[alsa-devel] [PATCH] dma: add new DMA control commands
b32955 at freescale.com
Thu Oct 18 08:45:41 CEST 2012
于 2012年10月18日 14:18, Vinod Koul 写道:
> Why cant you do start (prepare clock etc) when you submit the descriptor
> to dmaengine. Can be done in tx_submit callback.
> Similarly remove the clock when dma transaction gets completed.
I ever thought this method too.
But it will become low efficient in the following case:
Assuming the gpmi-nand driver has to read out 1024 pages in one
_SINGLE_ read operation.
The gpmi-nand will submit the descriptor to dmaengine per page. So with
the system will repeat the enable/disable dma clock 1024 time. At every
enable/disable dma clock,
the system has to enable the clock chain and it's parents ...
But with this patch, we only need to enable/disable dma clock one time,
just at we select the nand chip.
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