commit 88968d99f8f93b2ba4f0b17fd6f10d79188f778c
Author: Pierre Willenbrock <pierre@pirsoft.de>
Date:   Tue Dec 2 12:43:55 2008 +0100

    potential fix

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index c367358..a821462 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -189,6 +189,8 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
 		vblank_enable = I915_VBLANK_INTERRUPT_ENABLE;
 	}
 
+	volatile int _delay_count;
+
 	for (;;) {
 		irq_received = iir != 0;
 
@@ -261,6 +263,8 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
 		 * stray interrupts.
 		 */
 		iir = new_iir;
+		/* counting to 100 is not enough */
+		for(_delay_count=0; _delay_count < 1000; _delay_count++) {}
 	}
 
 	return ret;