#define INTEL_INFO(p)  (&__I915__(p)->info)
 #define INTEL_GEN(p)   (INTEL_INFO(p)->gen)
 #define INTEL_DEVID(p) (INTEL_INFO(p)->device_id)
-#define INTEL_REVID(p) (__I915__(p)->dev->pdev->revision)
 
 #define REVID_FOREVER          0xff
+#define INTEL_REVID(p) (__I915__(p)->dev->pdev->revision)
+
+#define GEN_FOREVER (0)
+/*
+ * Returns true if Gen is in inclusive range [Start, End].
+ *
+ * Use GEN_FOREVER for unbound start and or end.
+ */
+#define IS_GEN(p, s, e) ({ \
+       unsigned int __s = (s), __e = (e); \
+       BUILD_BUG_ON(!__builtin_constant_p(s)); \
+       BUILD_BUG_ON(!__builtin_constant_p(e)); \
+       if ((__s) != GEN_FOREVER) \
+               __s = (s) - 1; \
+       if ((__e) == GEN_FOREVER) \
+               __e = BITS_PER_LONG - 1; \
+       else \
+               __e = (e) - 1; \
+       !!(INTEL_INFO(p)->gen_mask & GENMASK((__e), (__s))); \
+})
+
 /*
  * Return true if revision is in range [since,until] inclusive.
  *
 
 
        /* FIXME: We lack the proper locking here, so only run this on the
         * platforms that need. */
-       if (INTEL_INFO(dev_priv)->gen >= 5 && INTEL_INFO(dev_priv)->gen < 7)
+       if (IS_GEN(dev_priv, 5, 6))
                cache->fb.ilk_ggtt_offset = i915_gem_obj_ggtt_offset(obj);
        cache->fb.pixel_format = fb->pixel_format;
        cache->fb.stride = fb->pitches[0];
 
         * arises: do we still need this and if so how should we go about
         * invalidating the TLB?
         */
-       if (INTEL_GEN(dev_priv) >= 6 && INTEL_GEN(dev_priv) < 8) {
+       if (IS_GEN(dev_priv, 6, 7)) {
                i915_reg_t reg = RING_INSTPM(engine->mmio_base);
 
                /* ring should be idle before issuing a sync flush*/
                return ret;
 
        /* WaTimedSingleVertexDispatch:cl,bw,ctg,elk,ilk,snb */
-       if (INTEL_GEN(dev_priv) >= 4 && INTEL_GEN(dev_priv) < 7)
+       if (IS_GEN(dev_priv, 4, 6))
                I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(VS_TIMER_DISPATCH));
 
        /* We need to disable the AsyncFlip performance optimisations in order
         *
         * WaDisableAsyncFlipPerfMode:snb,ivb,hsw,vlv
         */
-       if (INTEL_GEN(dev_priv) >= 6 && INTEL_GEN(dev_priv) < 8)
+       if (IS_GEN(dev_priv, 6, 7))
                I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(ASYNC_FLIP_PERF_DISABLE));
 
        /* Required for the hardware to program scanline values for waiting */
                           _MASKED_BIT_DISABLE(CM0_STC_EVICT_DISABLE_LRA_SNB));
        }
 
-       if (INTEL_GEN(dev_priv) >= 6 && INTEL_GEN(dev_priv) < 8)
+       if (IS_GEN(dev_priv, 6, 7))
                I915_WRITE(INSTPM, _MASKED_BIT_ENABLE(INSTPM_FORCE_ORDERING));
 
        if (HAS_L3_DPF(dev_priv))