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 10 static const unsigned int eld_rates[] = { 11 32000, 12 44100, 13 48000, 14 88200, 15 96000, 16 176400, 17 192000, 18 }; 19 20 static unsigned int sad_max_channels(const u8 *sad) 21 { 22 return 1 + (sad[0] & 7); 23 } 24 25 static 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 53 static 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 80 int 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 } 96 EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld); 97