drm/i915: Dont enable CS_PARSER_ERROR interrupts at all

We stopped handling them in

commit aaecdf611a05cac26a94713bad25297e60225c29
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Nov 4 15:52:22 2014 +0100

    drm/i915: Stop gathering error states for CS error interrupts

but just clearing is apparently not enough: A sufficiently dead gpu
left behind by firmware (*cough* coreboot *cough*) can keep the gpu in
an endless loop of such interrupts, eventually leading to the nmi
firing. And definitely to what looks like a machine hang.

Since we don't even enable these interrupts on gen5+ let's do the same
on earlier platforms.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=93171
Tested-by: Mono <mono-for-kernel-org@donderklumpen.de>
Tested-by: info@gluglug.org.uk
Cc: stable@vger.kernel.org
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -3598,14 +3598,12 @@ static int i8xx_irq_postinstall(struct drm_device *dev)
 		~(I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
 		  I915_DISPLAY_PIPE_B_EVENT_INTERRUPT |
 		  I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT |
-		  I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT |
-		  I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT);
+		  I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT);
 	I915_WRITE16(IMR, dev_priv->irq_mask);
 
 	I915_WRITE16(IER,
 		     I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
 		     I915_DISPLAY_PIPE_B_EVENT_INTERRUPT |
-		     I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT |
 		     I915_USER_INTERRUPT);
 	POSTING_READ16(IER);
 
@@ -3767,14 +3765,12 @@ static int i915_irq_postinstall(struct drm_device *dev)
 		  I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
 		  I915_DISPLAY_PIPE_B_EVENT_INTERRUPT |
 		  I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT |
-		  I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT |
-		  I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT);
+		  I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT);
 
 	enable_mask =
 		I915_ASLE_INTERRUPT |
 		I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
 		I915_DISPLAY_PIPE_B_EVENT_INTERRUPT |
-		I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT |
 		I915_USER_INTERRUPT;
 
 	if (I915_HAS_HOTPLUG(dev)) {