drm/radeon: don't actually enable the IRQ regs until irq is enabled

vblank can try and enable the IRQ registers before we've set the interrupt
handler up.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_irq.c b/drivers/gpu/drm/radeon/radeon_irq.c
index 97c0599f..99be114 100644
--- a/drivers/gpu/drm/radeon/radeon_irq.c
+++ b/drivers/gpu/drm/radeon/radeon_irq.c
@@ -44,7 +44,8 @@
 	else
 		dev_priv->irq_enable_reg &= ~mask;
 
-	RADEON_WRITE(RADEON_GEN_INT_CNTL, dev_priv->irq_enable_reg);
+	if (!dev->irq_enabled)
+		RADEON_WRITE(RADEON_GEN_INT_CNTL, dev_priv->irq_enable_reg);
 }
 
 static void r500_vbl_irq_set_state(struct drm_device *dev, u32 mask, int state)
@@ -56,7 +57,8 @@
 	else
 		dev_priv->r500_disp_irq_reg &= ~mask;
 
-	RADEON_WRITE(R500_DxMODE_INT_MASK, dev_priv->r500_disp_irq_reg);
+	if (!dev->irq_enabled)
+		RADEON_WRITE(R500_DxMODE_INT_MASK, dev_priv->r500_disp_irq_reg);
 }
 
 int radeon_enable_vblank(struct drm_device *dev, int crtc)
@@ -355,8 +357,6 @@
 	if (!dev_priv)
 		return;
 
-	dev_priv->irq_enabled = 0;
-
 	if ((dev_priv->flags & RADEON_FAMILY_MASK) >= CHIP_RS690)
 		RADEON_WRITE(R500_DxMODE_INT_MASK, 0);
 	/* Disable *all* interrupts */