On Tuesday 12 May 2015 18:24:43 Brian King wrote:
>
> Commit 5fb1bf8aaa832e1e9ca3198de7bbecb8eff7db9c broke 64 bit DMA for mpt2sas
> on Power.
> That commit changed the sequence for setting up the DMA and coherent DMA
> masks so
> that during initialization the driver requests a 64 bit DMA mask and a 32 bit
> consistent
> DMA mask, then later requests a 64 bit consistent DMA mask. The Power
> architecture does
> not currently support this, which results in always falling back to a 32 bit
> DMA window,
> which has a negative impact on performance. Tweak this algorithm slightly so
> that
> if requesting a 32 bit consistent mask fails after we've successfully set a
> 64 bit
> DMA mask, just try to get a 64 bit consistent mask. This should preserve
> existing
> behavior on platforms that support mixed mask setting and restore previous
> functionality
> to those that do not.
>
> Signed-off-by: Brian King <brk...@linux.vnet.ibm.com>
I believe the way the API is designed, it should guarantee that after
dma_set_mask()
succeeds for a device, dma_set_coherent_mask() with the same mask will also
succeed.
Could you just call dma_set_mask_and_coherent() here to avoid that complex
logic?
Arnd
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