tree c2e0661dbbb76ad83b2645db4291954bbd19c69d
parent cfa93fb9c2eae805f2c16d72bad04ca49b6e16d2
author Paul Burton <paul.burton@imgtec.com> 1475687896 +0100
committer Ralf Baechle <ralf@linux-mips.org> 1475769721 +0200

MIPS: Support per-device DMA coherence

On some MIPS systems, a subset of devices may have DMA coherent with CPU
caches. For example in systems including a MIPS I/O Coherence Unit
(IOCU), some devices may be connected to that IOCU whilst others are
not.

Prior to this patch, we have a plat_device_is_coherent() function but no
implementation which does anything besides return a global true or
false, optionally chosen at runtime. For devices such as those described
above this is insufficient.

Fix this by tracking DMA coherence on a per-device basis with a
dma_coherent field in struct dev_archdata. Setting this from
arch_setup_dma_ops() takes care of devices which set the dma-coherent
property via device tree, and any PCI devices beneath a bridge described
in DT, automatically.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14349/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>