Messages in this thread | | | Date | Sat, 27 Dec 2008 11:10:37 +0100 | From | Haavard Skinnemoen <> | Subject | Re: [PATCH] dmatest: flush and invalidate destination buffer before DMA |
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Atsushi Nemoto wrote: > @@ -226,6 +227,12 @@ static int dmatest_func(void *data) > > dmatest_init_srcbuf(thread->srcbuf, src_off, len); > dmatest_init_dstbuf(thread->dstbuf, dst_off, len); > + /* flush and invalidate caches for whole dstbuf */ > + dma_dest = dma_map_single(chan->device->dev, > + thread->dstbuf, > + test_buf_size, DMA_BIDIRECTIONAL); > + dma_unmap_single(chan->device->dev, dma_dest, > + test_buf_size, DMA_BIDIRECTIONAL);
You're supposed to unmap after the DMA operation is done, not before it's submitted.
In this case, the DMA engine framework will do the unmapping for you (probably using the wrong primitive, but they're really all the same in practice, right?) so you can just drop the unmap call.
Now, I suspect the dw_dmac driver maps the buffer when it's not supposed to, masking this kind of error...should probably get that fixed too.
Haavard
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