LXR linux/sound/core/pcm_drm

   1/*
   2 *  PCM DRM helpers
   3 *
   4 *   This program is free software; you can redistribute it and/or modify
   5 *   it under the terms of the GNU General Public License version 2 as
   6 *   published by the Free Software Foundation.
   7 */
   8#include <linux/export.h>
   9#include <drm/drm_edid.h>
  10#include <sound/pcm.h>
  11#include <sound/pcm_drm_eld.h>
  12
  13static const unsigned int eld_rates[] = {
  14        32000,
  15        44100,
  16        48000,
  17        88200,
  18        96000,
  19        176400,
  20        192000,
  21};
  22
  23static unsigned int sad_max_channels(const u8 *sad)
  24{
  25        return 1 + (sad[0] & 7);
  26}
  27
  28static int eld_limit_rates(struct snd_pcm_hw_params *params,
  29                           struct snd_pcm_hw_rule *rule)
  30{
  31        struct snd_interval *r = hw_param_interval(params, rule->var);
  32        struct snd_interval *c;
  33        unsigned int rate_mask = 7, i;
  34        const u8 *sad, *eld = rule->private;
  35
  36        sad = drm_eld_sad(eld);
  37        if (sad) {
  38                c = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
  39
  40                for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3) {
  41                        unsigned max_channels = sad_max_channels(sad);
  42
  43                        /*
  44                         * Exclude SADs which do not include the
  45                         * requested number of channels.
  46                         */
  47                        if (c->min <= max_channels)
  48                                rate_mask |= sad[1];
  49                }
  50        }
  51
  52        return snd_interval_list(r, ARRAY_SIZE(eld_rates), eld_rates,
  53                                 rate_mask);
  54}
  55
  56static int eld_limit_channels(struct snd_pcm_hw_params *params,
  57                              struct snd_pcm_hw_rule *rule)
  58{
  59        struct snd_interval *c = hw_param_interval(params, rule->var);
  60        struct snd_interval *r;
  61        struct snd_interval t = { .min = 1, .max = 2, .integer = 1, };
  62        unsigned int i;
  63        const u8 *sad, *eld = rule->private;
  64
  65        sad = drm_eld_sad(eld);
  66        if (sad) {
  67                unsigned int rate_mask = 0;
  68
  69                /* Convert the rate interval to a mask */
  70                r = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
  71                for (i = 0; i < ARRAY_SIZE(eld_rates); i++)
  72                        if (r->min <= eld_rates[i] && r->max >= eld_rates[i])
  73                                rate_mask |= BIT(i);
  74
  75                for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3)
  76                        if (rate_mask & sad[1])
  77                                t.max = max(t.max, sad_max_channels(sad));
  78        }
  79
  80        return snd_interval_refine(c, &t);
  81}
  82
  83int snd_pcm_hw_constraint_eld(struct snd_pcm_runtime *runtime, void *eld)
  84{
  85        int ret;
  86
  87        ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
  88                                  eld_limit_rates, eld,
  89                                  SNDRV_PCM_HW_PARAM_CHANNELS, -1);
  90        if (ret < 0)
  91                return ret;
  92
  93        ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
  94                                  eld_limit_channels, eld,
  95                                  SNDRV_PCM_HW_PARAM_RATE, -1);
  96
  97        return ret;
  98}
  99EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld);
 100