diff options
author | Dan Williams <dan.j.williams@intel.com> | 2009-01-05 17:14:31 -0700 |
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committer | Dan Williams <dan.j.williams@intel.com> | 2009-01-05 18:10:19 -0700 |
commit | 28405d8d9ce05f5bd869ef8b48da5086f9527d73 (patch) | |
tree | f3e68349cc38b4dc0a437455ba9513be78f620ae /drivers/dma/dw_dmac.c | |
parent | fe0bdec68b77020281dc814805edfe594ae89e0f (diff) |
async_tx, dmaengine: document channel allocation and api rework
"Wouldn't it be better if the dmaengine layer made sure it didn't pass
the same channel several times to a client?
I mean, you seem concerned that the memcpy() API should be transparent
and easy to use, but the whole registration interface is just
ridiculously complicated..."
- Haavard
The dmaengine and async_tx registration/allocation interface is indeed
needlessly complicated. This redesign has the following goals:
1/ Simplify reference counting: dma channels are not something one would
expect to be hotplugged, it should be an exceptional event handled by
drivers not something clients should be mandated to handle in a
callback. The common case channel removal event is 'rmmod <dma driver>',
which for simplicity should be disallowed if the channel is in use.
2/ Add an interface for requesting exclusive access to a channel
suitable to device-to-memory users.
3/ Convert all memory-to-memory users over to a common allocator, the goal
here is to not have competing channel allocation schemes. The only
competition should be between device-to-memory exclusive allocations and
the memory-to-memory usage case where channels are shared between
multiple "clients".
Cc: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Jeff Garzik <jeff@garzik.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dma/dw_dmac.c')
0 files changed, 0 insertions, 0 deletions