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>

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