drm/vc4: Fix handling of interlaced video modes.

We must not apply CRTC_INTERLACE_HALVE_V to interlaced modes during
mode enumeration, as drm_helper_probe_single_connector_modes
does, so wrap it and reset the effect of CRTC_INTERLACE_HALVE_V
on affected interlaced modes.

Also mode_fixup interlaced modes passed in from user space.

This fixes the vblank timestamping constants and entries in
the mode->crtc_xxx fields needed for precise vblank timestamping.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -208,10 +208,35 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 	return ret;
 }
 
+/*
+ * drm_helper_probe_single_connector_modes() applies drm_mode_set_crtcinfo to
+ * all modes with flag CRTC_INTERLACE_HALVE_V. We don't want this, as it
+ * screws up vblank timestamping for interlaced modes, so fix it up.
+ */
+static int vc4_hdmi_connector_probe_modes(struct drm_connector *connector,
+					  uint32_t maxX, uint32_t maxY)
+{
+	struct drm_display_mode *mode;
+	int count;
+
+	count = drm_helper_probe_single_connector_modes(connector, maxX, maxY);
+	if (count == 0)
+		return 0;
+
+	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] probed adapted modes :\n",
+		      connector->base.id, connector->name);
+	list_for_each_entry(mode, &connector->modes, head) {
+		drm_mode_set_crtcinfo(mode, 0);
+		drm_mode_debug_printmodeline(mode);
+	}
+
+	return count;
+}
+
 static const struct drm_connector_funcs vc4_hdmi_connector_funcs = {
 	.dpms = drm_atomic_helper_connector_dpms,
 	.detect = vc4_hdmi_connector_detect,
-	.fill_modes = drm_helper_probe_single_connector_modes,
+	.fill_modes = vc4_hdmi_connector_probe_modes,
 	.destroy = vc4_hdmi_connector_destroy,
 	.reset = drm_atomic_helper_connector_reset,
 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
@@ -246,7 +271,7 @@ static struct drm_connector *vc4_hdmi_connector_init(struct drm_device *dev,
 	connector->polled = (DRM_CONNECTOR_POLL_CONNECT |
 			     DRM_CONNECTOR_POLL_DISCONNECT);
 
-	connector->interlace_allowed = 0;
+	connector->interlace_allowed = 1;
 	connector->doublescan_allowed = 0;
 
 	drm_mode_connector_attach_encoder(connector, encoder);