linux-kernel - [PATCH 2/2] media: i2c: imx290: Check for availability in probe()

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Message-Id: <20240807-imx290-avail-v1-2-666c130c7601@skidata.com>
Date: Wed, 07 Aug 2024 10:10:28 +0200
From: Benjamin Bara <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>, 
 linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Benjamin Bara <benjamin.bara@...data.com>
Subject: [PATCH 2/2] media: i2c: imx290: Check for availability in probe()

Currently, the V4L2 subdevice is also created when the device is not
available/connected. In this case, dmesg shows the following:

[   10.419510] imx290 7-001a: Error writing reg 0x301c: -6
[   10.428981] imx290 7-001a: Error writing reg 0x3020: -6
[   10.442712] imx290 7-001a: Error writing reg 0x3018: -6
[   10.454018] imx290 7-001a: Error writing reg 0x3020: -6

which seems to come from imx290_ctrl_update() after the subdev init is
finished. However, as the errors are ignored, the subdev is initialized
but simply does not work. From userspace perspective, there is no
visible difference between a working and not-working subdevice (except
when trying it out or watching for the error message).

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>
---
 drivers/media/i2c/imx290.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
index 4150e6e4b9a6..a86076e42a36 100644
--- a/drivers/media/i2c/imx290.c
+++ b/drivers/media/i2c/imx290.c
@@ -1580,6 +1580,11 @@ 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, NULL, NULL);
+	if (ret)
+		goto err_pm;
+
 	/* Initialize the V4L2 subdev. */
 	ret = imx290_subdev_init(imx290);
 	if (ret)

-- 
2.46.0