media: em28xx-cards: disable V4L2 mode for dual tuners

Right now, the code that calculates alternate modes is not ready
for devices with dual tuners. That's ok, as we currently don't
have any such devices, but better to add a warning for such
case, as, if anyone adds such device, the logic will need to
be reviewed.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Brad Love <brad@nextdimension.cc>
Reviewed-by: Michael Ira Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/em28xx/em28xx-cards.c

@@ -3861,6 +3861,17 @@ static int em28xx_usb_probe(struct usb_interface *intf,
 		dev->has_video = false;
 	}
 
+	if (dev->board.has_dual_ts &&
+	    (dev->tuner_type != TUNER_ABSENT || INPUT(0)->type)) {
+		/*
+		 * The logic with sets alternate is not ready for dual-tuners
+		 * which analog modes.
+		 */
+		dev_err(&intf->dev,
+			"We currently don't support analog TV or stream capture on dual tuners.\n");
+		has_video = false;
+	}
+
 	/* Select USB transfer types to use */
 	if (has_video) {
 		if (!dev->analog_ep_isoc || (try_bulk && dev->analog_ep_bulk))