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

commit 71e0ffa599f54058d9b8724b4b14d0486751681d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 69b9a42da95ed720e85841c00ab7580fdff94830..81ac2bd1fcb7c2bb2003548918e4d8b7e5ada6f0 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -400,6 +400,12 @@ 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))