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ALSA: pcm: add DRM ELD helper

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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>
This commit is contained in:
Russell King 2015-05-09 11:26:42 +01:00 committed by Takashi Iwai
parent b787f68c36
commit 838d1631b7
4 changed files with 109 additions and 0 deletions
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6
include/sound/pcm_drm_eld.h Normal file
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@ -0,0 +1,6 @@
#ifndef __SOUND_PCM_DRM_ELD_H
#define __SOUND_PCM_DRM_ELD_H
int snd_pcm_hw_constraint_eld(struct snd_pcm_runtime *runtime, void *eld);
#endif

3
sound/core/Kconfig
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@ -6,6 +6,9 @@ config SND_PCM
tristate
select SND_TIMER
config SND_PCM_ELD
bool
config SND_DMAENGINE_PCM
tristate

1
sound/core/Makefile
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@ -13,6 +13,7 @@ snd-$(CONFIG_SND_JACK) += jack.o
snd-pcm-y := pcm.o pcm_native.o pcm_lib.o pcm_timer.o pcm_misc.o \
pcm_memory.o memalloc.o
snd-pcm-$(CONFIG_SND_DMA_SGBUF) += sgbuf.o
snd-pcm-$(CONFIG_SND_PCM_ELD) += pcm_drm_eld.o
# for trace-points
CFLAGS_pcm_lib.o := -I$(src)

99
sound/core/pcm_drm_eld.c Normal file
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@ -0,0 +1,99 @@
/*
* PCM DRM helpers
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/export.h>
#include <drm/drm_edid.h>
#include <sound/pcm.h>
#include <sound/pcm_drm_eld.h>
static const unsigned int eld_rates[] = {
32000,
44100,
48000,
88200,
96000,
176400,
192000,
};
static unsigned int sad_max_channels(const u8 *sad)
{
return 1 + (sad[0] & 7);
}
static int eld_limit_rates(struct snd_pcm_hw_params *params,
struct snd_pcm_hw_rule *rule)
{
struct snd_interval *r = hw_param_interval(params, rule->var);
struct snd_interval *c;
unsigned int rate_mask = 7, i;
const u8 *sad, *eld = rule->private;
sad = drm_eld_sad(eld);
if (sad) {
c = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3) {
unsigned max_channels = sad_max_channels(sad);
/*
* Exclude SADs which do not include the
* requested number of channels.
*/
if (c->min <= max_channels)
rate_mask |= sad[1];
}
}
return snd_interval_list(r, ARRAY_SIZE(eld_rates), eld_rates,
rate_mask);
}
static int eld_limit_channels(struct snd_pcm_hw_params *params,
struct snd_pcm_hw_rule *rule)
{
struct snd_interval *c = hw_param_interval(params, rule->var);
struct snd_interval *r;
struct snd_interval t = { .min = 1, .max = 2, .integer = 1, };
unsigned int i;
const u8 *sad, *eld = rule->private;
sad = drm_eld_sad(eld);
if (sad) {
unsigned int rate_mask = 0;
/* Convert the rate interval to a mask */
r = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
for (i = 0; i < ARRAY_SIZE(eld_rates); i++)
if (r->min <= eld_rates[i] && r->max >= eld_rates[i])
rate_mask |= BIT(i);
for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3)
if (rate_mask & sad[1])
t.max = max(t.max, sad_max_channels(sad));
}
return snd_interval_refine(c, &t);
}
int snd_pcm_hw_constraint_eld(struct snd_pcm_runtime *runtime, void *eld)
{
int ret;
ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
eld_limit_rates, eld,
SNDRV_PCM_HW_PARAM_CHANNELS, -1);
if (ret < 0)
return ret;
ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
eld_limit_channels, eld,
SNDRV_PCM_HW_PARAM_RATE, -1);
return ret;
}
EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld);