Re: [RFC PATCH 00/12] Ion cleanup in preparation for moving out of staging

From: Brian Starkey
Date: Fri Mar 10 2017 - 05:31:42 EST


On Thu, Mar 09, 2017 at 09:38:49AM -0800, Laura Abbott wrote:
On 03/09/2017 02:00 AM, Benjamin Gaignard wrote:


For me those patches are going in the right direction.

I still have few questions:
- since alignment management has been remove from ion-core, should it
be also removed from ioctl structure ?

Yes, I think I'm going to go with the suggestion to fixup the ABI
so we don't need the compat layer and as part of that I'm also
dropping the align argument.

Is the only motivation for removing the alignment parameter that
no-one got around to using it for something useful yet?
The original comment was true - different devices do have different
alignment requirements.

Better alignment can help SMMUs use larger blocks when mapping,
reducing TLB pressure and the chance of a page table walk causing
display underruns.