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Diffstat (limited to 'Documentation/dmaengine/client.txt')
| -rw-r--r-- | Documentation/dmaengine/client.txt | 23 |
1 files changed, 6 insertions, 17 deletions
diff --git a/Documentation/dmaengine/client.txt b/Documentation/dmaengine/client.txt index 11fb87ff6cd0..4b04d8988708 100644 --- a/Documentation/dmaengine/client.txt +++ b/Documentation/dmaengine/client.txt @@ -22,25 +22,14 @@ The slave DMA usage consists of following steps: Channel allocation is slightly different in the slave DMA context, client drivers typically need a channel from a particular DMA controller only and even in some cases a specific channel is desired. - To request a channel dma_request_channel() API is used. + To request a channel dma_request_chan() API is used. Interface: - struct dma_chan *dma_request_channel(dma_cap_mask_t mask, - dma_filter_fn filter_fn, - void *filter_param); - where dma_filter_fn is defined as: - typedef bool (*dma_filter_fn)(struct dma_chan *chan, void *filter_param); - - The 'filter_fn' parameter is optional, but highly recommended for - slave and cyclic channels as they typically need to obtain a specific - DMA channel. - - When the optional 'filter_fn' parameter is NULL, dma_request_channel() - simply returns the first channel that satisfies the capability mask. - - Otherwise, the 'filter_fn' routine will be called once for each free - channel which has a capability in 'mask'. 'filter_fn' is expected to - return 'true' when the desired DMA channel is found. + struct dma_chan *dma_request_chan(struct device *dev, const char *name); + + Which will find and return the 'name' DMA channel associated with the 'dev' + device. The association is done via DT, ACPI or board file based + dma_slave_map matching table. A channel allocated via this interface is exclusive to the caller, until dma_release_channel() is called. |