drm/i915: Increase max fence pitch limit to 256KB on IVB+

BSpec contains several scattered notes which state that the maximum
fence stride was increased to 256KB on IVB.

Testing on real hardware agrees.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_tiling.c

@@ -217,9 +217,12 @@ i915_tiling_ok(struct drm_device *dev, int stride, int size, int tiling_mode)
 		tile_width = 512;
 
 	/* check maximum stride & object size */
-	if (INTEL_INFO(dev)->gen >= 4) {
-		/* i965 stores the end address of the gtt mapping in the fence
+	/* i965+ stores the end address of the gtt mapping in the fence
 	 * reg, so dont bother to check the size */
+	if (INTEL_INFO(dev)->gen >= 7) {
+		if (stride / 128 > GEN7_FENCE_MAX_PITCH_VAL)
+			return false;
+	} else if (INTEL_INFO(dev)->gen >= 4) {
 		if (stride / 128 > I965_FENCE_MAX_PITCH_VAL)
 			return false;
 	} else {

drivers/gpu/drm/i915/i915_reg.h

@@ -430,6 +430,7 @@
 
 #define FENCE_REG_SANDYBRIDGE_0		0x100000
 #define   SANDYBRIDGE_FENCE_PITCH_SHIFT	32
+#define   GEN7_FENCE_MAX_PITCH_VAL	0x0800
 
 /* control register for cpu gtt access */
 #define TILECTL				0x101000