linux-kernel - [PATCH v3 6/7] media: i2c: imx290: Check for availability in probe()

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Message-Id: <20240902-imx290-avail-v3-6-b32a12799fed@skidata.com>
Date: Mon, 02 Sep 2024 17:57:31 +0200
From: bbara93@...il.com
To: Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
 Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Hans de Goede <hdegoede@...hat.com>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Alexander Stein <alexander.stein@...tq-group.com>, 
 linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Benjamin Bara <benjamin.bara@...data.com>
Subject: [PATCH v3 6/7] media: i2c: imx290: Check for availability in
 probe()

From: Benjamin Bara <benjamin.bara@...data.com>

Currently, the V4L2 subdevice is also created when the device is not
available/connected. From userspace perspective, there is no visible
difference between a working and not-working subdevice (except when
trying it out).

This commit adds a simple availability check before starting with the
subdev initialization to error out instead.

Signed-off-by: Benjamin Bara <benjamin.bara@...data.com>
---
Changes since v2:
- the new 1/8 is split out
- use dev_err_probe() (thx Laurent)
---
 drivers/media/i2c/imx290.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
index 9610e9fd2059..6b292bbb0856 100644
--- a/drivers/media/i2c/imx290.c
+++ b/drivers/media/i2c/imx290.c
@@ -1571,6 +1571,7 @@ static int imx290_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct imx290 *imx290;
+	u64 val;
 	int ret;
 
 	imx290 = devm_kzalloc(dev, sizeof(*imx290), GFP_KERNEL);
@@ -1631,6 +1632,17 @@ static int imx290_probe(struct i2c_client *client)
 	pm_runtime_set_autosuspend_delay(dev, 1000);
 	pm_runtime_use_autosuspend(dev);
 
+	/* Make sure the sensor is available before V4L2 subdev init. */
+	ret = cci_read(imx290->regmap, IMX290_STANDBY, &val, NULL);
+	if (ret) {
+		ret = dev_err_probe(dev, -ENODEV, "Failed to detect sensor\n");
+		goto err_pm;
+	}
+	if (val != IMX290_STANDBY_STANDBY) {
+		ret = dev_err_probe(dev, -ENODEV, "Sensor is not in standby\n");
+		goto err_pm;
+	}
+
 	/* Initialize the V4L2 subdev. */
 	ret = imx290_subdev_init(imx290);
 	if (ret)

-- 
2.46.0