Re: [PATCH] drm/i915: Skip fence installation for objects with rotated views (v2)

Ville Syrjälä
2015-10-27T13:48:42Z

On Tue, Oct 27, 2015 at 01:34:44PM +0000, Tvrtko Ursulin wrote:
>
> On 27/10/15 12:51, Ville Syrjälä wrote:
> > On Mon, Oct 26, 2015 at 06:23:26PM -0700, Vivek Kasireddy wrote:
> >> While pinning a fb object to the display plane, only install a fence
> >> if the object is using a normal view. This corresponds with the
> >> behavior found in i915_gem_object_do_pin() where the fencability
> >> criteria is determined only for objects with normal views.
> >>
> >> v2:
> >> Look at the object's map_and_fenceable flag to determine whether to
> >> install a fence or not (Chris).
> >>
> >> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> >> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> >> Cc: Daniel Vetter <daniel@ffwll.ch>
> >> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> >> ---
> >> drivers/gpu/drm/i915/intel_display.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> >> index 52fb3f2..108c000 100644
> >> --- a/drivers/gpu/drm/i915/intel_display.c
> >> +++ b/drivers/gpu/drm/i915/intel_display.c
> >> @@ -2357,7 +2357,8 @@ intel_pin_and_fence_fb_obj(struct drm_plane *plane,
> >> * framebuffer compression. For simplicity, we always install
> >> * a fence as the cost is not that onerous.
> >> */
> >> - ret = i915_gem_object_get_fence(obj);
> >> + if (obj->map_and_fenceable)
> >
> > This will now get the fence and pin it for the 90/270 view as well,
> > even though the fence doesn't even cover that particualr gtt mapping.
>
> I don't follow. obj->map_and_fenceable will be true only when normal
> view exists, so this avoids setting up the fence when no normal view
> exists and so avoids the WARN_ON in i915_gem_object_get_fence.

Sure, but it's pointless to use up a fence if all we care about
is the 90/270 mapping.

--
Ville Syrjälä
Intel OTC