Messages in this thread | | | Subject | Re: [PATCH 2/2] dma: mv_xor: do not sync the DMA buffer after being deallocated | From | Lubomir Rintel <> | Date | Sun, 13 Jan 2013 14:18:57 +0100 |
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On Fri, 2013-01-04 at 17:10 +0100, Thomas Petazzoni wrote: > Dear Lubomir Rintel, > > On Thu, 27 Dec 2012 20:23:48 +0100, Lubomir Rintel wrote: > > > dma_sync_single_for_cpu(dma_chan->device->dev, dest_dma, > > MV_XOR_TEST_SIZE, DMA_FROM_DEVICE); > > + dma_unmap_single(dma_chan->device->dev, dest_dma, MV_XOR_TEST_SIZE, > > + DMA_FROM_DEVICE); > > I would assume that dma_unmap_single() implies a > dma_sync_single_for_cpu() since you're unmapping the DMA buffer. So if > you use dma_unmap_single(), I think you can remove the call to > dma_sync_single_for_cpu().
Yes, it indeed seems to be the case (comment for arm_dma_unmap_page(): "After this call, reads by the CPU to the buffer are guaranteed to see whatever the device wrote there.".
> > dma_sync_single_for_cpu(dma_chan->device->dev, dest_dma, > > PAGE_SIZE, DMA_FROM_DEVICE); > > + dma_unmap_page(dma_chan->device->dev, dest_dma, PAGE_SIZE, > > + DMA_FROM_DEVICE); > > Ditto. > > Also, the mv_xor_memcpy_self_test() function not only dma_map_single() > the destination buffer, but also the source buffer. So presumably, the > source buffer should also be dma_unmap_single()'d. > > And for the mv_xor_xor_self_test() function, multiple source buffers > are dma_map_page()'d, so they should all be dma_unmap_page()'d I guess, > not only the destination buffer.
Those get released by the mv_xor_run_tx_complete_actions() callback.
I will follow up with an updated patch.
Regards, Lubo
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