drm/i915: don't enable vblanks on disabled pipes

In some cases userland may be confused and try to wait on vblank events from
pipes that aren't actually enabled.  We shouldn't allow this, so return
-EINVAL if the pipe isn't on.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@linux.ie>

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 0cadafbef411ba094d020d1323f66f136ba0d1bd..6290219de6c8e832aa4209d761f7d2be0317211b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -411,6 +411,12 @@ int i915_enable_vblank(struct drm_device *dev, int pipe)
 {
        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
        unsigned long irqflags;
+       int pipeconf_reg = (pipe == 0) ? PIPEACONF : PIPEBCONF;
+       u32 pipeconf;
+
+       pipeconf = I915_READ(pipeconf_reg);
+       if (!(pipeconf & PIPEACONF_ENABLE))
+               return -EINVAL;
 
        spin_lock_irqsave(&dev_priv->user_irq_lock, irqflags);
        if (IS_I965G(dev))