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authorStefan Richter <stefanr@s5r6.in-berlin.de>2010-07-29 20:19:22 +0400
committerStefan Richter <stefanr@s5r6.in-berlin.de>2010-07-30 01:09:18 +0400
commit872e330e38806d835bd6c311c93ab998e2fb9058 (patch)
tree92497ce79b1157761b1aebdb63b8d74f68d42c15 /drivers/firewire/core.h
parentae2a97661482c1d0f1aa41b837da95054d0e9a1b (diff)
downloadlinux-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.h2
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,