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 13 static const unsigned int eld_rates[] = { 14 32000, 15 44100, 16 48000, 17 88200, 18 96000, 19 176400, 20 192000, 21 }; 22 23 static unsigned int sad_max_channels(const u8 *sad) 24 { 25 return 1 + (sad[0] & 7); 26 } 27 28 static 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 const 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_c(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 56 static 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 const 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_c(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 83 int 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 } 99 EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld); 100