drm/i2c: tda998x: Choose between atomic or non atomic dpms helper

Choose between atomic or non atomic connector dpms helper. If tda998x
is connected to a drm driver that does not support atomic modeset
calling drm_atomic_helper_connector_dpms() causes a crash when the
connectors atomic state is not initialized. The patch implements a
driver specific connector dpms helper that calls
drm_atomic_helper_connector_dpms() if driver supports DRIVER_ATOMIC
and otherwise it calls the legacy drm_helper_connector_dpms().

Fixes commit 9736e988d328 ("drm/i2c: tda998x: Add support for atomic
modesetting").

Signed-off-by: Jyri Sarha <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/i2c/tda998x_drv.c

···
 	drm_connector_cleanup(connector);
 }
 
+static int tda998x_connector_dpms(struct drm_connector *connector, int mode)
+{
+	if (drm_core_check_feature(connector->dev, DRIVER_ATOMIC))
+		return drm_atomic_helper_connector_dpms(connector, mode);
+	else
+		return drm_helper_connector_dpms(connector, mode);
+}
+
 static const struct drm_connector_funcs tda998x_connector_funcs = {
-	.dpms = drm_atomic_helper_connector_dpms,
+	.dpms = tda998x_connector_dpms,
 	.reset = drm_atomic_helper_connector_reset,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.detect = tda998x_connector_detect,