Hi Baoquan,
On Sun, Dec 13, 2015 at 09:19:29AM +0800, Baoquan He wrote:
>From definition and usage for other arch/component set_dma_mask is only
> used to set the DMA addressing limitations which is I got from reading.
> Could you please give more tips on this? Maybe I didn't dig into it deep
> enough to get it.
The device drivers usually call set_dma_mask before they issue any other
dma-api call. So they call it at driver-init time, making the call-back
a good indication that a driver is about to grab a device. As a bonus we
also get the dma-mask and can make choices on how to initialize the
device. But that is out-of-scope for this patch-set.
Joerg
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