drm/i915: add helper for checking whether IRQs are enabled

Now that we use the runtime IRQ enable/disable functions in our suspend
path, we can simply check the pm._irqs_disabled flag everywhere.  So
rename it to catch the users, and add an inline for it to make the
checks clear everywhere.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index bf415df..8fc68c7 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -691,11 +691,19 @@
 void gen8_disable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
 void intel_runtime_pm_disable_interrupts(struct drm_device *dev);
 void intel_runtime_pm_restore_interrupts(struct drm_device *dev);
+static inline bool intel_irqs_enabled(struct drm_i915_private *dev_priv)
+{
+	/*
+	 * We only use drm_irq_uninstall() at unload and VT switch, so
+	 * this is the only thing we need to check.
+	 */
+	return !dev_priv->pm._irqs_disabled;
+}
+
 int intel_get_crtc_scanline(struct intel_crtc *crtc);
 void i9xx_check_fifo_underruns(struct drm_device *dev);
 void gen8_irq_power_well_post_enable(struct drm_i915_private *dev_priv);
 
-
 /* intel_crt.c */
 void intel_crt_init(struct drm_device *dev);