At Thu, 02 Apr 2015 10:22:06 +0100,
Russell King wrote:
>
> 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 at arm.linux.org.uk>
> ---
> include/sound/pcm_drm_eld.h | 6 +++
> sound/core/Kconfig | 3 ++
> sound/core/Makefile | 1 +
> sound/core/pcm_drm_eld.c | 92
> +++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 102 insertions(+)
> create mode 100644 include/sound/pcm_drm_eld.h
> create mode 100644 sound/core/pcm_drm_eld.c
>
> diff --git a/include/sound/pcm_drm_eld.h b/include/sound/pcm_drm_eld.h
> new file mode 100644
> index 000000000000..93357b25d2e2
> --- /dev/null
> +++ b/include/sound/pcm_drm_eld.h
> @@ -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
IMO, a single line of function declaration can be merged to
sound/pcm.h.
> diff --git a/sound/core/Kconfig b/sound/core/Kconfig
> index 313f22e9d929..b534c8a6046b 100644
> --- a/sound/core/Kconfig
> +++ b/sound/core/Kconfig
> @@ -6,6 +6,9 @@ config SND_PCM
> tristate
> select SND_TIMER
>
> +config SND_PCM_ELD
> + bool
I don't mind much adding this one, but a new Kconfig is always a
question. I'd like to hear other's opinion, too.
> config SND_DMAENGINE_PCM
> tristate
>
> diff --git a/sound/core/Makefile b/sound/core/Makefile
> index 4daf2f58261c..591b49157b4d 100644
> --- a/sound/core/Makefile
> +++ b/sound/core/Makefile
> @@ -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)
> diff --git a/sound/core/pcm_drm_eld.c b/sound/core/pcm_drm_eld.c
> new file mode 100644
> index 000000000000..47d9b60435fe
> --- /dev/null
> +++ b/sound/core/pcm_drm_eld.c
> @@ -0,0 +1,92 @@
> +/*
> + * 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 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 channels = 1 + (sad[0] & 7);
> +
> + /*
> + * Exclude SADs which do not include the
> + * requested number of channels.
> + */
> + if (c->min <= channels)
> + rate_mask |= sad[1];
> + }
> +printk("%s: r %d-%d c %d-%d m %x\n", __func__, r->min, r->max, c->min,
> c->max, rate_mask);
I guess this will be removed in the final version? ;)
> + }
> +
> + 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 *var = hw_param_interval(params, rule->var);
> + 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) {
> + for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3) {
> + switch (sad[0] & 0x78) {
> + case 0x08:
> + t.max = max(t.max, (sad[0] & 7) + 1u);
> + break;
What about the minimal channel?
Ideally, we should either give a list of channel numbers or process
the hw_constraints dynamically to narrow the min/max matching with the
eld.
thanks,
Takashi
> + }
> + }
> + }
> +
> + return snd_interval_refine(var, &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_RATE,
> + 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_CHANNELS,
> + SNDRV_PCM_HW_PARAM_RATE, -1);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld);
> --
> 1.8.3.1
>
