Re: Can I/OAT DMA engineer access PCI MMIO space

[Dan Williams]

On 5/2/2011 11:31 PM, ååæ wrote:
> > > yes, I had used 'ioremap_nocache' to map the IO memory and I can use
> > > memcpy to copy data to this region. The async_tx should have been
> > > correctly configured as
> > > I can use aync_memcpy to copy data between different system memory address.
> > Then you should be using memcpy_toio() and friends
> Do you mean that if I have mapped the mmio, I can' use I/OAT dma
> transfer to this region any more?
> I can use memcpy to copy data, but it consumes lots of cpu as PCI access
> is too slow.
> If I can use i/oat dma and asyc_tx api to do the job, the performance
> should be imporved.
> Thanks

The async_tx api only supports memory-to-memory transfers.  To write to 
mmio space with ioatdma you would need a custom method, like the 
dma-slave support in other drivers, to program the descriptors with the 
physical mmio bus address.

--
Dan
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