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https://github.com/edk2-porting/linux-next.git
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838d1631b7
Add a helper for the EDID like data structure, which is typically passed from a HDMI adapter to its associated audio driver. This informs the audio driver of the capabilities of the attached HDMI sink. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Reviewed-by: Mark Brown <broonie@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
100 lines
2.4 KiB
C
100 lines
2.4 KiB
C
/*
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* PCM DRM helpers
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/export.h>
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#include <drm/drm_edid.h>
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#include <sound/pcm.h>
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#include <sound/pcm_drm_eld.h>
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static const unsigned int eld_rates[] = {
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32000,
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44100,
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48000,
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88200,
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96000,
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176400,
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192000,
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};
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static unsigned int sad_max_channels(const u8 *sad)
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{
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return 1 + (sad[0] & 7);
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}
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static int eld_limit_rates(struct snd_pcm_hw_params *params,
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struct snd_pcm_hw_rule *rule)
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{
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struct snd_interval *r = hw_param_interval(params, rule->var);
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struct snd_interval *c;
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unsigned int rate_mask = 7, i;
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const u8 *sad, *eld = rule->private;
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sad = drm_eld_sad(eld);
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if (sad) {
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c = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
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for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3) {
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unsigned max_channels = sad_max_channels(sad);
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/*
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* Exclude SADs which do not include the
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* requested number of channels.
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*/
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if (c->min <= max_channels)
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rate_mask |= sad[1];
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}
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}
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return snd_interval_list(r, ARRAY_SIZE(eld_rates), eld_rates,
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rate_mask);
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}
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static int eld_limit_channels(struct snd_pcm_hw_params *params,
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struct snd_pcm_hw_rule *rule)
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{
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struct snd_interval *c = hw_param_interval(params, rule->var);
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struct snd_interval *r;
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struct snd_interval t = { .min = 1, .max = 2, .integer = 1, };
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unsigned int i;
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const u8 *sad, *eld = rule->private;
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sad = drm_eld_sad(eld);
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if (sad) {
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unsigned int rate_mask = 0;
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/* Convert the rate interval to a mask */
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r = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
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for (i = 0; i < ARRAY_SIZE(eld_rates); i++)
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if (r->min <= eld_rates[i] && r->max >= eld_rates[i])
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rate_mask |= BIT(i);
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for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3)
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if (rate_mask & sad[1])
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t.max = max(t.max, sad_max_channels(sad));
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}
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return snd_interval_refine(c, &t);
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}
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int snd_pcm_hw_constraint_eld(struct snd_pcm_runtime *runtime, void *eld)
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{
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int ret;
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ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
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eld_limit_rates, eld,
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SNDRV_PCM_HW_PARAM_CHANNELS, -1);
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if (ret < 0)
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return ret;
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ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
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eld_limit_channels, eld,
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SNDRV_PCM_HW_PARAM_RATE, -1);
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return ret;
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}
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EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld);
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