drm/i915/tv: Filter out >1024 wide modes that would need vertical scaling on gen3

Since gen3 can't handle >1024 wide sources with vertical scaling
let's not advertize such modes in the mode list. Less tempetation
to the user to try out things that won't work.

v2: s/IS_GEN3(dev_priv/IS_GEN(dev_priv, 3)/
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181112170000.27531-17-ville.syrjala@linux.intel.comReviewed-by: Imre Deak <imre.deak@intel.com>

drivers/gpu/drm/i915/intel_tv.c

@@ -1728,6 +1728,7 @@ intel_tv_set_mode_type(struct drm_display_mode *mode,
 static int
 intel_tv_get_modes(struct drm_connector *connector)
 {
+	struct drm_i915_private *dev_priv = to_i915(connector->dev);
 	const struct tv_mode *tv_mode = intel_tv_mode_find(connector->state);
 	int i, count = 0;
 
@@ -1740,6 +1741,11 @@ intel_tv_get_modes(struct drm_connector *connector)
 		    !tv_mode->component_only)
 			continue;
 
+		/* no vertical scaling with wide sources on gen3 */
+		if (IS_GEN(dev_priv, 3) && input->w > 1024 &&
+		    input->h > intel_tv_mode_vdisplay(tv_mode))
+			continue;
+
 		mode = drm_mode_create(connector->dev);
 		if (!mode)
 			continue;