From bfe4361859005edec5e7ae73274c363910f56d7f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Van=C4=9Bk?= <linuxtardis@gmail.com>
Date: Wed, 7 Jul 2021 22:48:20 +0200
Subject: [PATCH] media: bcm2835-unicam: Forward input status from
 subdevice
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The vidioc_enum_input() v4l2 ioctl is capable of returning
sensor/input status as well. This is used in current
GStreamer HEAD for signal detection [1].

bcm2835-unicam does handle this syscall, but it didn't ask
the subdevice driver about the input status. The input then
appeared as always present.

This commit adds the necessary query. There is a precedent for
this - the R-Car VIN V4L2 driver does a similar call [2].

[1]: https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/blob/ce0be27caf69aa9d96b73bc2b50737451b6f6936/sys/v4l2/gstv4l2src.c#L553
[2]: https://github.com/raspberrypi/linux/blob/7fb9d006d3ff3baf2e205e0c85c4e4fd0a64fcd0/drivers/media/platform/rcar-vin/rcar-v4l2.c#L548

Signed-off-by: Jakub Vaněk <linuxtardis@gmail.com>
---
 drivers/media/platform/bcm2835/bcm2835-unicam.c | 9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/media/platform/bcm2835/bcm2835-unicam.c
+++ b/drivers/media/platform/bcm2835/bcm2835-unicam.c
@@ -1806,6 +1806,7 @@ static int unicam_enum_input(struct file
 {
 	struct unicam_node *node = video_drvdata(file);
 	struct unicam_device *dev = node->dev;
+	int ret;
 
 	if (inp->index != 0)
 		return -EINVAL;
@@ -1822,6 +1823,14 @@ static int unicam_enum_input(struct file
 		inp->capabilities = 0;
 		inp->std = 0;
 	}
+
+	if (v4l2_subdev_has_op(dev->sensor, video, g_input_status)) {
+		ret = v4l2_subdev_call(dev->sensor, video, g_input_status,
+				       &inp->status);
+		if (ret < 0)
+			return ret;
+	}
+
 	snprintf(inp->name, sizeof(inp->name), "Camera 0");
 	return 0;
 }
