media: vivid: fix control handler mutex deadlock

vivid_update_format_cap() can be called from an s_ctrl callback.
In that case (keep_controls == true) no control framework functions
can be called that take the control handler mutex.

The new call to v4l2_ctrl_modify_dimensions() did exactly that.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: 6bc7643d (media: vivid: add pixel_array test control)
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/test-drivers/vivid/vivid-vid-cap.c

@@ -466,6 +466,14 @@ void vivid_update_format_cap(struct vivid_dev *dev, bool keep_controls)
 	tpg_s_video_aspect(&dev->tpg, vivid_get_video_aspect(dev));
 	tpg_s_pixel_aspect(&dev->tpg, vivid_get_pixel_aspect(dev));
 	tpg_update_mv_step(&dev->tpg);
+
+	/*
+	 * We can be called from within s_ctrl, in that case we can't
+	 * modify controls. Luckily we don't need to in that case.
+	 */
+	if (keep_controls)
+		return;
+
 	dims[0] = roundup(dev->src_rect.width, PIXEL_ARRAY_DIV);
 	dims[1] = roundup(dev->src_rect.height, PIXEL_ARRAY_DIV);
 	v4l2_ctrl_modify_dimensions(dev->pixel_array, dims);