[Intel-gfx] [PATCH 12/26] drm/i915: don't disable_fbc() if FBC is already disabled

[Paulo Zanoni]

If FBC is disabled we will still call intel_fbc_invalidate(), and as a
result we may call intel_fbc_deactivate(), which will try to touch
registers.

I'm pretty sure I saw this happen on a runtime suspended device, and
I'm almost sure I was running igt/pm_rpm. It produced the "you touched
registers while the device is suspended" WARNs. But this was some time
ago and I can't remember exactly which conditions were necessary to
reproduce the problem.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/intel_fbc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 6b952ee..80d881f 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -494,7 +494,8 @@ static void intel_fbc_deactivate(struct drm_i915_private *dev_priv)
 
 	intel_fbc_cancel_work(dev_priv);
 
-	dev_priv->fbc.disable_fbc(dev_priv);
+	if (dev_priv->fbc.enabled)
+		dev_priv->fbc.disable_fbc(dev_priv);
 }
 
 static void __intel_fbc_disable(struct drm_i915_private *dev_priv)
-- 
2.6.1