linux-kernel - Re: [PATCH v3 10/12] media: i2c: imx214: Verify chip ID

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Message-ID: <Z1g2tLicdrb6lfoK@kekkonen.localdomain>
Date: Tue, 10 Dec 2024 12:40:20 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: git@...tzsch.eu
Cc: Ricardo Ribalda <ribalda@...nel.org>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	Dave Stevenson <dave.stevenson@...pberrypi.com>,
	Vincent Knecht <vincent.knecht@...loo.org>,
	Ricardo Ribalda <ribalda@...omium.org>
Subject: Re: [PATCH v3 10/12] media: i2c: imx214: Verify chip ID

Hi André,

Thanks for the update.

On Sat, Dec 07, 2024 at 09:47:59PM +0100, André Apitzsch via B4 Relay wrote:
> From: André Apitzsch <git@...tzsch.eu>
> 
> Check the chip ID and stop probing if it is no imx214 sensor.
> 
> Acked-by: Ricardo Ribalda <ribalda@...omium.org>
> Signed-off-by: André Apitzsch <git@...tzsch.eu>
> ---
>  drivers/media/i2c/imx214.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/media/i2c/imx214.c b/drivers/media/i2c/imx214.c
> index a35e4e60e55c2b9d9e3090c98e695f78d099cf44..3cd64bb91795d8490acad5926940c111fb95fae5 100644
> --- a/drivers/media/i2c/imx214.c
> +++ b/drivers/media/i2c/imx214.c
> @@ -20,6 +20,10 @@
>  #include <media/v4l2-fwnode.h>
>  #include <media/v4l2-subdev.h>
>  
> +/* Chip ID */
> +#define IMX214_REG_CHIP_ID		CCI_REG16(0x0016)
> +#define IMX214_CHIP_ID			0x0214
> +
>  #define IMX214_REG_MODE_SELECT		CCI_REG8(0x0100)
>  #define IMX214_MODE_STANDBY		0x00
>  #define IMX214_MODE_STREAMING		0x01
> @@ -1092,6 +1096,27 @@ static int imx214_get_regulators(struct device *dev, struct imx214 *imx214)
>  				       imx214->supplies);
>  }
>  
> +/* Verify chip ID */
> +static int imx214_identify_module(struct imx214 *imx214)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&imx214->sd);
> +	int ret;
> +	u64 val;
> +
> +	ret = cci_read(imx214->regmap, IMX214_REG_CHIP_ID, &val, NULL);
> +	if (ret)
> +		return dev_err_probe(&client->dev, ret,
> +				     "failed to read chip id %x\n",
> +				     IMX214_CHIP_ID);
> +
> +	if (val != IMX214_CHIP_ID)
> +		return dev_err_probe(&client->dev, -EIO,
> +				     "chip id mismatch: %x!=%llx\n",
> +				     IMX214_CHIP_ID, val);
> +
> +	return 0;
> +}
> +
>  static int imx214_parse_fwnode(struct device *dev)
>  {
>  	struct fwnode_handle *endpoint;
> @@ -1184,6 +1209,10 @@ static int imx214_probe(struct i2c_client *client)
>  	 */
>  	imx214_power_on(imx214->dev);
>  
> +	ret = imx214_identify_module(imx214);
> +	if (ret)
> +		goto error_power_off;

The error handling was wrong in the driver, the code under the
error_power_off label only disables the regulator (and runtime PM, which
hasn't been enabled) but it does not disable or unprepare the clock. Could
you fix these in a new patch, please?

> +
>  	pm_runtime_set_active(imx214->dev);
>  	pm_runtime_enable(imx214->dev);
>  	pm_runtime_idle(imx214->dev);
> 

-- 
Kind regards,

Sakari Ailus