[PATCH v4 3/3] dma: Add Freescale eDMA engine driver support

On Tue, Sep 03, 2013 at 05:43:21AM +0000, Lu Jingchang-B35083 wrote:

  Do you mean the DMA_SLAVE_CONFIG device_control? Yeah, the slave driver could pass
the slave_id. But the DMA_SLAVE_CONFIG may be called more than once, and the eDMA
driver just needs to set the slave id once for any given channel, after that the 
transfer is transparent to the device. 

It depends, for a channel requested, if you are only tranferring to a particular
slave device then it can be confugured once.
so
1. allocate channel
2. dmaengine_slave_config()

then you cnan do preare etc multiple times based on need.

~Vinod

  On the other hand, the DMAMUX's setting procedure requires first disable the dmamux
before setting, then if it is set in DMA_SLAVE_CONFIG, the repeated setting may be
complex and unnecessary. The channel is occupied exclusively by the peripheral.
  So, according the HW feature, I think the eDMA needs only set the slave id once,
and since the of_dma helper has pass the slave id in on xlate, we can get and set
the slave id here. How do you think about this?

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