                           v4l2_check_dv_timings_fnc fnc,
  56                           void *fnc_handle);
  57
  58/**
  59 * v4l2_enum_dv_timings_cap() - Helper function to enumerate possible DV
  60 *       timings based on capabilities
  61 *
  62 * @t:    the v4l2_enum_dv_timings struct.
  63 * @cap: the v4l2_dv_timings_cap capabilities.
  64 * @fnc: callback to check if this timing is OK. May be NULL.
  65 * @fnc_handle: a handle that is passed on to @fnc.
  66 *
  67 * This enumerates dv_timings using the full list of possible CEA-861 and DMT
  68 * timings, filtering out any timings that are not supported based on the
  69 * hardware capabilities and the callback function (if non-NULL).
  70 *
  71 * If a valid timing for the given index is found, it will fill in @t and
  72 * return 0, otherwise it returns -EINVAL.
  73 */
  74int v4l2_enum_dv_timings_cap(struct v4l2_enum_dv_timings *t,
  75                             const struct v4l2_dv_timings_cap *cap,
  76                             v4l2_check_dv_timings_fnc fnc,
  77                             void *fnc_handle);
  78
  79/**
  80 * v4l2_find_dv_timings_cap() - Find the closest timings struct
  81 *
  82 * @t:    the v4l2_enum_dv_timings struct.
  83 * @cap: the v4l2_dv_timings_cap capabilities.
  84 * @pclock_delta: maximum delta between t->pixelclock and the timing struct
  85 *              under consideration.
  86 * @fnc: callback to check if a given timings struct is OK. May be NULL.
  87 * @fnc_handle: a handle that is passed on to @fnc.
  88 *
  89 * This function tries to map the given timings to an entry in the
  90 * full list of possible CEA-861 and DMT timings, filtering out any timings
  91 * that are not supported based on the hardware capabilities and the callback
  92 * function (if non-NULL).
  93 *
  94 * On success it will fill in @t with the found timings and it returns true.
  95 * On failure it will return false.
  96 */
  97bool v4l2_find_dv_timings_cap(struct v4l2_dv_timings *t,
  98                              const struct v4l2_dv_timings_cap *cap,
  99                              unsigned pclock_delta,
 100                              v4l2_check_dv_timings_fnc fnc,
 101                              void *fnc_handle);
 102
 103/**
 104 * v4l2_match_dv_timings() - do two timings match?
 105 *
 106 * @measured:     the measured timings data.
 107 * @standard:     the timings according to the standard.
 108 * @pclock_delta: maximum delta in Hz between standard->pixelclock and
 109 *              the measured timings.
 110 * @match_reduced_fps: if true, then fail if V4L2_DV_FL_REDUCED_FPS does not
 111 * match.
 112 *
 113 * Returns true if the two timings match, returns false otherwise.
 114 */
 115bool v4l2_match_dv_timings(const struct v4l2_dv_timings *measured,
 116                           const struct v4l2_dv_timings *standard,
 117                           unsigned pclock_delta, bool match_reduced_fps);
 118
 119/**
 120 * v4l2_print_dv_timings() - log the contents of a dv_timings struct
 121 * @dev_prefix:device prefix for each log line.
 122 * @prefix:     additional prefix for each log line, may be NULL.
 123 * @t:          the timings data.
 124 * @detailed:   if true, give a detailed log.
 125 */
 126void v4l2_print_dv_timings(const char *dev_prefix, const char *prefix,
 127                           const struct v4l2_dv_timings *t, bool detailed);
 128
 129/**
 130 * v4l2_detect_cvt - detect if the given timings follow the CVT standard
 131 *
 132 * @frame_height: the total height of the frame (including blanking) in lines.
 133 * @hfreq: the horizontal frequency in Hz.
 134 * @vsync: the height of the vertical sync in lines.
 135 * @active_width: active width of image (does not include blanking). This
 136 * information is needed only in case of version 2 of reduced blanking.
 137 * In other cases, this parameter does not have any effect on timings.
 138 * @polarities: the horizontal and vertical polarities (same as struct
 139 *              v4l2_bt_timings polarities).
 140 * @interlaced: if this flag is true, it indicates interlaced format
 141 * @fmt: the resulting timings.
 142 *
 143 * This function will attempt to detect if the given values correspond to a
 144 * valid CVT format. If so, then it will return true, and fmt will be filled
 145 * in with the found CVT timings.
 146 */
 147bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
 148                unsigned active_width, u32 polarities, bool interlaced,
 149                struct v4l2_dv_timings *fmt);
 150
 151/**
 152 * v4l2_detect_gtf - detect if the given timings follow the GTF standard
 153 *
 154 * @frame_height: the total height of the frame (including blanking) in lines.
 155 * @hfreq: the horizontal frequency in Hz.
 156 * @vsync: the height of the vertical sync in lines.
 157 * @polarities: the horizontal and vertical polarities (same as struct
 158 *              v4l2_bt_timings polarities).
 159 * @interlaced: if this flag is true, it indicates interlaced format
 160 * @aspect: preferred aspect ratio. GTF has no method of determining the
 161 *              aspect ratio in order to derive the image width from the
 162 *              image height, so it has to be passed explicitly. Usually
 163 *              the native screen aspect ratio is used for this. If it
 164 *              is not filled in correctly, then 16:9 will be assumed.
 165 * @fmt: the resulting timings.
 166 *
 167 * This function will attempt to detect if the given values correspond to a
 168 * valid GTF format. If so, then it will return true, and fmt will be filled
 169 * in with the found GTF timings.
 170 */
 171bool v4l2_detect_gtf(unsigned frame_height, unsigned hfreq, unsigned vsync,
 172                u32 polarities, bool interlaced, struct v4l2_fract aspect,
 173                struct v4l2_dv_timings *fmt);
 174
 175/**
 176 * v4l2_calc_aspect_ratio - calculate the aspect ratio based on bytes
 177 *      0x15 and 0x16 from the EDID.
 178 *
 179 * @hor_landscape: byte 0x15 from the EDID.
 180 * @vert_portrait: byte 0x16 from the EDID.
 181 *
 182 * Determines the aspect ratio from the EDID.
 183 * See VESA Enhanced EDID standard, release A, rev 2, section 3.6.2:
 184 * "Horizontal and Vertical Screen Size or Aspect Ratio"
 185 */
 186struct v4l2_fract v4l2_calc_aspect_ratio(u8 hor_landscape, u8 vert_portrait);
 187
 188/*
 189 * reduce_fps - check if conditions for reduced fps are true.
 190 * bt - v4l2 timing structure
 191 * For different timings reduced fps is allowed if following conditions
 192 * are met -
 193 * For CVT timings: if reduced blanking v2 (vsync == 8) is true.
 194 * For CEA861 timings: if V4L2_DV_FL_CAN_REDUCE_FPS flag is true.
 195 */
 196static inline  bool can_reduce_fps(struct v4l2_bt_timings *bt)
 197{
 198        if ((bt->standards & V4L2_DV_BT_STD_CVT) && (bt->vsync == 8))
 199                return true;
 200
 201        if ((bt->standards & V4L2_DV_BT_STD_CEA861) &&
 202            (bt->flags & V4L2_DV_FL_CAN_REDUCE_FPS))
 203                return true;
 204
 205        return false;
 206}
 207
 208
 209#endif
 210