[PATCH] staging: media: tegra-video: vi: fix probe failure on skipped last port

[Hao-Qun Huang <alvinhuang0603@gmail.com>]

tegra_vi_channels_alloc() iterates over port nodes and skips those
whose reg property cannot be read or whose remote endpoint fails
v4l2_fwnode_endpoint_parse(), leaving the negative result of the
failed call in ret. If that happens on the last port node, the loop
ends with ret still negative and tegra_vi_init() fails the whole VI
probe.

The same defective port earlier in the ports node is skipped silently,
so probing succeeds or fails depending on the order of the port nodes.
The CSI equivalent, tegra_csi_channels_alloc(), returns 0
unconditionally after its loop and does not have this problem.

Use a separate variable for the per-port checks so that only fatal
errors end up in ret.

Fixes: 1ebaeb09830f ("media: tegra-video: Add support for external sensor capture")
Fixes: 2ac4035a78c9 ("media: tegra-video: Add support for x8 captures with gang ports")
Assisted-by: Claude:claude-fable-5
Signed-off-by: Hao-Qun Huang <alvinhuang0603@gmail.com>
---
diff --git a/drivers/staging/media/tegra-video/vi.c b/drivers/staging/media/tegra-video/vi.c
index 456134a9e8cf..f461e117305e 100644
--- a/drivers/staging/media/tegra-video/vi.c
+++ b/drivers/staging/media/tegra-video/vi.c
@@ -1257,6 +1257,7 @@ static int tegra_vi_channels_alloc(struct tegra_vi *vi)
 	struct device_node *parent;
 	struct v4l2_fwnode_endpoint v4l2_ep = { .bus_type = 0 };
 	unsigned int lanes;
+	int err;
 	int ret = 0;
 
 	ports = of_get_child_by_name(node, "ports");
@@ -1267,8 +1268,8 @@ static int tegra_vi_channels_alloc(struct tegra_vi *vi)
 		if (!of_node_name_eq(port, "port"))
 			continue;
 
-		ret = of_property_read_u32(port, "reg", &port_num);
-		if (ret < 0)
+		err = of_property_read_u32(port, "reg", &port_num);
+		if (err < 0)
 			continue;
 
 		if (port_num > vi->soc->vi_max_channels) {
@@ -1289,10 +1290,10 @@ static int tegra_vi_channels_alloc(struct tegra_vi *vi)
 
 		ep = of_graph_get_endpoint_by_regs(parent, 0, 0);
 		of_node_put(parent);
-		ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep),
+		err = v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep),
 						 &v4l2_ep);
 		of_node_put(ep);
-		if (ret)
+		if (err)
 			continue;
 
 		lanes = v4l2_ep.bus.mipi_csi2.num_data_lanes;