Russell King | 838d163 | 2015-05-09 11:26:42 +0100 | [diff] [blame] | 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 | 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 | |
| 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 | 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 | |
| 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); |