linux-kernel - Re: [PATCH 4/6] media: imx208: Support device probe in non-zero ACPI D state

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Date:   Tue, 14 Dec 2021 17:59:43 +0200
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Bingbu Cao <bingbu.cao@...el.com>
Cc:     linux-media@...r.kernel.org, rafael@...nel.org,
        shawnx.tu@...el.com, tian.shu.qiu@...el.com,
        chiranjeevi.rapolu@...el.com, hyungwoo.yang@...el.com,
        tfiga@...omium.org, senozhatsky@...omium.org,
        linux-kernel@...r.kernel.org, bingbu.cao@...ux.intel.com
Subject: Re: [PATCH 4/6] media: imx208: Support device probe in non-zero ACPI
 D state

Hi Bingbu,

On Tue, Nov 09, 2021 at 04:48:33PM +0800, Bingbu Cao wrote:
> Tell ACPI device PM code that the driver supports the device being in
> non-zero ACPI D state when the driver's probe function is entered.
> 
> Also do identification on the first access of the device, whether in probe
> or when starting streaming.
> 
> Signed-off-by: Bingbu Cao <bingbu.cao@...el.com>
> ---
>  drivers/media/i2c/imx208.c | 77 +++++++++++++++++++++++++++++-----------------
>  1 file changed, 48 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/media/i2c/imx208.c b/drivers/media/i2c/imx208.c
> index 6f3d9c1b5879..b9f6d5f33b58 100644
> --- a/drivers/media/i2c/imx208.c
> +++ b/drivers/media/i2c/imx208.c
> @@ -296,6 +296,9 @@ struct imx208 {
>  	/* OTP data */
>  	bool otp_read;
>  	char otp_data[IMX208_OTP_SIZE];
> +
> +	/* True if the device has been identified */
> +	bool identified;
>  };
>  
>  static inline struct imx208 *to_imx208(struct v4l2_subdev *_sd)
> @@ -619,6 +622,34 @@ static int imx208_set_pad_format(struct v4l2_subdev *sd,
>  	return 0;
>  }
>  
> +static int imx208_identify_module(struct imx208 *imx208)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&imx208->sd);
> +	int ret;
> +	u32 val;
> +
> +	if (imx208->identified)
> +		return 0;

Otp access requires this as well.

How about adding a runtime PM resume callback for this?

I guess it'd be better for the rest, too. Up to you.

> +
> +	ret = imx208_read_reg(imx208, IMX208_REG_CHIP_ID,
> +			      2, &val);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to read chip id %x\n",
> +			IMX208_CHIP_ID);
> +		return ret;
> +	}
> +
> +	if (val != IMX208_CHIP_ID) {
> +		dev_err(&client->dev, "chip id mismatch: %x!=%x\n",
> +			IMX208_CHIP_ID, val);
> +		return -EIO;
> +	}
> +
> +	imx208->identified = true;
> +
> +	return 0;
> +}
> +
>  /* Start streaming */
>  static int imx208_start_streaming(struct imx208 *imx208)
>  {
> @@ -626,6 +657,10 @@ static int imx208_start_streaming(struct imx208 *imx208)
>  	const struct imx208_reg_list *reg_list;
>  	int ret, link_freq_index;
>  
> +	ret = imx208_identify_module(imx208);
> +	if (ret)
> +		return ret;
> +
>  	/* Setup PLL */
>  	link_freq_index = imx208->cur_mode->link_freq_index;
>  	reg_list = &link_freq_configs[link_freq_index].reg_list;
> @@ -752,29 +787,6 @@ static int __maybe_unused imx208_resume(struct device *dev)
>  }
>  
>  /* Verify chip ID */
> -static int imx208_identify_module(struct imx208 *imx208)
> -{
> -	struct i2c_client *client = v4l2_get_subdevdata(&imx208->sd);
> -	int ret;
> -	u32 val;
> -
> -	ret = imx208_read_reg(imx208, IMX208_REG_CHIP_ID,
> -			      2, &val);
> -	if (ret) {
> -		dev_err(&client->dev, "failed to read chip id %x\n",
> -			IMX208_CHIP_ID);
> -		return ret;
> -	}
> -
> -	if (val != IMX208_CHIP_ID) {
> -		dev_err(&client->dev, "chip id mismatch: %x!=%x\n",
> -			IMX208_CHIP_ID, val);
> -		return -EIO;
> -	}
> -
> -	return 0;
> -}
> -
>  static const struct v4l2_subdev_video_ops imx208_video_ops = {
>  	.s_stream = imx208_set_stream,
>  };
> @@ -961,6 +973,7 @@ static int imx208_probe(struct i2c_client *client)
>  {
>  	struct imx208 *imx208;
>  	int ret;
> +	bool full_power;
>  	u32 val = 0;
>  
>  	device_property_read_u32(&client->dev, "clock-frequency", &val);
> @@ -978,11 +991,14 @@ static int imx208_probe(struct i2c_client *client)
>  	/* Initialize subdev */
>  	v4l2_i2c_subdev_init(&imx208->sd, client, &imx208_subdev_ops);
>  
> -	/* Check module identity */
> -	ret = imx208_identify_module(imx208);
> -	if (ret) {
> -		dev_err(&client->dev, "failed to find sensor: %d", ret);
> -		goto error_probe;
> +	full_power = acpi_dev_state_d0(&client->dev);
> +	if (full_power) {
> +		/* Check module identity */
> +		ret = imx208_identify_module(imx208);
> +		if (ret) {
> +			dev_err(&client->dev, "failed to find sensor: %d", ret);
> +			goto error_probe;
> +		}
>  	}
>  
>  	/* Set default mode to max resolution */
> @@ -1017,7 +1033,9 @@ static int imx208_probe(struct i2c_client *client)
>  		goto error_async_subdev;
>  	}
>  
> -	pm_runtime_set_active(&client->dev);
> +	/* Set the device's state to active if it's in D0 state. */
> +	if (full_power)
> +		pm_runtime_set_active(&client->dev);
>  	pm_runtime_enable(&client->dev);
>  	pm_runtime_idle(&client->dev);
>  
> @@ -1077,6 +1095,7 @@ static struct i2c_driver imx208_i2c_driver = {
>  	},
>  	.probe_new = imx208_probe,
>  	.remove = imx208_remove,
> +	.flags = I2C_DRV_ACPI_WAIVE_D0_PROBE,
>  };
>  
>  module_i2c_driver(imx208_i2c_driver);

-- 
Regards,

Sakari Ailus