Message-ID: <20200903144713.fyhmhs2bfcz5br6d@uno.localdomain>
Date:   Thu, 3 Sep 2020 17:03:53 +0200
From:   Jacopo Mondi <jacopo@...ndi.org>
To:     Sowjanya Komatineni <skomatineni@...dia.com>
Cc:     thierry.reding@...il.com, jonathanh@...dia.com,
        sakari.ailus@....fi, hverkuil@...all.nl, jacopo+renesas@...ndi.org,
        luca@...aceresoli.net, leonl@...pardimaging.com,
        robh+dt@...nel.org, lgirdwood@...il.com, broonie@...nel.org,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/3] media: i2c: imx274: Add IMX274 power on and off
 sequence

Hello,

On Tue, Sep 01, 2020 at 07:04:38PM -0700, Sowjanya Komatineni wrote:
> IMX274 has VANA analog 2.8V supply, VDIG digital core 1.8V supply,
> and VDDL digital io 1.2V supply which are optional based on camera
> module design.
>
> IMX274 also need external 24Mhz clock and is optional based on
> camera module design.
>
> This patch adds support for IMX274 power on and off to enable and
> disable these supplies and external clock.
>
> Reviewed-by: Luca Ceresoli <luca@...aceresoli.net>
> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
> ---
>  drivers/media/i2c/imx274.c | 134 ++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 131 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/i2c/imx274.c b/drivers/media/i2c/imx274.c
> index a4b9dfd..79bfac3c6 100644
> --- a/drivers/media/i2c/imx274.c
> +++ b/drivers/media/i2c/imx274.c
> @@ -18,7 +18,9 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/of_gpio.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
>  #include <linux/slab.h>
>  #include <linux/v4l2-mediabus.h>
>  #include <linux/videodev2.h>
> @@ -131,6 +133,15 @@
>  #define IMX274_TABLE_WAIT_MS			0
>  #define IMX274_TABLE_END			1
>
> +/* regulator supplies */
> +static const char * const imx274_supply_names[] = {
> +	"vddl",  /* IF (1.2V) supply */
> +	"vdig",  /* Digital Core (1.8V) supply */
> +	"vana",  /* Analog (2.8V) supply */
> +};
> +
> +#define IMX274_NUM_SUPPLIES ARRAY_SIZE(imx274_supply_names)
> +
>  /*
>   * imx274 I2C operation related structure
>   */
> @@ -501,6 +512,8 @@ struct imx274_ctrls {
>   * @frame_rate: V4L2 frame rate structure
>   * @regmap: Pointer to regmap structure
>   * @reset_gpio: Pointer to reset gpio
> + * @supplies: List of analog and digital supply regulators
> + * @inck: Pointer to sensor input clock
>   * @lock: Mutex structure
>   * @mode: Parameters for the selected readout mode
>   */
> @@ -514,6 +527,8 @@ struct stimx274 {
>  	struct v4l2_fract frame_interval;
>  	struct regmap *regmap;
>  	struct gpio_desc *reset_gpio;
> +	struct regulator_bulk_data supplies[IMX274_NUM_SUPPLIES];
> +	struct clk *inck;
>  	struct mutex lock; /* mutex lock for operations */
>  	const struct imx274_mode *mode;
>  };
> @@ -767,6 +782,75 @@ static void imx274_reset(struct stimx274 *priv, int rst)
>  	usleep_range(IMX274_RESET_DELAY1, IMX274_RESET_DELAY2);
>  }
>
> +/*
> + * imx274_power_on - Function called to power on the sensor
> + * @imx274: Pointer to device structure
> + */

Can I say this does not bring much value ? :)
Also the parameter name is wrong

> +static int imx274_power_on(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct stimx274 *imx274 = to_imx274(sd);
> +	int ret;
> +
> +	/* keep sensor in reset before power on */
> +	imx274_reset(imx274, 0);
> +
> +	ret = clk_prepare_enable(imx274->inck);
> +	if (ret) {
> +		dev_err(&imx274->client->dev,
> +			"Failed to enable input clock: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = regulator_bulk_enable(IMX274_NUM_SUPPLIES, imx274->supplies);
> +	if (ret) {
> +		dev_err(&imx274->client->dev,
> +			"Failed to enable regulators: %d\n", ret);
> +		goto fail_reg;
> +	}
> +
> +	usleep_range(1, 2);

usleep_range() allows you to provide an interval in which your timeout
can be coalesced with others. Giving a [1usec, 2usec] range kind of
defeat the purpose. And most than everything, does sleeping for 2usec
serve any real purpose ?


> +	imx274_reset(imx274, 1);
> +
> +	return 0;
> +
> +fail_reg:
> +	regulator_bulk_disable(IMX274_NUM_SUPPLIES, imx274->supplies);

regulator_bulk_enable() disables all the regulators that were enabled
before the one that failed, so I don't think you need this one here

> +	clk_disable_unprepare(imx274->inck);
> +	return ret;
> +}
> +
> +/*
> + * imx274_power_off - Function called to power off the sensor
> + * @imx274: Pointer to device structure
> + */

Same as the above one

> +static int imx274_power_off(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct stimx274 *imx274 = to_imx274(sd);
> +
> +	imx274_reset(imx274, 0);
> +

Is reset before power-off necessary ?

> +	regulator_bulk_disable(IMX274_NUM_SUPPLIES, imx274->supplies);
> +
> +	clk_disable_unprepare(imx274->inck);
> +
> +	return 0;
> +}
> +
> +static int imx274_get_regulators(struct device *dev, struct stimx274 *imx274)

For symmetry with the regulators API I would call this
imx274_regulators_get(). Up to you :)

> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < IMX274_NUM_SUPPLIES; i++)
> +		imx274->supplies[i].supply = imx274_supply_names[i];
> +
> +	return devm_regulator_bulk_get(dev, IMX274_NUM_SUPPLIES,
> +					imx274->supplies);
                                       ^ not sure if it's my email
                                       client but you might have a
                                       wrong indent here

Also, the regulators are optional in the bindings, how do the
regulators API cope with that ? I had a look around and they seems to
assume regulators are provided. I might be mistaken though

> +}
> +
>  /**
>   * imx274_s_ctrl - This is used to set the imx274 V4L2 controls
>   * @ctrl: V4L2 control to be set
> @@ -781,6 +865,9 @@ static int imx274_s_ctrl(struct v4l2_ctrl *ctrl)
>  	struct stimx274 *imx274 = to_imx274(sd);
>  	int ret = -EINVAL;
>
> +	if (!pm_runtime_get_if_in_use(&imx274->client->dev))
> +		return 0;
> +

Right, but then you should call __v4l2_ctrl_handler_setup() in the
s_stream(1) call path to have controls updated (after
pm_runtime_get_sync() call for power on). I had a look at it seems
only exposure is updated.

>  	dev_dbg(&imx274->client->dev,
>  		"%s : s_ctrl: %s, value: %d\n", __func__,
>  		ctrl->name, ctrl->val);
> @@ -811,6 +898,8 @@ static int imx274_s_ctrl(struct v4l2_ctrl *ctrl)
>  		break;
>  	}
>
> +	pm_runtime_put(&imx274->client->dev);
> +
>  	return ret;
>  }
>
> @@ -1327,6 +1416,13 @@ static int imx274_s_stream(struct v4l2_subdev *sd, int on)
>  	mutex_lock(&imx274->lock);
>
>  	if (on) {
> +		ret = pm_runtime_get_sync(&imx274->client->dev);
> +		if (ret < 0) {
> +			pm_runtime_put_noidle(&imx274->client->dev);
> +			mutex_unlock(&imx274->lock);
> +			return ret;
> +		}
> +
>  		/* load mode registers */
>  		ret = imx274_mode_regs(imx274);
>  		if (ret)
> @@ -1362,6 +1458,7 @@ static int imx274_s_stream(struct v4l2_subdev *sd, int on)
>  		ret = imx274_write_table(imx274, imx274_stop);
>  		if (ret)
>  			goto fail;
> +		pm_runtime_put(&imx274->client->dev);
>  	}
>
>  	mutex_unlock(&imx274->lock);
> @@ -1369,6 +1466,7 @@ static int imx274_s_stream(struct v4l2_subdev *sd, int on)
>  	return 0;
>
>  fail:
> +	pm_runtime_put(&imx274->client->dev);
>  	mutex_unlock(&imx274->lock);
>  	dev_err(&imx274->client->dev, "s_stream failed\n");
>  	return ret;
> @@ -1834,6 +1932,14 @@ static int imx274_probe(struct i2c_client *client)
>
>  	mutex_init(&imx274->lock);
>
> +	imx274->inck = devm_clk_get_optional(&client->dev, "inck");

clk_get_optional() might return error. I would check this with IS_ERR

> +	ret = imx274_get_regulators(&client->dev, imx274);
> +	if (ret) {
> +		dev_err(&client->dev,
> +			"Failed to get power regulators, err: %d\n", ret);
> +		return ret;
> +	}
> +
>  	/* initialize format */
>  	imx274->mode = &imx274_modes[IMX274_DEFAULT_BINNING];
>  	imx274->crop.width = IMX274_MAX_WIDTH;
> @@ -1881,15 +1987,23 @@ static int imx274_probe(struct i2c_client *client)
>  		goto err_me;
>  	}
>
> -	/* pull sensor out of reset */
> -	imx274_reset(imx274, 1);
> +	/* power on the sensor */
> +	ret = imx274_power_on(&client->dev);
> +	if (ret < 0) {
> +		dev_err(&client->dev,
> +			"%s : imx274 power on failed\n", __func__);
> +		goto err_me;
> +	}

Doesn't pm_runtime_get calls the poweron function for you ?

But anyway, I don't see the device being probed for, in example,
querying it's VID/PID for identification during the driver's probe
routine. Do you need to power on ?

> +
> +	pm_runtime_set_active(&client->dev);
> +	pm_runtime_enable(&client->dev);
>
>  	/* initialize controls */
>  	ret = v4l2_ctrl_handler_init(&imx274->ctrls.handler, 4);
>  	if (ret < 0) {
>  		dev_err(&client->dev,
>  			"%s : ctrl handler init Failed\n", __func__);
> -		goto err_me;
> +		goto err_disable_rpm;
>  	}
>
>  	imx274->ctrls.handler.lock = &imx274->lock;
> @@ -1951,11 +2065,16 @@ static int imx274_probe(struct i2c_client *client)
>  		goto err_ctrls;
>  	}
>
> +	pm_runtime_idle(&client->dev);
> +
>  	dev_info(&client->dev, "imx274 : imx274 probe success !\n");
>  	return 0;
>
>  err_ctrls:
>  	v4l2_ctrl_handler_free(&imx274->ctrls.handler);
> +err_disable_rpm:
> +	pm_runtime_disable(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
>  err_me:
>  	media_entity_cleanup(&sd->entity);
>  err_regmap:
> @@ -1973,14 +2092,23 @@ static int imx274_remove(struct i2c_client *client)
>
>  	v4l2_async_unregister_subdev(sd);
>  	v4l2_ctrl_handler_free(&imx274->ctrls.handler);
> +
> +	pm_runtime_disable(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
> +
>  	media_entity_cleanup(&sd->entity);
>  	mutex_destroy(&imx274->lock);
>  	return 0;
>  }
>
> +static const struct dev_pm_ops imx274_pm_ops = {
> +	SET_RUNTIME_PM_OPS(imx274_power_off, imx274_power_on, NULL)
> +};
> +
>  static struct i2c_driver imx274_i2c_driver = {
>  	.driver = {
>  		.name	= DRIVER_NAME,
> +		.pm = &imx274_pm_ops,
>  		.of_match_table	= imx274_of_id_table,
>  	},
>  	.probe_new	= imx274_probe,
> --
> 2.7.4
>

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