drm/i915: add SW tracking to FBC enabling
Currently, calling intel_fbc_enabled() will trigger a register read.
And we call it a lot of times, even when FBC is disabled, so saving a
few cycles would be a good thing.
Another reason for this patch is because we currently call
intel_fbc_enabled() while the HW is runtime suspended, so the read
makes no sense and triggers a WARN. This happens even if FBC is
disabled by default. Of course one could argue that we just shouldn't
be calling intel_fbc_enabled() while the driver is runtime suspended,
and I agree that's a good argument, but I still think that the reason
explained in the first paragraph already justifies the patch.
This problem can easily be reproduced with many subtests of
igt/pm_rpm, and it is a regression introduced by:
commit c5ad011d7d256ecbe173324029e992817194d2b0
Author: Rodrigo Vivi <rodrigo.vivi@intel.com>
Date: Mon Aug 4 03:51:38 2014 -0700
drm/i915: FBC flush nuke for BDW
Testcase: igt/pm_rpm/cursor (and others)
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 5fce16c..999bd57 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -662,6 +662,10 @@
bool false_color;
+ /* Tracks whether the HW is actually enabled, not whether the feature is
+ * possible. */
+ bool enabled;
+
struct intel_fbc_work {
struct delayed_work work;
struct drm_crtc *crtc;