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| author | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2010-07-29 20:19:22 +0400 |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2010-07-30 01:09:18 +0400 |
| commit | 872e330e38806d835bd6c311c93ab998e2fb9058 (patch) | |
| tree | 92497ce79b1157761b1aebdb63b8d74f68d42c15 /drivers/firewire/core.h | |
| parent | ae2a97661482c1d0f1aa41b837da95054d0e9a1b (diff) | |
| download | linux-872e330e38806d835bd6c311c93ab998e2fb9058.tar.xz | |
firewire: add isochronous multichannel reception
This adds the DMA context programming and userspace ABI for multichannel
reception, i.e. for listening on multiple channel numbers by means of a
single DMA context.
The use case is reception of more streams than there are IR DMA units
offered by the link layer. This is already implemented by the older
ohci1394 + ieee1394 + raw1394 stack. And as discussed recently on
linux1394-devel, this feature is occasionally used in practice.
The big drawbacks of this mode are that buffer layout and interrupt
generation necessarily differ from single-channel reception: Headers
and trailers are not stripped from packets, packets are not aligned with
buffer chunks, interrupts are per buffer chunk, not per packet.
These drawbacks also cause a rather hefty code footprint to support this
rarely used OHCI-1394 feature. (367 lines added, among them 94 lines of
added userspace ABI documentation.)
This implementation enforces that a multichannel reception context may
only listen to channels to which no single-channel context on the same
link layer is presently listening to. OHCI-1394 would allow to overlay
single-channel contexts by the multi-channel context, but this would be
a departure from the present first-come-first-served policy of IR
context creation.
The implementation is heavily based on an earlier one by Jay Fenlason.
Thanks Jay.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/firewire/core.h')
| -rw-r--r-- | drivers/firewire/core.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h index 28621e44b111..e6239f971be6 100644 --- a/drivers/firewire/core.h +++ b/drivers/firewire/core.h @@ -90,6 +90,8 @@ struct fw_card_driver { int (*start_iso)(struct fw_iso_context *ctx, s32 cycle, u32 sync, u32 tags); + int (*set_iso_channels)(struct fw_iso_context *ctx, u64 *channels); + int (*queue_iso)(struct fw_iso_context *ctx, struct fw_iso_packet *packet, struct fw_iso_buffer *buffer, |