drm/i915: Make IS_GENx macros work on a mask

If instead of numerical comparison me make these test a
bitmask, we enable the compiler to optimize all instances
of IS_GENx || IS_GENy.

v2: Make bit zero of gen mask mean gen 1.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 4abd39f..d205b05 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -760,6 +760,7 @@
 	u8 num_pipes:3;
 	u8 num_sprites[I915_MAX_PIPES];
 	u8 gen;
+	u16 gen_mask;
 	u8 ring_mask; /* Rings supported by the HW */
 	DEV_INFO_FOR_EACH_FLAG(DEFINE_FLAG, SEP_SEMICOLON);
 	/* Register offsets for the various display pipes and transcoders */
@@ -2620,14 +2621,14 @@
  * have their own (e.g. HAS_PCH_SPLIT for ILK+ display, IS_foo for particular
  * chips, etc.).
  */
-#define IS_GEN2(dev)	(INTEL_INFO(dev)->gen == 2)
-#define IS_GEN3(dev)	(INTEL_INFO(dev)->gen == 3)
-#define IS_GEN4(dev)	(INTEL_INFO(dev)->gen == 4)
-#define IS_GEN5(dev)	(INTEL_INFO(dev)->gen == 5)
-#define IS_GEN6(dev)	(INTEL_INFO(dev)->gen == 6)
-#define IS_GEN7(dev)	(INTEL_INFO(dev)->gen == 7)
-#define IS_GEN8(dev)	(INTEL_INFO(dev)->gen == 8)
-#define IS_GEN9(dev)	(INTEL_INFO(dev)->gen == 9)
+#define IS_GEN2(dev)	(INTEL_INFO(dev)->gen_mask & BIT(1))
+#define IS_GEN3(dev)	(INTEL_INFO(dev)->gen_mask & BIT(2))
+#define IS_GEN4(dev)	(INTEL_INFO(dev)->gen_mask & BIT(3))
+#define IS_GEN5(dev)	(INTEL_INFO(dev)->gen_mask & BIT(4))
+#define IS_GEN6(dev)	(INTEL_INFO(dev)->gen_mask & BIT(5))
+#define IS_GEN7(dev)	(INTEL_INFO(dev)->gen_mask & BIT(6))
+#define IS_GEN8(dev)	(INTEL_INFO(dev)->gen_mask & BIT(7))
+#define IS_GEN9(dev)	(INTEL_INFO(dev)->gen_mask & BIT(8))
 
 #define RENDER_RING		(1<<RCS)
 #define BSD_RING		(1<<VCS)