[Intel-gfx] [PATCH] drm/i915: Add I915_PARAM_MMAP_GTT_VERSION to advertise unlimited mmaps

[Chris Wilson]

On Thu, Aug 25, 2016 at 11:00:54AM +0300, Joonas Lahtinen wrote:
> On ke, 2016-08-24 at 20:42 +0100, Chris Wilson wrote:
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -355,6 +355,14 @@ static int i915_getparam(struct drm_device *dev, void *data,
> >  	case I915_PARAM_MIN_EU_IN_POOL:
> >  		value = INTEL_INFO(dev)->min_eu_in_pool;
> >  		break;
> > +	case I915_PARAM_MMAP_GTT_VERSION:
> > +		/* 0 - Objects have to be smaller than aperture,
> > +		 *     all simultaneous users have to fit within the
> > +		 *     available space within the aperture.
> > +		 * 1 - Objects can any size, and X,Y or untiled
> > +		 */
> > +		value = 1;
> 
> The actual test would be if this function call succeeds, though.
> 
> value = 0 would never be returned, so I'm not sure it'll be useful to
> document as such. So I might document as "Failure to execute the query
> means..."

It's also going to get crowded if we put all snippets of ABI information
here.

If I 

#define I915_MMAP_GTT_VERSION 1
/* ... */

at the start of i915_gem_fault() then hopefully we might remember to
update it.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre