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authorTakashi Sakamoto <o-takashi@sakamocchi.jp>2015-09-19 04:21:56 +0200
committerTakashi Iwai <tiwai@suse.de>2015-09-29 12:48:02 +0200
commit51c29fd21389d9995a8a18a91eeb8dd1220a2119 (patch)
treebc45c96ca22ad4eb7754da35d99a5394ed831a61 /sound/firewire/amdtp-am824.c
parentALSA: firewire-lib: add data block processing layer for AM824 format (diff)
downloadlinux-51c29fd21389d9995a8a18a91eeb8dd1220a2119.tar.xz
linux-51c29fd21389d9995a8a18a91eeb8dd1220a2119.zip
ALSA: firewire-lib: rename parameter setting function for AM824 with FDF field
The value of FDF field in CIP header is protocol-dependent. Thus, it's better to allow data block processing layer to decide the value in any timing. In AM824 data format, the value of FDF field in CIP header indicates N-flag and Nominal Sampling Frequency Code (sfc). The N-flag is for switching 'Clock-based rate control mode' and 'Command-based rate control mode'. In our implementation, 'Clock-based rate control mode' is just supported. Therefore, When sampling transfer frequency is decided, then the FDF can be set. This commit replaces 'amdtp_stream_set_parameters' with 'amdtp_am824_set_parameters' to set the FDF. This is the same timing to decide the ration between the number of data blocks and the number of PCM frames. Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/firewire/amdtp-am824.c')
-rw-r--r--sound/firewire/amdtp-am824.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/sound/firewire/amdtp-am824.c b/sound/firewire/amdtp-am824.c
index da4b643eff40..f5edcbfa3157 100644
--- a/sound/firewire/amdtp-am824.c
+++ b/sound/firewire/amdtp-am824.c
@@ -10,6 +10,48 @@
#define CIP_FMT_AM 0x10
+/* "Clock-based rate control mode" is just supported. */
+#define AMDTP_FDF_AM824 0x00
+
+/**
+ * amdtp_am824_set_parameters - set stream parameters
+ * @s: the AMDTP stream to configure
+ * @rate: the sample rate
+ * @pcm_channels: the number of PCM samples in each data block, to be encoded
+ * as AM824 multi-bit linear audio
+ * @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
+ * @double_pcm_frames: one data block transfers two PCM frames
+ *
+ * The parameters must be set before the stream is started, and must not be
+ * changed while the stream is running.
+ */
+int amdtp_am824_set_parameters(struct amdtp_stream *s, unsigned int rate,
+ unsigned int pcm_channels,
+ unsigned int midi_ports,
+ bool double_pcm_frames)
+{
+ int err;
+
+ err = amdtp_stream_set_parameters(s, rate, pcm_channels, midi_ports);
+ if (err < 0)
+ return err;
+
+ s->fdf = AMDTP_FDF_AM824 | s->sfc;
+
+ /*
+ * In IEC 61883-6, one data block represents one event. In ALSA, one
+ * event equals to one PCM frame. But Dice has a quirk at higher
+ * sampling rate to transfer two PCM frames in one data block.
+ */
+ if (double_pcm_frames)
+ s->frame_multiplier = 2;
+ else
+ s->frame_multiplier = 1;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);
+
/**
* amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
* data block