Arnd Bergmann wrote:
As I said, this is inherently driver specific. If setting the 64-bit
mask fails, the driver itself needs to fall back to the 32-bit mask
so it can allocate buffers from ZONE_DMA instead of ZONE_NORMAL.
I just posted a v7 of my patch, but I forgot to fix the dma_set_mask
call. I'll post a v8 soon, but before I do, what do you think of this:
/* The EMAC itself is capable of 64-bit DMA, so try that first. */
ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
if (ret) {
/* Some platforms may restrict the EMAC's address bus to less
* then the size of DDR. In this case, we need to try a
* smaller mask. We could try every possible smaller mask,
* but that's overkill. Instead, just fall to 32-bit, which
* should always work.
*/
ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
if (ret) {
dev_err(&pdev->dev, "could not set DMA mask\n");
return ret;
}
}
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