[PATCH 2/3] media: i2c: ov5675: Defer the probe until the endpoint exists

[Alexander Patrakov <patrakov@gmail.com>]

On ACPI systems the sensor's endpoint is a software node which ipu-bridge
creates when the IPU probes. Nothing orders that before the probe of the
sensor. If the sensor is first, there is no endpoint yet, parsing it
fails, and the probe fails for good: the camera is missing until the
next boot.

Return -EPROBE_DEFER when there is no endpoint, as ov2740, ov13b10 and,
since commit 437e1f6a9600 ("media: mt9m114: Return -EPROBE_DEFER if no
endpoint is found"), mt9m114 do.

This failure mode was seen once on a Lenovo Yoga Duet 7 13ITL6.
Reproduction efforts did not succeed.

Signed-off-by: Alexander Patrakov <patrakov@gmail.com>
---
 drivers/media/i2c/ov5675.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/media/i2c/ov5675.c b/drivers/media/i2c/ov5675.c
index c5eb07576129..9cf600c9c94a 100644
--- a/drivers/media/i2c/ov5675.c
+++ b/drivers/media/i2c/ov5675.c
@@ -1182,8 +1182,16 @@ static int ov5675_get_hwcfg(struct ov5675 *ov5675)
 	if (!fwnode)
 		return -ENXIO;
 
+	/*
+	 * On ACPI systems the endpoint is a software node which ipu-bridge
+	 * creates when the IPU probes, which may be after this probe.
+	 */
 	ep = fwnode_graph_get_endpoint_by_id(fwnode, 0, 0,
 					     FWNODE_GRAPH_ENDPOINT_NEXT);
+	if (!ep)
+		return dev_err_probe(dev, -EPROBE_DEFER,
+				     "waiting for fwnode graph endpoint\n");
+
 	ret = v4l2_fwnode_endpoint_alloc_parse(ep, &bus_cfg);
 	fwnode_handle_put(ep);
 	if (ret)
-- 
2.56.0