diff options
Diffstat (limited to 'sound/firewire/fireface/ff-protocol-latter.c')
| -rw-r--r-- | sound/firewire/fireface/ff-protocol-latter.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/sound/firewire/fireface/ff-protocol-latter.c b/sound/firewire/fireface/ff-protocol-latter.c index 817af4447349..0fbc1950327f 100644 --- a/sound/firewire/fireface/ff-protocol-latter.c +++ b/sound/firewire/fireface/ff-protocol-latter.c @@ -266,6 +266,24 @@ static void latter_dump_status(struct snd_ff *ff, struct snd_info_buffer *buffer // NOTE: transactions are transferred within 0x00-0x7f in allocated range of // address. This seems to be for check of discontinuity in receiver side. +// +// Like Fireface 400, drivers can select one of 4 options for lower 4 bytes of +// destination address by bit flags in quadlet register (little endian) at +// 0x'ffff'0000'0014: +// +// bit flags: offset of destination address +// - 0x00002000: 0x'....'....'0000'0000 +// - 0x00004000: 0x'....'....'0000'0080 +// - 0x00008000: 0x'....'....'0000'0100 +// - 0x00010000: 0x'....'....'0000'0180 +// +// Drivers can suppress the device to transfer asynchronous transactions by +// clear these bit flags. +// +// Actually, the register is write-only and includes the other settings such as +// input attenuation. This driver allocates for the first option +// (0x'....'....'0000'0000) and expects userspace application to configure the +// register for it. static void latter_handle_midi_msg(struct snd_ff *ff, unsigned int offset, __le32 *buf, size_t length) { |