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Commit 838d1631 authored by Russell King's avatar Russell King Committed by Takashi Iwai
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ALSA: pcm: add DRM ELD helper 



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: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent b787f68c

include/sound/pcm_drm_eld.h

0 → 100644
+6 −0
Original line number Diff line number Diff line 
#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

sound/core/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -6,6 +6,9 @@ config SND_PCM 
	tristate

	select SND_TIMER



config SND_PCM_ELD

	bool



config SND_DMAENGINE_PCM

	tristate

sound/core/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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)

sound/core/pcm_drm_eld.c

0 → 100644
+99 −0
Original line number Diff line number Diff line 
/*

 *  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);