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

-----Original Message-----
From: Vinod Koul [mailto:vinod.koul at intel.com]
Sent: Tuesday, September 03, 2013 7:32 PM
To: Lu Jingchang-B35083
Cc: shawn.guo at linaro.org; linux-kernel at vger.kernel.org; linux-arm-
kernel at lists.infradead.org; devicetree at vger.kernel.org
Subject: Re: [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:

quoted

  Do you mean the DMA_SLAVE_CONFIG device_control? Yeah, the slave

driver could pass

quoted

the slave_id. But the DMA_SLAVE_CONFIG may be called more than once,

and the eDMA

quoted

driver just needs to set the slave id once for any given channel, after

that the

quoted

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.

Yeah, I think we should just configure the slave id once and this would make the
configuration simply. But by debugging, I find the dmaengine_slave_config() may be
called more one times after requested by on user. So I put the slave id configuration
in the channel request phase. And the effect is the same for exclusive channel.
Thanks!


Best Regards,
Jingchang