linux-kernel - [PATCH v4 3/3] media: i2c: imx290: Check for availability in probe()

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Message-Id: <20240903-imx290-avail-v4-3-e4a6c0837f0b@skidata.com>
Date: Tue, 03 Sep 2024 16:54:34 +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>, 
 Alexander Stein <alexander.stein@...tq-group.com>, 
 Dave Stevenson <dave.stevenson@...pberrypi.com>, 
 linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Benjamin Bara <benjamin.bara@...data.com>
Subject: [PATCH v4 3/3] 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 preparation step, which includes an
availability check, before the subdev is initialized.

Signed-off-by: Benjamin Bara <benjamin.bara@...data.com>
---
Changes since v3:
- thanks to the feedback of Dave, I decided to switch to a write instead
  of a read for the availability check.
- instead of only writing the STANDBY register, re-use stop_streaming() to
  ensure a proper state.
- reword commit message.
---
 drivers/media/i2c/imx290.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
index 47cfb6a9e9b5..49a5bf9c17da 100644
--- a/drivers/media/i2c/imx290.c
+++ b/drivers/media/i2c/imx290.c
@@ -1589,6 +1589,16 @@ 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, in STANDBY and not streaming
+	 * before the V4L2 subdev is initialized.
+	 */
+	ret = imx290_stop_streaming(imx290);
+	if (ret) {
+		ret = dev_err_probe(dev, ret, "Could not initialize device\n");
+		goto err_pm;
+	}
+
 	/* Initialize the V4L2 subdev. */
 	ret = imx290_subdev_init(imx290);
 	if (ret)

-- 
2.46.0