ALSA: firewire: remove support for 16 bit PCM samples in playback substream

In IEC 61883-6, AM824 is described as format of data block. In this
format, one data block consists of several data channels, which is aligned
to 32 bit. One data channel has 8 bit label field and 24 bit data field.
PCM frames are transferred in Multi Bit Linear Audio (MBLA) data channel.
This channel can include 16/20/24 bit PCM sample.

As long as I know, models which support IEC 61883-1/6 doesn't allow to
switch bit length of PCM sample in MBLA data channel. They always
transmit/receive PCM frames of 24 bit length. This can be seen for the
other models which support protocols similar to IEC 61883-1/6.

On the other hand, current drivers for these protocols supports 16 bit
length PCM sample in playback substream. In this case, PCM sample is put
into the MBLA data channel with 8 bit padding in LSB side. Although 16
bit PCM sample is major because it's in CD format, this doesn't represent
device capability as is.

This commit removes support for 16 bit PCM samples in playback substream.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 2 insertions, 60 deletions

diff --git a/sound/firewire/tascam/amdtp-tascam.c b/sound/firewire/tascam/amdtp-tascam.c
index 9dd0fcc..6aff1fc 100644
--- a/sound/firewire/tascam/amdtp-tascam.c
+++ b/sound/firewire/tascam/amdtp-tascam.c
@@ -14,10 +14,6 @@
 
 struct amdtp_tscm {
 	unsigned int pcm_channels;
-
-	void (*transfer_samples)(struct amdtp_stream *s,
-				 struct snd_pcm_substream *pcm,
-				 __be32 *buffer, unsigned int frames);
 };
 
 int amdtp_tscm_set_parameters(struct amdtp_stream *s, unsigned int rate)
@@ -62,31 +58,6 @@ static void write_pcm_s32(struct amdtp_stream *s,
 	}
 }
 
-static void write_pcm_s16(struct amdtp_stream *s,
-			  struct snd_pcm_substream *pcm,
-			  __be32 *buffer, unsigned int frames)
-{
-	struct amdtp_tscm *p = s->protocol;
-	struct snd_pcm_runtime *runtime = pcm->runtime;
-	unsigned int channels, remaining_frames, i, c;
-	const u16 *src;
-
-	channels = p->pcm_channels;
-	src = (void *)runtime->dma_area +
-			frames_to_bytes(runtime, s->pcm_buffer_pointer);
-	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;
-
-	for (i = 0; i < frames; ++i) {
-		for (c = 0; c < channels; ++c) {
-			buffer[c] = cpu_to_be32(*src << 16);
-			src++;
-		}
-		buffer += s->data_block_quadlets;
-		if (--remaining_frames == 0)
-			src = (void *)runtime->dma_area;
-	}
-}
-
 static void read_pcm_s32(struct amdtp_stream *s,
 			 struct snd_pcm_substream *pcm,
 			 __be32 *buffer, unsigned int frames)
@@ -146,44 +117,16 @@ int amdtp_tscm_add_pcm_hw_constraints(struct amdtp_stream *s,
 	return amdtp_stream_add_pcm_hw_constraints(s, runtime);
 }
 
-void amdtp_tscm_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format)
-{
-	struct amdtp_tscm *p = s->protocol;
-
-	if (WARN_ON(amdtp_stream_pcm_running(s)))
-		return;
-
-	switch (format) {
-	default:
-		WARN_ON(1);
-		/* fall through */
-	case SNDRV_PCM_FORMAT_S16:
-		if (s->direction == AMDTP_OUT_STREAM) {
-			p->transfer_samples = write_pcm_s16;
-			break;
-		}
-		WARN_ON(1);
-		/* fall through */
-	case SNDRV_PCM_FORMAT_S32:
-		if (s->direction == AMDTP_OUT_STREAM)
-			p->transfer_samples = write_pcm_s32;
-		else
-			p->transfer_samples = read_pcm_s32;
-		break;
-	}
-}
-
 static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
 					   __be32 *buffer,
 					   unsigned int data_blocks,
 					   unsigned int *syt)
 {
-	struct amdtp_tscm *p = (struct amdtp_tscm *)s->protocol;
 	struct snd_pcm_substream *pcm;
 
 	pcm = ACCESS_ONCE(s->pcm);
 	if (data_blocks > 0 && pcm)
-		p->transfer_samples(s, pcm, buffer, data_blocks);
+		read_pcm_s32(s, pcm, buffer, data_blocks);
 
 	/* A place holder for control messages. */
 
@@ -195,7 +138,6 @@ static unsigned int process_rx_data_blocks(struct amdtp_stream *s,
 					   unsigned int data_blocks,
 					   unsigned int *syt)
 {
-	struct amdtp_tscm *p = (struct amdtp_tscm *)s->protocol;
 	struct snd_pcm_substream *pcm;
 
 	/* This field is not used. */
@@ -203,7 +145,7 @@ static unsigned int process_rx_data_blocks(struct amdtp_stream *s,
 
 	pcm = ACCESS_ONCE(s->pcm);
 	if (pcm)
-		p->transfer_samples(s, pcm, buffer, data_blocks);
+		write_pcm_s32(s, pcm, buffer, data_blocks);
 	else
 		write_pcm_silence(s, buffer, data_blocks);