Hi Steve,

On 03/28/2017 03:40 AM, Steve Longerbeam wrote:

+ depends on OF

+	help
+	  This driver provides support for SoC internal N:1 video bus
+	  multiplexers controlled by register bitfields as well as external
+	  2:1 video multiplexers controlled by a single GPIO.
+

[snip]

+static int vidsw_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct of_endpoint endpoint;
+	struct device_node *ep;
+	struct reg_field field;
+	struct vidsw *vidsw;
+	struct regmap *map;
+	unsigned int num_pads;
+	int ret;
+
+	vidsw = devm_kzalloc(&pdev->dev, sizeof(*vidsw), GFP_KERNEL);
+	if (!vidsw)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, vidsw);
+
+	v4l2_subdev_init(&vidsw->subdev, &vidsw_subdev_ops);
+	snprintf(vidsw->subdev.name, sizeof(vidsw->subdev.name), "%s",
+			np->name);

.... or oops here       ^^^^^^^^^.

+	vidsw->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+	vidsw->subdev.dev = &pdev->dev;
+
+	/*
+	 * The largest numbered port is the output port. It determines
+	 * total number of pads
+	 */
+	num_pads = 0;
+	for_each_endpoint_of_node(np, ep) {
+		of_graph_parse_endpoint(ep, &endpoint);
+		num_pads = max(num_pads, endpoint.port + 1);
+	}
+
+	if (num_pads < 2) {
+		dev_err(&pdev->dev, "Not enough ports %d\n", num_pads);
+		return -EINVAL;
+	}

This unveils another runtime dependency on OF.

+
+	ret = of_get_reg_field(np, &field);
+	if (ret == 0) {
+		map = syscon_node_to_regmap(np->parent);
+		if (!map) {
+			dev_err(&pdev->dev, "Failed to get syscon register map\n");
+			return PTR_ERR(map);
+		}
+
+		vidsw->field = devm_regmap_field_alloc(&pdev->dev, map, field);
+		if (IS_ERR(vidsw->field)) {
+			dev_err(&pdev->dev, "Failed to allocate regmap field\n");
+			return PTR_ERR(vidsw->field);
+		}
+
+		regmap_field_read(vidsw->field, &vidsw->active);
+	} else {
+		if (num_pads > 3) {
+			dev_err(&pdev->dev, "Too many ports %d\n", num_pads);
+			return -EINVAL;
+		}
+
+		vidsw->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
+		if (IS_ERR(vidsw->gpio)) {
+			dev_warn(&pdev->dev,
+				 "could not request control gpio: %d\n", ret);
+			vidsw->gpio = NULL;
+		}
+
+		vidsw->active = gpiod_get_value(vidsw->gpio) ? 1 : 0;

vidsw->active is always set to 0 ?

+	}
+
+	vidsw->num_pads = num_pads;
+	vidsw->pads = devm_kzalloc(&pdev->dev, sizeof(*vidsw->pads) * num_pads,
+			GFP_KERNEL);
+	vidsw->format_mbus = devm_kzalloc(&pdev->dev,
+			sizeof(*vidsw->format_mbus) * num_pads, GFP_KERNEL);
+	vidsw->endpoint = devm_kzalloc(&pdev->dev,
+			sizeof(*vidsw->endpoint) * (num_pads - 1), GFP_KERNEL);
+
+	ret = vidsw_async_init(vidsw, np);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+

--
With best wishes,
Vladimir