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dmaengine: centralize channel allocation, introduce dma_find_channel

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Allowing multiple clients to each define their own channel allocation
scheme quickly leads to a pathological situation.  For memory-to-memory
offload all clients can share a central allocator.

This simply moves the existing async_tx allocator to dmaengine with
minimal fixups:
* async_tx.c:get_chan_ref_by_cap --> dmaengine.c:nth_chan
* async_tx.c:async_tx_rebalance --> dmaengine.c:dma_channel_rebalance
* split out common code from async_tx.c:__async_tx_find_channel -->
  dma_find_channel

Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2009-01-06 11:38:14 -07:00
parent 6f49a57aa5
commit bec085134e
3 changed files with 174 additions and 143 deletions
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3
include/linux/dmaengine.h
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@ -182,6 +182,7 @@ struct dma_chan_percpu {
* @device_node: used to add this to the device chan list
* @local: per-cpu pointer to a struct dma_chan_percpu
* @client-count: how many clients are using this channel
* @table_count: number of appearances in the mem-to-mem allocation table
*/
struct dma_chan {
struct dma_device *device;
@ -198,6 +199,7 @@ struct dma_chan {
struct list_head device_node;
struct dma_chan_percpu *local;
int client_count;
int table_count;
};
#define to_dma_chan(p) container_of(p, struct dma_chan, dev)
@ -468,6 +470,7 @@ static inline enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descript
int dma_async_device_register(struct dma_device *device);
void dma_async_device_unregister(struct dma_device *device);
void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type);
/* --- Helper iov-locking functions --- */