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-rw-r--r--sound/firewire/amdtp.h24
1 files changed, 22 insertions, 2 deletions
diff --git a/sound/firewire/amdtp.h b/sound/firewire/amdtp.h
index 4823c08196ac..e6e8926275b0 100644
--- a/sound/firewire/amdtp.h
+++ b/sound/firewire/amdtp.h
@@ -23,7 +23,7 @@
* corresponds to the end of event in the packet. Out of IEC 61883.
* @CIP_WRONG_DBS: Only for in-stream. The value of dbs is wrong in in-packets.
* The value of data_block_quadlets is used instead of reported value.
- * @SKIP_DBC_ZERO_CHECK: Only for in-stream. Packets with zero in dbc is
+ * @CIP_SKIP_DBC_ZERO_CHECK: Only for in-stream. Packets with zero in dbc is
* skipped for detecting discontinuity.
* @CIP_SKIP_INIT_DBC_CHECK: Only for in-stream. The value of dbc in first
* packet is not continuous from an initial value.
@@ -43,7 +43,27 @@ enum cip_flags {
};
/**
- * enum cip_sfc - a stream's sample rate
+ * enum cip_sfc - supported Sampling Frequency Codes (SFCs)
+ * @CIP_SFC_32000: 32,000 data blocks
+ * @CIP_SFC_44100: 44,100 data blocks
+ * @CIP_SFC_48000: 48,000 data blocks
+ * @CIP_SFC_88200: 88,200 data blocks
+ * @CIP_SFC_96000: 96,000 data blocks
+ * @CIP_SFC_176400: 176,400 data blocks
+ * @CIP_SFC_192000: 192,000 data blocks
+ * @CIP_SFC_COUNT: the number of supported SFCs
+ *
+ * These values are used to show nominal Sampling Frequency Code in
+ * Format Dependent Field (FDF) of AMDTP packet header. In IEC 61883-6:2002,
+ * this code means the number of events per second. Actually the code
+ * represents the number of data blocks transferred per second in an AMDTP
+ * stream.
+ *
+ * In IEC 61883-6:2005, some extensions were added to support more types of
+ * data such as 'One Bit LInear Audio', therefore the meaning of SFC became
+ * different depending on the types.
+ *
+ * Currently our implementation is compatible with IEC 61883-6:2002.
*/
enum cip_sfc {
CIP_SFC_32000 = 0,