drm/i915/gen4: Extra CRT hotplug paranoia

[net-next-2.6.git] / drivers / gpu / drm / i915 / intel_crt.c

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index d5c130202396bff52d96b877abd0b1f8a77cd767..22ff38455731ae00b5b5446d5472391935d6c5bf 100644 (file)
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -217,7 +217,8 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
 {
        struct drm_device *dev = connector->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
-       u32 hotplug_en;
+       u32 hotplug_en, orig, stat;
+       bool ret = false;
        int i, tries = 0;
 
        if (HAS_PCH_SPLIT(dev))
@@ -232,8 +233,8 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
                tries = 2;
        else
                tries = 1;
-       hotplug_en = I915_READ(PORT_HOTPLUG_EN);
-       hotplug_en &= CRT_FORCE_HOTPLUG_MASK;
+       hotplug_en = orig = I915_READ(PORT_HOTPLUG_EN);
+       hotplug_en &= CRT_HOTPLUG_MASK;
        hotplug_en |= CRT_HOTPLUG_FORCE_DETECT;
 
        if (IS_G4X(dev))
@@ -255,11 +256,17 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
                } while (time_after(timeout, jiffies));
        }
 
-       if ((I915_READ(PORT_HOTPLUG_STAT) & CRT_HOTPLUG_MONITOR_MASK) !=
-           CRT_HOTPLUG_MONITOR_NONE)
-               return true;
+       stat = I915_READ(PORT_HOTPLUG_STAT);
+       if ((stat & CRT_HOTPLUG_MONITOR_MASK) != CRT_HOTPLUG_MONITOR_NONE)
+               ret = true;
+
+       /* clear the interrupt we just generated, if any */
+       I915_WRITE(PORT_HOTPLUG_STAT, CRT_HOTPLUG_INT_STATUS);
 
-       return false;
+       /* and put the bits back */
+       I915_WRITE(PORT_HOTPLUG_EN, orig);
+
+       return ret;
 }
 
 static bool intel_crt_detect_ddc(struct drm_encoder *encoder)