xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

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

Browse Source 
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>
This commit is contained in:
Takashi Sakamoto
2017-05-22 22:22:21 +09:00
committed by Takashi Iwai
parent 665170f731
commit a02cb8f8de
12 changed files with 9 additions and 227 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
sound/firewire/dice/dice-pcm.c
View File

@@ -146,7 +146,6 @@ static int capture_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *hw_params)
{
struct snd_dice *dice = substream->private_data;
struct amdtp_stream *stream = &dice->tx_stream[substream->pcm->device];
int err;
err = snd_pcm_lib_alloc_vmalloc_buffer(substream,
@@ -160,15 +159,12 @@ static int capture_hw_params(struct snd_pcm_substream *substream,
mutex_unlock(&dice->mutex);
}
amdtp_am824_set_pcm_format(stream, params_format(hw_params));
return 0;
}
static int playback_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *hw_params)
{
struct snd_dice *dice = substream->private_data;
struct amdtp_stream *stream = &dice->rx_stream[substream->pcm->device];
int err;
err = snd_pcm_lib_alloc_vmalloc_buffer(substream,
@@ -182,8 +178,6 @@ static int playback_hw_params(struct snd_pcm_substream *substream,
mutex_unlock(&dice->mutex);
}
amdtp_am824_set_pcm_format(stream, params_format(hw_params));
return 0;
}