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Commit f97a0944 authored by Takashi Sakamoto's avatar Takashi Sakamoto Committed by Takashi Iwai
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ALSA: firewire-motu: fix construction of PCM frame for capture direction 



In data blocks of common isochronous packet for MOTU devices, PCM
frames are multiplexed in a shape of '24 bit * 4 Audio Pack', described
in IEC 61883-6. The frames are not aligned to quadlet.

For capture PCM substream, ALSA firewire-motu driver constructs PCM
frames by reading data blocks byte-by-byte. However this operation
includes bug for lower byte of the PCM sample. This brings invalid
content of the PCM samples.

This commit fixes the bug.

Reported-by: default avatarPeter Sjöberg <autopeter@gmail.com>
Cc: <stable@vger.kernel.org> # v4.12+
Fixes: 4641c939 ("ALSA: firewire-motu: add MOTU specific protocol layer")
Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 7dc661bd

sound/firewire/motu/amdtp-motu.c

+3 −1
Original line number Diff line number Diff line
@@ -136,7 +136,9 @@ static void read_pcm_s32(struct amdtp_stream *s, 
		byte = (u8 *)buffer + p->pcm_byte_offset;



		for (c = 0; c < channels; ++c) {

			*dst = (byte[0] << 24) | (byte[1] << 16) | byte[2];

			*dst = (byte[0] << 24) |

			       (byte[1] << 16) |

			       (byte[2] << 8);

			byte += 3;

			dst++;

		}