[Intel-gfx] [PATCH v4 2/2] drm/i915: Create dumb buffer from LMEM

[Chris Wilson]

Quoting Ramalingam C (2019-12-09 11:57:01)
> On 2019-12-05 at 13:11:29 +0000, Chris Wilson wrote:
> > Quoting Ramalingam C (2019-12-05 13:02:40)
> > > On 2019-12-05 at 12:20:12 +0000, Chris Wilson wrote:
> > > > Quoting Matthew Auld (2019-12-05 12:12:19)
> > > > > We would still need to clear the object(maybe I915_BO_ALLOC_CLEARED?)
> > > > > in order to pass the IGTs. We also need to adjust dumb_buffer.c, since
> > > > > that uses get_avail_ram_mb() for always_clear, but maybe we need the
> > > > > query region uapi for that?
> > > > 
> > > > Hmm. Questions over the maximum size for dumb buffer, maximum number of
> > > > dumb buffers, etc, should be addressed to the dumb API. So some form of
> > > > drmGetCap() ?
> > > Chris, Is this suggestion to add this capability probing through a new IOCTL for
> > > dumb APIs? Please clarify.
> > 
> > I don't think we need a new ioctl, as drm_getcap already covers the dumb
> > buffer API. We just need to expose the limits of the dumb buffer API
> > through it.
> > 
> > The 2 that spring to mind are maximum size of individual buffer and
> > maximum size of total dumb buffers.
> 
> Will there be question for userspace for this extension or no?
> AFAIK There is no consumer except IGT.

There was someone else asking for maximum dumb buffer size on irc from
an application perspective.

But I strongly believe that discoverability and testability of an API
should be a central tenet of API design. :)
-Chris