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>
diff --git a/sound/firewire/amdtp-am824.c b/sound/firewire/amdtp-am824.c
index da4b643..f5edcbf 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
