LXR linux/sound/core/pcm_drm

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  PCM DRM helpers
   4 */
   5#include <linux/export.h>
   6#include <drm/drm_edid.h>
   7#include <sound/pcm.h>
   8#include <sound/pcm_drm_eld.h>
   9
  10static const unsigned int eld_rates[] = {
  11        32000,
  12        44100,
  13        48000,
  14        88200,
  15        96000,
  16        176400,
  17        192000,
  18};
  19
  20static unsigned int sad_max_channels(const u8 *sad)
  21{
  22        return 1 + (sad[0] & 7);
  23}
  24
  25static int eld_limit_rates(struct snd_pcm_hw_params *params,
  26                           struct snd_pcm_hw_rule *rule)
  27{
  28        struct snd_interval *r = hw_param_interval(params, rule->var);
  29        const struct snd_interval *c;
  30        unsigned int rate_mask = 7, i;
  31        const u8 *sad, *eld = rule->private;
  32
  33        sad = drm_eld_sad(eld);
  34        if (sad) {
  35                c = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_CHANNELS);
  36
  37                for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3) {
  38                        unsigned max_channels = sad_max_channels(sad);
  39
  40                        /*
  41                         * Exclude SADs which do not include the
  42                         * requested number of channels.
  43                         */
  44                        if (c->min <= max_channels)
  45                                rate_mask |= sad[1];
  46                }
  47        }
  48
  49        return snd_interval_list(r, ARRAY_SIZE(eld_rates), eld_rates,
  50                                 rate_mask);
  51}
  52
  53static int eld_limit_channels(struct snd_pcm_hw_params *params,
  54                              struct snd_pcm_hw_rule *rule)
  55{
  56        struct snd_interval *c = hw_param_interval(params, rule->var);
  57        const struct snd_interval *r;
  58        struct snd_interval t = { .min = 1, .max = 2, .integer = 1, };
  59        unsigned int i;
  60        const u8 *sad, *eld = rule->private;
  61
  62        sad = drm_eld_sad(eld);
  63        if (sad) {
  64                unsigned int rate_mask = 0;
  65
  66                /* Convert the rate interval to a mask */
  67                r = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
  68                for (i = 0; i < ARRAY_SIZE(eld_rates); i++)
  69                        if (r->min <= eld_rates[i] && r->max >= eld_rates[i])
  70                                rate_mask |= BIT(i);
  71
  72                for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3)
  73                        if (rate_mask & sad[1])
  74                                t.max = max(t.max, sad_max_channels(sad));
  75        }
  76
  77        return snd_interval_refine(c, &t);
  78}
  79
  80int snd_pcm_hw_constraint_eld(struct snd_pcm_runtime *runtime, void *eld)
  81{
  82        int ret;
  83
  84        ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
  85                                  eld_limit_rates, eld,
  86                                  SNDRV_PCM_HW_PARAM_CHANNELS, -1);
  87        if (ret < 0)
  88                return ret;
  89
  90        ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
  91                                  eld_limit_channels, eld,
  92                                  SNDRV_PCM_HW_PARAM_RATE, -1);
  93
  94        return ret;
  95}
  96EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld);
  97