On Wed, Jan 24, 2018 at 10:22:13AM +0000, Will Deacon wrote:

On Wed, Jan 24, 2018 at 12:05:16PM +0300, Yury Norov wrote:

quoted

This series adds API for 128-bit memory IO access and enables it for ARM64.
The original motivation for 128-bit API came from new Cavium network device
driver. The hardware requires 128-bit access to make things work. See
description in patch 3 for details.

Also, starting from ARMv8.4, stp and ldp instructions become atomic, and
API for 128-bit access would be helpful in core arm64 code.

Only for normal, cacheable memory, so they're not suitable for IO accesses
as you're proposing here.

Hi Will,

Thanks for clarification.

Could you elaborate, do you find 128-bit read/write API useless, or
you just correct my comment?

I think that ordered uniform 128-bit access API would be helpful, even
if not atomic.

Yury.