[PATCH 1/2] ALSA: aloop: Add support for the non-interleaved access mode

[PATCH 1/2] ALSA: aloop: Add support for the non-interleaved access mode

[Ivan Orlov]

The current version of the loopback driver supports interleaved access
mode only. This patch introduces support for the non-interleaved
access mode.

When in the interleaved mode, the 'copy_play_buf' function copies data
from the playback to the capture buffer using one memcpy call. This call
copies samples for multiple, interleaved channels.

In the non-interleaved mode we have multiple channel buffers, so we have
to perform multiple memcpy calls to copy samples channel after channel.

Add new function called 'copy_play_buf_part_n', which copies a part of
each channel buffer from playback to capture. Modify the 'copy_play_buf'
to use the corresponding memory copy function(just memcpy /
copy_play_buf_part_n) depending on the access mode.

Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
---
 sound/drivers/aloop.c | 31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/sound/drivers/aloop.c b/sound/drivers/aloop.c
index a38e602b4fc6..ab116b1fed96 100644
--- a/sound/drivers/aloop.c
+++ b/sound/drivers/aloop.c
@@ -158,6 +158,9 @@ struct loopback_pcm {
 	unsigned long last_jiffies;
 	/* If jiffies timer is used */
 	struct timer_list timer;
+
+	/* size of per channel buffer in case of non-interleaved access */
+	unsigned int channel_buf_n;
 };
 
 static struct platform_device *devices[SNDRV_CARDS];
@@ -335,7 +338,8 @@ static int loopback_check_format(struct loopback_cable *cable, int stream)
 							substream->runtime;
 	check = runtime->format != cruntime->format ||
 		runtime->rate != cruntime->rate ||
-		runtime->channels != cruntime->channels;
+		runtime->channels != cruntime->channels ||
+		runtime->access != cruntime->access;
 	if (!check)
 		return 0;
 	if (stream == SNDRV_PCM_STREAM_CAPTURE) {
@@ -472,6 +476,7 @@ static int loopback_prepare(struct snd_pcm_substream *substream)
 
 	dpcm->buf_pos = 0;
 	dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size);
+	dpcm->channel_buf_n = dpcm->pcm_buffer_size / runtime->channels;
 	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
 		/* clear capture buffer */
 		dpcm->silent_size = dpcm->pcm_buffer_size;
@@ -522,6 +527,22 @@ static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes)
 	}
 }
 
+static void copy_play_buf_part_n(struct loopback_pcm *play, struct loopback_pcm *capt,
+				 unsigned int size, unsigned int src_off, unsigned int dst_off)
+{
+	unsigned int channels = capt->substream->runtime->channels;
+	unsigned int size_p_ch = size / channels;
+	unsigned int src_off_ch = src_off / channels;
+	unsigned int dst_off_ch = dst_off / channels;
+	int i;
+
+	for (i = 0; i < channels; i++) {
+		memcpy(capt->substream->runtime->dma_area + capt->channel_buf_n * i + dst_off_ch,
+		       play->substream->runtime->dma_area + play->channel_buf_n * i + src_off_ch,
+		       size_p_ch);
+	}
+}
+
 static void copy_play_buf(struct loopback_pcm *play,
 			  struct loopback_pcm *capt,
 			  unsigned int bytes)
@@ -556,7 +577,11 @@ static void copy_play_buf(struct loopback_pcm *play,
 			size = play->pcm_buffer_size - src_off;
 		if (dst_off + size > capt->pcm_buffer_size)
 			size = capt->pcm_buffer_size - dst_off;
-		memcpy(dst + dst_off, src + src_off, size);
+		if (runtime->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED ||
+		    runtime->access == SNDRV_PCM_ACCESS_MMAP_NONINTERLEAVED)
+			copy_play_buf_part_n(play, capt, size, src_off, dst_off);
+		else
+			memcpy(dst + dst_off, src + src_off, size);
 		capt->silent_size = 0;
 		bytes -= size;
 		if (!bytes)
@@ -878,7 +903,7 @@ static const struct snd_pcm_hardware loopback_pcm_hardware =
 {
 	.info =		(SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP |
 			 SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE |
-			 SNDRV_PCM_INFO_RESUME),
+			 SNDRV_PCM_INFO_RESUME | SNDRV_PCM_INFO_NONINTERLEAVED),
 	.formats =	(SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
 			 SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |
 			 SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE |
-- 
2.34.1

[PATCH 2/2] ALSA: aloop: Add control element for getting the access mode

[Ivan Orlov]

Add new control element 'PCM Slave Access Mode' which shows the access
mode (interleaved/non-interleaved) for the PCM playing device. Add
corresponding control change notification calls.

Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
---
 sound/drivers/aloop.c | 45 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/sound/drivers/aloop.c b/sound/drivers/aloop.c
index ab116b1fed96..e87dc67f33c6 100644
--- a/sound/drivers/aloop.c
+++ b/sound/drivers/aloop.c
@@ -119,11 +119,13 @@ struct loopback_setup {
 	unsigned int rate_shift;
 	snd_pcm_format_t format;
 	unsigned int rate;
+	snd_pcm_access_t access;
 	unsigned int channels;
 	struct snd_ctl_elem_id active_id;
 	struct snd_ctl_elem_id format_id;
 	struct snd_ctl_elem_id rate_id;
 	struct snd_ctl_elem_id channels_id;
+	struct snd_ctl_elem_id access_id;
 };
 
 struct loopback {
@@ -367,6 +369,11 @@ static int loopback_check_format(struct loopback_cable *cable, int stream)
 							&setup->channels_id);
 			setup->channels = runtime->channels;
 		}
+		if (setup->access != runtime->access) {
+			snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
+							&setup->access_id);
+			setup->access = runtime->access;
+		}
 	}
 	return 0;
 }
@@ -1520,6 +1527,30 @@ static int loopback_channels_get(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
+static int loopback_access_info(struct snd_kcontrol *kcontrol,
+				struct snd_ctl_elem_info *uinfo)
+{
+	const char * const texts[] = {"Interleaved", "Non-interleaved"};
+
+	return snd_ctl_enum_info(uinfo, 1, ARRAY_SIZE(texts), texts);
+}
+
+static int loopback_access_get(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *ucontrol)
+{
+	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
+	snd_pcm_access_t access;
+
+	mutex_lock(&loopback->cable_lock);
+	access = loopback->setup[kcontrol->id.subdevice][kcontrol->id.device].access;
+
+	ucontrol->value.enumerated.item[0] = access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED ||
+					     access == SNDRV_PCM_ACCESS_MMAP_NONINTERLEAVED;
+
+	mutex_unlock(&loopback->cable_lock);
+	return 0;
+}
+
 static const struct snd_kcontrol_new loopback_controls[]  = {
 {
 	.iface =        SNDRV_CTL_ELEM_IFACE_PCM,
@@ -1566,7 +1597,15 @@ static const struct snd_kcontrol_new loopback_controls[]  = {
 	.name =         "PCM Slave Channels",
 	.info =         loopback_channels_info,
 	.get =          loopback_channels_get
-}
+},
+#define ACCESS_IDX 6
+{
+	.access =	SNDRV_CTL_ELEM_ACCESS_READ,
+	.iface =	SNDRV_CTL_ELEM_IFACE_PCM,
+	.name =		"PCM Slave Access Mode",
+	.info =		loopback_access_info,
+	.get =		loopback_access_get,
+},
 };
 
 static int loopback_mixer_new(struct loopback *loopback, int notify)
@@ -1587,6 +1626,7 @@ static int loopback_mixer_new(struct loopback *loopback, int notify)
 			setup->notify = notify;
 			setup->rate_shift = NO_PITCH;
 			setup->format = SNDRV_PCM_FORMAT_S16_LE;
+			setup->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
 			setup->rate = 48000;
 			setup->channels = 2;
 			for (idx = 0; idx < ARRAY_SIZE(loopback_controls);
@@ -1618,6 +1658,9 @@ static int loopback_mixer_new(struct loopback *loopback, int notify)
 				case CHANNELS_IDX:
 					setup->channels_id = kctl->id;
 					break;
+				case ACCESS_IDX:
+					setup->access_id = kctl->id;
+					break;
 				default:
 					break;
 				}
-- 
2.34.1

Re: [PATCH 1/2] ALSA: aloop: Add support for the non-interleaved access mode

[Jaroslav Kysela]

On 27. 09. 23 13:35, Ivan Orlov wrote:
> The current version of the loopback driver supports interleaved access
> mode only. This patch introduces support for the non-interleaved
> access mode.
> 
> When in the interleaved mode, the 'copy_play_buf' function copies data
> from the playback to the capture buffer using one memcpy call. This call
> copies samples for multiple, interleaved channels.
> 
> In the non-interleaved mode we have multiple channel buffers, so we have
> to perform multiple memcpy calls to copy samples channel after channel.
> 
> Add new function called 'copy_play_buf_part_n', which copies a part of
> each channel buffer from playback to capture. Modify the 'copy_play_buf'
> to use the corresponding memory copy function(just memcpy /
> copy_play_buf_part_n) depending on the access mode.
> 
> Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>

Nice extension. Thank you.

> +static void copy_play_buf_part_n(struct loopback_pcm *play, struct loopback_pcm *capt,
> +				 unsigned int size, unsigned int src_off, unsigned int dst_off)

I would probably prefer to have dst,src,size arguments to follow memcpy, but 
it's really nitpicking.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>

					Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

Re: [PATCH 2/2] ALSA: aloop: Add control element for getting the access mode

[Jaroslav Kysela]

On 27. 09. 23 13:35, Ivan Orlov wrote:
> Add new control element 'PCM Slave Access Mode' which shows the access
> mode (interleaved/non-interleaved) for the PCM playing device. Add
> corresponding control change notification calls.
> 
> Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>

Reviewed-by: Jaroslav Kysela <perex@perex.cz>

						Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

Re: [PATCH 1/2] ALSA: aloop: Add support for the non-interleaved access mode

[Takashi Iwai]

On Wed, 27 Sep 2023 13:35:54 +0200,
Ivan Orlov wrote:
> 
> The current version of the loopback driver supports interleaved access
> mode only. This patch introduces support for the non-interleaved
> access mode.
> 
> When in the interleaved mode, the 'copy_play_buf' function copies data
> from the playback to the capture buffer using one memcpy call. This call
> copies samples for multiple, interleaved channels.
> 
> In the non-interleaved mode we have multiple channel buffers, so we have
> to perform multiple memcpy calls to copy samples channel after channel.
> 
> Add new function called 'copy_play_buf_part_n', which copies a part of
> each channel buffer from playback to capture. Modify the 'copy_play_buf'
> to use the corresponding memory copy function(just memcpy /
> copy_play_buf_part_n) depending on the access mode.
> 
> Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>

Sorry for the late reaction, as I've been (still) off since the last
week.

Now applied both patches.  Thanks.


Takashi

Re: [PATCH 1/2] ALSA: aloop: Add support for the non-interleaved access mode

[Ivan Orlov]

On 10/5/23 08:23, Jaroslav Kysela wrote:
> On 27. 09. 23 13:35, Ivan Orlov wrote:
>> The current version of the loopback driver supports interleaved access
>> mode only. This patch introduces support for the non-interleaved
>> access mode.
>>
>> When in the interleaved mode, the 'copy_play_buf' function copies data
>> from the playback to the capture buffer using one memcpy call. This call
>> copies samples for multiple, interleaved channels.
>>
>> In the non-interleaved mode we have multiple channel buffers, so we have
>> to perform multiple memcpy calls to copy samples channel after channel.
>>
>> Add new function called 'copy_play_buf_part_n', which copies a part of
>> each channel buffer from playback to capture. Modify the 'copy_play_buf'
>> to use the corresponding memory copy function(just memcpy /
>> copy_play_buf_part_n) depending on the access mode.
>>
>> Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
> 
> Nice extension. Thank you.
> 
>> +static void copy_play_buf_part_n(struct loopback_pcm *play, struct 
>> loopback_pcm *capt,
>> +                 unsigned int size, unsigned int src_off, unsigned 
>> int dst_off)
> 
> I would probably prefer to have dst,src,size arguments to follow memcpy, 
> but it's really nitpicking.
> 
> Reviewed-by: Jaroslav Kysela <perex@perex.cz>
> 
>                      Jaroslav
> 

Hi Jaroslav,

Thank you for the review!

I agree that parameters similar to the memcpy would look better than 
that, I'll keep it in mind when I send the next patch :)

--
Kind regards,
Ivan Orlov

Re: [PATCH 1/2] ALSA: aloop: Add support for the non-interleaved access mode

[Ivan Orlov]

On 10/6/23 09:52, Takashi Iwai wrote:
> On Wed, 27 Sep 2023 13:35:54 +0200,
> Ivan Orlov wrote:
>>
>> The current version of the loopback driver supports interleaved access
>> mode only. This patch introduces support for the non-interleaved
>> access mode.
>>
>> When in the interleaved mode, the 'copy_play_buf' function copies data
>> from the playback to the capture buffer using one memcpy call. This call
>> copies samples for multiple, interleaved channels.
>>
>> In the non-interleaved mode we have multiple channel buffers, so we have
>> to perform multiple memcpy calls to copy samples channel after channel.
>>
>> Add new function called 'copy_play_buf_part_n', which copies a part of
>> each channel buffer from playback to capture. Modify the 'copy_play_buf'
>> to use the corresponding memory copy function(just memcpy /
>> copy_play_buf_part_n) depending on the access mode.
>>
>> Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
> 
> Sorry for the late reaction, as I've been (still) off since the last
> week.
> 
> Now applied both patches.  Thanks.
> 

Hi Takashi,

No worries and thank you for applying both patches :)

--
Kind regards,
Ivan Orlov