linux-kernel - Re: [PATCH v2 1/2] media: i2c: imx290: Check for availability in probe()

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Message-ID: <ZtAdvtkjr0XNbvmu@kekkonen.localdomain>
Date: Thu, 29 Aug 2024 07:05:34 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Benjamin Bara <bbara93@...il.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	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: Re: [PATCH v2 1/2] media: i2c: imx290: Check for availability in
 probe()

Hi Benjamin,

On Wed, Aug 28, 2024 at 08:13:07PM +0200, Benjamin Bara wrote:
> 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>
> ---
> Changes since v1:
> - define operating/standby mode and use it
> - read out the standby mode during probe and ensure it is standby
> ---
>  drivers/media/i2c/imx290.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
> index 4150e6e4b9a6..2a869576600c 100644
> --- a/drivers/media/i2c/imx290.c
> +++ b/drivers/media/i2c/imx290.c
> @@ -29,6 +29,8 @@
>  #include <media/v4l2-subdev.h>
>  
>  #define IMX290_STANDBY					CCI_REG8(0x3000)
> +#define IMX290_STANDBY_OPERATING			(0 << 0)
> +#define IMX290_STANDBY_STANDBY				(1 << 0)
>  #define IMX290_REGHOLD					CCI_REG8(0x3001)
>  #define IMX290_XMSTA					CCI_REG8(0x3002)
>  #define IMX290_ADBIT					CCI_REG8(0x3005)
> @@ -1016,7 +1018,7 @@ static int imx290_start_streaming(struct imx290 *imx290,
>  		return ret;
>  	}
>  
> -	cci_write(imx290->regmap, IMX290_STANDBY, 0x00, &ret);
> +	cci_write(imx290->regmap, IMX290_STANDBY, IMX290_STANDBY_OPERATING, &ret);

Please run

	./scripts/checkpatch.pl --strict --max-line-length=80

the next time. I'll wrap the line this time.

>  
>  	msleep(30);
>  
> @@ -1029,7 +1031,7 @@ static int imx290_stop_streaming(struct imx290 *imx290)
>  {
>  	int ret = 0;
>  
> -	cci_write(imx290->regmap, IMX290_STANDBY, 0x01, &ret);
> +	cci_write(imx290->regmap, IMX290_STANDBY, IMX290_STANDBY_STANDBY, &ret);
>  
>  	msleep(30);
>  
> @@ -1520,6 +1522,7 @@ 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);
> @@ -1580,6 +1583,16 @@ 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 before V4L2 subdev init. */
> +	ret = cci_read(imx290->regmap, IMX290_STANDBY, &val, NULL);
> +	if (ret)
> +		goto err_pm;
> +	if (val != IMX290_STANDBY_STANDBY) {
> +		dev_err(dev, "Sensor is not in standby mode\n");
> +		ret = -ENODEV;
> +		goto err_pm;
> +	}
> +
>  	/* Initialize the V4L2 subdev. */
>  	ret = imx290_subdev_init(imx290);
>  	if (ret)
> 

-- 
Kind regards,

Sakari Ailus