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Date:   Tue, 11 Oct 2022 08:13:50 +0000
From:   Sakari Ailus <sakari.ailus@linux.intel.com>
To:     Prabhakar <prabhakar.csengg@gmail.com>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Hans Verkuil <hverkuil@xs4all.nl>,
        Shawn Tu <shawnx.tu@intel.com>,
        Jacopo Mondi <jacopo@jmondi.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-renesas-soc@vger.kernel.org,
        Biju Das <biju.das.jz@bp.renesas.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Subject: Re: [PATCH] media: i2c: ov5645: Use runtime PM
Message-ID: <Y0Ulvmyg8rBOPbRF@paasikivi.fi.intel.com>
References: <20220927201634.750141-1-prabhakar.mahadev-lad.rj@bp.renesas.com>
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In-Reply-To: <20220927201634.750141-1-prabhakar.mahadev-lad.rj@bp.renesas.com>
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Hi Prabhakar,

Thanks for the patch. It's great to see drivers moving to runtime PM!

On Tue, Sep 27, 2022 at 09:16:34PM +0100, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> 
> Switch to using runtime PM for power management.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> ---
>  drivers/media/i2c/Kconfig  |   2 +-
>  drivers/media/i2c/ov5645.c | 135 +++++++++++++++++++------------------
>  2 files changed, 69 insertions(+), 68 deletions(-)
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 7806d4b81716..c0edd1017fe8 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -459,7 +459,7 @@ config VIDEO_OV5640
>  config VIDEO_OV5645
>  	tristate "OmniVision OV5645 sensor support"
>  	depends on OF
> -	depends on I2C && VIDEO_DEV
> +	depends on I2C && PM && VIDEO_DEV
>  	select MEDIA_CONTROLLER
>  	select VIDEO_V4L2_SUBDEV_API
>  	select V4L2_FWNODE
> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> index 81e4e87e1821..3c3b30338328 100644
> --- a/drivers/media/i2c/ov5645.c
> +++ b/drivers/media/i2c/ov5645.c
> @@ -27,6 +27,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_graph.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/slab.h>
>  #include <linux/types.h>
> @@ -108,7 +109,6 @@ struct ov5645 {
>  	u8 timing_tc_reg21;
>  
>  	struct mutex power_lock; /* lock to protect power state */
> -	int power_count;
>  
>  	struct gpio_desc *enable_gpio;
>  	struct gpio_desc *rst_gpio;
> @@ -635,8 +635,24 @@ static int ov5645_set_register_array(struct ov5645 *ov5645,
>  	return 0;
>  }
>  
> -static int ov5645_set_power_on(struct ov5645 *ov5645)
> +static int ov5645_set_power_off(struct device *dev)
>  {
> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> +	struct ov5645 *ov5645 = to_ov5645(sd);
> +
> +	ov5645_write_reg(ov5645, OV5645_IO_MIPI_CTRL00, 0x58);
> +	gpiod_set_value_cansleep(ov5645->rst_gpio, 1);
> +	gpiod_set_value_cansleep(ov5645->enable_gpio, 0);
> +	clk_disable_unprepare(ov5645->xclk);
> +	regulator_bulk_disable(OV5645_NUM_SUPPLIES, ov5645->supplies);
> +
> +	return 0;
> +}
> +
> +static int ov5645_set_power_on(struct device *dev)
> +{
> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> +	struct ov5645 *ov5645 = to_ov5645(sd);
>  	int ret;
>  
>  	ret = regulator_bulk_enable(OV5645_NUM_SUPPLIES, ov5645->supplies);
> @@ -658,57 +674,19 @@ static int ov5645_set_power_on(struct ov5645 *ov5645)
>  
>  	msleep(20);
>  
> -	return 0;
> -}
> -
> -static void ov5645_set_power_off(struct ov5645 *ov5645)
> -{
> -	gpiod_set_value_cansleep(ov5645->rst_gpio, 1);
> -	gpiod_set_value_cansleep(ov5645->enable_gpio, 0);
> -	clk_disable_unprepare(ov5645->xclk);
> -	regulator_bulk_disable(OV5645_NUM_SUPPLIES, ov5645->supplies);
> -}
> -
> -static int ov5645_s_power(struct v4l2_subdev *sd, int on)
> -{
> -	struct ov5645 *ov5645 = to_ov5645(sd);
> -	int ret = 0;
> -
> -	mutex_lock(&ov5645->power_lock);
> -
> -	/* If the power count is modified from 0 to != 0 or from != 0 to 0,
> -	 * update the power state.
> -	 */
> -	if (ov5645->power_count == !on) {
> -		if (on) {
> -			ret = ov5645_set_power_on(ov5645);
> -			if (ret < 0)
> -				goto exit;
> -
> -			ret = ov5645_set_register_array(ov5645,
> -					ov5645_global_init_setting,
> +	ret = ov5645_set_register_array(ov5645, ov5645_global_init_setting,
>  					ARRAY_SIZE(ov5645_global_init_setting));
> -			if (ret < 0) {
> -				dev_err(ov5645->dev,
> -					"could not set init registers\n");
> -				ov5645_set_power_off(ov5645);
> -				goto exit;
> -			}
> -
> -			usleep_range(500, 1000);
> -		} else {
> -			ov5645_write_reg(ov5645, OV5645_IO_MIPI_CTRL00, 0x58);
> -			ov5645_set_power_off(ov5645);
> -		}
> +	if (ret < 0) {
> +		dev_err(ov5645->dev, "could not set init registers\n");
> +		goto exit;
>  	}
>  
> -	/* Update the power count. */
> -	ov5645->power_count += on ? 1 : -1;
> -	WARN_ON(ov5645->power_count < 0);
> +	usleep_range(500, 1000);
>  
> -exit:
> -	mutex_unlock(&ov5645->power_lock);
> +	return 0;
>  
> +exit:
> +	ov5645_set_power_off(dev);
>  	return ret;
>  }
>  
> @@ -795,7 +773,7 @@ static int ov5645_s_ctrl(struct v4l2_ctrl *ctrl)
>  	int ret;
>  
>  	mutex_lock(&ov5645->power_lock);
> -	if (!ov5645->power_count) {
> +	if (!pm_runtime_get_if_in_use(ov5645->dev)) {
>  		mutex_unlock(&ov5645->power_lock);
>  		return 0;
>  	}
> @@ -827,6 +805,7 @@ static int ov5645_s_ctrl(struct v4l2_ctrl *ctrl)
>  		break;
>  	}
>  
> +	pm_runtime_put_autosuspend(ov5645->dev);
>  	mutex_unlock(&ov5645->power_lock);
>  
>  	return ret;
> @@ -991,6 +970,10 @@ static int ov5645_s_stream(struct v4l2_subdev *subdev, int enable)
>  	int ret;
>  
>  	if (enable) {
> +		ret = pm_runtime_resume_and_get(ov5645->dev);
> +		if (ret < 0)
> +			return ret;
> +
>  		ret = ov5645_set_register_array(ov5645,
>  					ov5645->current_mode->data,
>  					ov5645->current_mode->data_size);
> @@ -998,22 +981,22 @@ static int ov5645_s_stream(struct v4l2_subdev *subdev, int enable)
>  			dev_err(ov5645->dev, "could not set mode %dx%d\n",
>  				ov5645->current_mode->width,
>  				ov5645->current_mode->height);
> -			return ret;
> +			goto err_rpm_put;
>  		}
>  		ret = v4l2_ctrl_handler_setup(&ov5645->ctrls);
>  		if (ret < 0) {
>  			dev_err(ov5645->dev, "could not sync v4l2 controls\n");
> -			return ret;
> +			goto err_rpm_put;
>  		}
>  
>  		ret = ov5645_write_reg(ov5645, OV5645_IO_MIPI_CTRL00, 0x45);
>  		if (ret < 0)
> -			return ret;
> +			goto err_rpm_put;
>  
>  		ret = ov5645_write_reg(ov5645, OV5645_SYSTEM_CTRL0,
>  				       OV5645_SYSTEM_CTRL0_START);
>  		if (ret < 0)
> -			return ret;
> +			goto err_rpm_put;
>  	} else {
>  		ret = ov5645_write_reg(ov5645, OV5645_IO_MIPI_CTRL00, 0x40);
>  		if (ret < 0)
> @@ -1023,14 +1006,15 @@ static int ov5645_s_stream(struct v4l2_subdev *subdev, int enable)
>  				       OV5645_SYSTEM_CTRL0_STOP);
>  		if (ret < 0)
>  			return ret;

Not a problem with this patch and should be addressed separately, but the
caller will just call s_stream(0) and will ignore the return value. You
could complain about the error but still should return 0 when disabling
streaming.

> +		pm_runtime_put(ov5645->dev);
>  	}
>  
>  	return 0;
> -}
>  
> -static const struct v4l2_subdev_core_ops ov5645_core_ops = {
> -	.s_power = ov5645_s_power,
> -};
> +err_rpm_put:
> +	pm_runtime_put(ov5645->dev);
> +	return ret;
> +}
>  
>  static const struct v4l2_subdev_video_ops ov5645_video_ops = {
>  	.s_stream = ov5645_s_stream,
> @@ -1046,7 +1030,6 @@ static const struct v4l2_subdev_pad_ops ov5645_subdev_pad_ops = {
>  };
>  
>  static const struct v4l2_subdev_ops ov5645_subdev_ops = {
> -	.core = &ov5645_core_ops,
>  	.video = &ov5645_video_ops,
>  	.pad = &ov5645_subdev_pad_ops,
>  };
> @@ -1188,11 +1171,9 @@ static int ov5645_probe(struct i2c_client *client)
>  		goto free_ctrl;
>  	}
>  
> -	ret = ov5645_s_power(&ov5645->sd, true);
> -	if (ret < 0) {
> -		dev_err(dev, "could not power up OV5645\n");
> +	ret = ov5645_set_power_on(dev);
> +	if (ret)
>  		goto free_entity;
> -	}
>  
>  	ret = ov5645_read_reg(ov5645, OV5645_CHIP_ID_HIGH, &chip_id_high);
>  	if (ret < 0 || chip_id_high != OV5645_CHIP_ID_HIGH_BYTE) {
> @@ -1209,12 +1190,16 @@ static int ov5645_probe(struct i2c_client *client)
>  
>  	dev_info(dev, "OV5645 detected at address 0x%02x\n", client->addr);
>  
> +	pm_runtime_set_active(dev);
> +	pm_runtime_get_noresume(dev);
> +	pm_runtime_enable(dev);
> +
>  	ret = ov5645_read_reg(ov5645, OV5645_AEC_PK_MANUAL,
>  			      &ov5645->aec_pk_manual);
>  	if (ret < 0) {
>  		dev_err(dev, "could not read AEC/AGC mode\n");
>  		ret = -ENODEV;
> -		goto power_down;
> +		goto err_pm_runtime;
>  	}
>  
>  	ret = ov5645_read_reg(ov5645, OV5645_TIMING_TC_REG20,
> @@ -1222,7 +1207,7 @@ static int ov5645_probe(struct i2c_client *client)
>  	if (ret < 0) {
>  		dev_err(dev, "could not read vflip value\n");
>  		ret = -ENODEV;
> -		goto power_down;
> +		goto err_pm_runtime;
>  	}
>  
>  	ret = ov5645_read_reg(ov5645, OV5645_TIMING_TC_REG21,
> @@ -1230,14 +1215,18 @@ static int ov5645_probe(struct i2c_client *client)
>  	if (ret < 0) {
>  		dev_err(dev, "could not read hflip value\n");
>  		ret = -ENODEV;
> -		goto power_down;
> +		goto err_pm_runtime;
>  	}
>  
> -	ov5645_s_power(&ov5645->sd, false);
> +	pm_runtime_set_autosuspend_delay(dev, 1000);
> +	pm_runtime_use_autosuspend(dev);
> +	pm_runtime_put_autosuspend(dev);

You can also do this after registering async subdev. That allows removing
err_pm_runtime label and the two lines below it.

>  
>  	ret = v4l2_async_register_subdev(&ov5645->sd);
>  	if (ret < 0) {
>  		dev_err(dev, "could not register v4l2 device\n");
> +		pm_runtime_disable(dev);
> +		pm_runtime_set_suspended(dev);
>  		goto free_entity;
>  	}
>  
> @@ -1245,8 +1234,11 @@ static int ov5645_probe(struct i2c_client *client)

Again not a problem in this patch, but ov5645_entity_init_cfg() call here
needs to be done before registering the async subdev.

This could be addressed in a separate patch. Up to you.

>  
>  	return 0;
>  
> +err_pm_runtime:
> +	pm_runtime_disable(dev);
> +	pm_runtime_put_noidle(dev);
>  power_down:
> -	ov5645_s_power(&ov5645->sd, false);
> +	ov5645_set_power_off(dev);
>  free_entity:
>  	media_entity_cleanup(&ov5645->sd.entity);
>  free_ctrl:
> @@ -1264,6 +1256,10 @@ static void ov5645_remove(struct i2c_client *client)
>  	v4l2_async_unregister_subdev(&ov5645->sd);
>  	media_entity_cleanup(&ov5645->sd.entity);
>  	v4l2_ctrl_handler_free(&ov5645->ctrls);
> +	pm_runtime_disable(ov5645->dev);
> +	if (!pm_runtime_status_suspended(ov5645->dev))
> +		ov5645_set_power_off(ov5645->dev);
> +	pm_runtime_set_suspended(ov5645->dev);
>  	mutex_destroy(&ov5645->power_lock);
>  }
>  
> @@ -1279,10 +1275,15 @@ static const struct of_device_id ov5645_of_match[] = {
>  };
>  MODULE_DEVICE_TABLE(of, ov5645_of_match);
>  
> +static const struct dev_pm_ops ov5645_pm_ops = {
> +	SET_RUNTIME_PM_OPS(ov5645_set_power_off, ov5645_set_power_on, NULL)
> +};
> +
>  static struct i2c_driver ov5645_i2c_driver = {
>  	.driver = {
>  		.of_match_table = ov5645_of_match,
>  		.name  = "ov5645",
> +		.pm = &ov5645_pm_ops,
>  	},
>  	.probe_new = ov5645_probe,
>  	.remove = ov5645_remove,

-- 
Kind regards,

Sakari Ailus