The optimisation inherent in commit 6a2c4232ece1 ("drm/i915: Make the
physical object coherent with GTT") relies on that once we allocated a
cursor we would have coherent, zero overhead access to the scanout plane
holding the cursor. That is we could then do the very frequent cursor
updates X enjoys with no indirection or kernel involvement. However,
that all hinges on the GGTT mmap of the cursor being pinned and not
require refaulting on each access -- handling such a page fault likely
requires the busy GGTT to be rearranged causing a stall. A very simple
fix is then to handle the physical cursor exactly like other cursors and
keep its vma pinned while active.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107600
References: 6a2c4232ece1 ("drm/i915: Make the physical object coherent with GTT")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_display.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 592b847db88e..d47ec9fd4af4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12966,8 +12966,11 @@ static int intel_plane_pin_fb(struct intel_plane_state *plane_state)
INTEL_INFO(dev_priv)->cursor_needs_physical) {
struct drm_i915_gem_object *obj = intel_fb_obj(fb);
const int align = intel_cursor_alignment(dev_priv);
+ int err;
- return i915_gem_object_attach_phys(obj, align);
+ err = i915_gem_object_attach_phys(obj, align);
+ if (err)
+ return err;
}
vma = intel_pin_and_fence_fb_obj(fb,
--
2.18.0
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
