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Date: Tue, 03 May 2011 10:21:52 +0800
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To: "Koul, Vinod" <vinod.koul@intel.com>
CC: linux-kernel@vger.kernel.org, dan.j.williams@intel.com
Subject: Re: Can I/OAT DMA engineer access PCI MMIO space
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>> I try to use ioatdam to copy data from system memory to pci MMIO space:
>> If dst points to a memory space, the operation would pass.
>> But if dst points to a pci MMIO space, it failed with kernel oops.
>> It seems the code:
>> BUG_ON(is_ioat_bug(chanerr));
>> in drivers/dma/ioat/dma_v3.c, line 365 cause the oops.
>> Is there anyway to access pci MMIO space using ioat?
>> The datasheet says that ioat supports MMIO access.
> Did you map the IO memory in kernel using ioremap and friends first?
>
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.