diff options
Diffstat (limited to 'sound/firewire')
| -rw-r--r-- | sound/firewire/fireface/ff-protocol-former.c | 23 | ||||
| -rw-r--r-- | sound/firewire/fireface/ff-protocol-latter.c | 18 | ||||
| -rw-r--r-- | sound/firewire/fireface/ff-transaction.c | 36 |
3 files changed, 48 insertions, 29 deletions
diff --git a/sound/firewire/fireface/ff-protocol-former.c b/sound/firewire/fireface/ff-protocol-former.c index e0acf40a02ee..8d1c2c6e907b 100644 --- a/sound/firewire/fireface/ff-protocol-former.c +++ b/sound/firewire/fireface/ff-protocol-former.c @@ -396,6 +396,10 @@ static void ff800_finish_session(struct snd_ff *ff) FF800_ISOC_COMM_STOP, ®, sizeof(reg), 0); } +// Fireface 800 doesn't allow drivers to register lower 4 bytes of destination +// address. +// A write transaction to clear registered higher 4 bytes of destination address +// has an effect to suppress asynchronous transaction from device. static void ff800_handle_midi_msg(struct snd_ff *ff, unsigned int offset, __le32 *buf, size_t length) { @@ -525,6 +529,25 @@ static void ff400_finish_session(struct snd_ff *ff) FF400_ISOC_COMM_STOP, ®, sizeof(reg), 0); } +// For Fireface 400, lower 4 bytes of destination address is configured by bit +// flag in quadlet register (little endian) at 0x'0000'801'0051c. Drivers can +// select one of 4 options: +// +// bit flags: offset of destination address +// - 0x04000000: 0x'....'....'0000'0000 +// - 0x08000000: 0x'....'....'0000'0080 +// - 0x10000000: 0x'....'....'0000'0100 +// - 0x20000000: 0x'....'....'0000'0180 +// +// Drivers can suppress the device to transfer asynchronous transactions by +// using below 2 bits. +// - 0x01000000: suppress transmission +// - 0x02000000: suppress transmission +// +// Actually, the register is write-only and includes the other options such as +// input attenuation. This driver allocates destination address with '0000'0000 +// in its lower offset and expects userspace application to configure the +// register for it. static void ff400_handle_midi_msg(struct snd_ff *ff, unsigned int offset, __le32 *buf, size_t length) { 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) { diff --git a/sound/firewire/fireface/ff-transaction.c b/sound/firewire/fireface/ff-transaction.c index d8a8b01b39a1..0d6ad19363b8 100644 --- a/sound/firewire/fireface/ff-transaction.c +++ b/sound/firewire/fireface/ff-transaction.c @@ -165,35 +165,13 @@ static int allocate_own_address(struct snd_ff *ff, int i) return err; } -/* - * Controllers are allowed to register higher 4 bytes of address to receive - * the transactions. Different models have different registers for this purpose; - * e.g. 0x'0000'8010'03f4 for Fireface 400. - * The controllers are not allowed to register lower 4 bytes of the address. - * They are forced to select one of 4 options for the part of address by writing - * corresponding bits to 0x'0000'8010'051f. - * - * The 3rd-6th bits of this register are flags to indicate lower 4 bytes of - * address to which the device transferrs the transactions. In short: - * - 0x20: 0x'....'....'0000'0180 - * - 0x10: 0x'....'....'0000'0100 - * - 0x08: 0x'....'....'0000'0080 - * - 0x04: 0x'....'....'0000'0000 - * - * This driver configure 0x'....'....'0000'0000 to receive MIDI messages from - * units. The 3rd bit of the register should be configured, however this driver - * deligates this task to userspace applications due to a restriction that this - * register is write-only and the other bits have own effects. - * - * Unlike Fireface 800, Fireface 400 cancels transferring asynchronous - * transactions when the 1st and 2nd of the register stand. These two bits have - * the same effect. - * - 0x02, 0x01: cancel transferring - * - * On the other hand, the bits have no effect on Fireface 800. This model - * cancels asynchronous transactions when the higher 4 bytes of address is - * overwritten with zero. - */ +// Controllers are allowed to register higher 4 bytes of destination address to +// receive asynchronous transactions for MIDI messages, while the way to +// register lower 4 bytes of address is different depending on protocols. For +// details, please refer to comments in protocol implementations. +// +// This driver expects userspace applications to configure registers for the +// lower address because in most cases such registers has the other settings. int snd_ff_transaction_reregister(struct snd_ff *ff) { struct fw_card *fw_card = fw_parent_device(ff->unit)->card; |