drm/i915: Avoid reading fbc registers in vain when fbc was never enabled.

If it wasn't never enabled by kernel parameter or platform default
we can avoid reading registers so many times in vain

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 6f3b94b7300bf36445520f2184314c8256f34c8d..1ec3c8f689bc8efe09cff39d12f5eef70c2903e3 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -339,6 +339,12 @@ bool intel_fbc_enabled(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
 
+       /* If it wasn't never enabled by kernel parameter or platform default
+        * we can avoid reading registers so many times in vain
+        */
+       if (!i915.enable_fbc)
+               return false;
+
        if (!dev_priv->display.fbc_enabled)
                return false;