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
sad_max_channels(const u8 * sad)20 static unsigned int sad_max_channels(const u8 *sad)
21 {
22 return 1 + (sad[0] & 7);
23 }
24
eld_limit_rates(struct snd_pcm_hw_params * params,struct snd_pcm_hw_rule * rule)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
eld_limit_channels(struct snd_pcm_hw_params * params,struct snd_pcm_hw_rule * rule)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
snd_pcm_hw_constraint_eld(struct snd_pcm_runtime * runtime,void * eld)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
