[RFC v4 00/18] vb2: Handle user cache hints, allow drivers to choose cache coherency

[Sakari Ailus]

Hi Mauro,

Mauro Carvalho Chehab wrote:
> Hi Sakari,
>
> Em Mon,  8 May 2017 18:03:12 +0300
> Sakari Ailus <sakari.ailus at linux.intel.com> escreveu:
>
>> Hello,
>>
>> This is a rebased and partially reworked version of the vb2 cache hints
>> support patch series posted by first myself, then Laurent and then myself
>> again.
>>
>> I'm still posting this as RFC primarily because more testing and driver
>> changes will be needed. In particular, a lot of platform drivers assume
>> non-coherent memory but are not properly labelled as such.
>
> The main issue I see is that, if the driver doesn't "annotate" if it
> is requiring coherent or non-coherent memory, VB2 should be preserving
> its old behavior, as, otherwise, it will risk causing regressions.

Some of the assumptions in VB2 mirror the particular design choices made 
in ARM DMA API implementation. This was found out during the review. The 
set requires further work in order to be mergeable to get around these 
issues, until then this remains in RFC stage.

I posted the three first patches separately --- these do not change how 
cache management works.

-- 
Kind regards,

Sakari Ailus
sakari.ailus at linux.intel.com