[PATCH] usb: musb: host: Issue a memory barrier before staring the DMA
stern at rowland.harvard.edu
Thu Aug 5 11:03:33 EDT 2010
On Thu, 5 Aug 2010, Santosh Shilimkar wrote:
> This patch fixes the issue which was observed while transfering
> a large file ( > 20MB) over USB (OMAP MUSB controller acts as USB host)
> to an attached USB thumb drive.
> It was found that CDB field of CBW packet was set to 0x0. This was
> due to missing a barrier before DMA engine starts transfer.
> This buffer is allocated using dma_alloc_coherent which gives
> non-cacheble but bufferable memory and hence needed a write
> memory barrier to flush the write buffer.
If you see this problem when the controller uses DMA acting as a host,
does this mean the same problem might occur when it uses DMA acting as
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