drm/i915: Enable panel fitting for eDP

When trying to set other display mode besides the fixed panel mode, the
panel fitting should be enabled. This is similar to LVDS.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/intel_display.c

@@ -1903,7 +1903,8 @@ static void ironlake_crtc_dpms(struct drm_crtc *crtc, int mode)
 		}
 
 		/* Enable panel fitting for LVDS */
-		if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
+		if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)
+		    || HAS_eDP || intel_pch_has_edp(crtc)) {
 			temp = I915_READ(pf_ctl_reg);
 			I915_WRITE(pf_ctl_reg, temp | PF_ENABLE | PF_FILTER_MED_3x3);