[Intel-gfx] [RFC 33/60] drm/i915/lmem: support pwrite

[Matthew Auld]

On 13/07/2020 06:09, Dave Airlie wrote:
> On Fri, 10 Jul 2020 at 22:00, Matthew Auld <matthew.auld at intel.com> wrote:
>>
>> We need to add support for pwrite'ing an LMEM object.
> 
> why? DG1 is a discrete GPU, these interfaces we already gross and
> overly hacky for integrated, I'd prefer not to drag them across into
> discrete land.
> 
> same goes for pread.
> 
> You have no legacy userspace here, userspace needs change to support
> LMEM, it can be fixed to avoid legacy ioctls paths.

Ok, there have also been similar discussions internally in the past. I 
think one of the reasons was around IGT, and how keeping the 
pread/pwrite interface meant slightly less pain, also it's not much 
effort to implement for LMEM. If this is a NACK, then I guess the other 
idea was to somehow fallback to mmap and update IGT accordingly.

> 
> Dave.
>