ALSA: firewire-motu: fix construction of PCM frame for capture direction
authorTakashi Sakamoto <o-takashi@sakamocchi.jp>
Tue, 26 Feb 2019 04:38:37 +0000 (13:38 +0900)
committerTakashi Iwai <tiwai@suse.de>
Tue, 26 Feb 2019 06:11:40 +0000 (07:11 +0100)
commitf97a0944a72b26a2bece72516294e112a890f98a
treeff5aa5f7bd785b85df3c16128320b32af8c8eb63
parent7dc661bd8d3261053b69e4e2d0050cd1ee540fc1
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: Peter Sjöberg <autopeter@gmail.com>
Cc: <stable@vger.kernel.org> # v4.12+
Fixes: 4641c9394010 ("ALSA: firewire-motu: add MOTU specific protocol layer")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
sound/firewire/motu/amdtp-motu.c