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
your method,
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.
thanks
Huang Shijie
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