drm/i915: add dynamic performance control support for Ironlake

Ironlake (and 965GM, which this patch doesn't support) supports a
hardware performance and power management feature that allows it to
adjust to changes in GPU load over time with software help.  The goal
if this is to maximize performance/power for a given workload.

This patch enables that feature, which is also a requirement for
supporting Intelligent Power Sharing, a feature which allows for
dynamic budgeting of power between the CPU and GPU in Arrandale
platforms.

Tested-by: ykzhao <yakui.zhao@intel.com>
[anholt: Resolved against the irq handler loop removal]
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index a51573d..3a467ca 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -209,6 +209,8 @@
 extern void intel_crtc_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green,
 				    u16 *blue, int regno);
 extern void intel_init_clock_gating(struct drm_device *dev);
+extern void ironlake_enable_drps(struct drm_device *dev);
+extern void ironlake_disable_drps(struct drm_device *dev);
 
 extern int intel_framebuffer_create(struct drm_device *dev,
 				    struct drm_mode_fb_cmd *mode_cmd,