dGFX have local memory so it do not have aperture and do not support
CPU fences but even for iGFX it have a small number of fences.
As replacement for fences to track frontbuffer modifications by CPU
we have a software tracking that is already in used by FBC and PSR.
PSR don't support fences so it shows that this tracking is reliable.
So lets make fences a nice-to-have to activate FBC for GEN9+(as we
only have a good CI coverage for GEN9+), this will allow us to enable
FBC for dGFXs and iGFXs even when there is no available fence.
intel_fbc_hw_tracking_covers_screen() maybe can also have the same
treatment as fences but BSpec is not clear if the size limitation is
for hardware tracking or general use of FBC and I don't have a 5K
display to test it, so keeping as is for safety.
Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
Signed-off-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_fbc.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 2a3f1333c8ff..1f0d24a1dec1 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -717,11 +717,15 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc)
return false;
}
- /* The use of a CPU fence is mandatory in order to detect writes
- * by the CPU to the scanout and trigger updates to the FBC.
+ /* The use of a CPU fence is one of two ways to detect writes by the
+ * CPU to the scanout and trigger updates to the FBC.
+ *
+ * The other method is by software tracking(see
+ * intel_fbc_invalidate/flush()), it will manually notify FBC and nuke
+ * the current compressed buffer and recompress it.
*
* Note that is possible for a tiled surface to be unmappable (and
- * so have no fence associated with it) due to aperture constaints
+ * so have no fence associated with it) due to aperture constraints
* at the time of pinning.
*
* FIXME with 90/270 degree rotation we should use the fence on
@@ -730,7 +734,7 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc)
* For now this will effecively disable FBC with 90/270 degree
* rotation.
*/
- if (cache->fence_id < 0) {
+ if (cache->fence_id < 0 && INTEL_GEN(dev_priv) < 9) {
fbc->no_fbc_reason = "framebuffer not tiled or fenced";
return false;
}
--
2.25.0
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