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Date:   Tue, 31 May 2022 15:16:33 +0200
From:   Jacopo Mondi <jacopo@jmondi.org>
To:     Quentin Schulz <foss+kernel@0leil.net>
Cc:     shawnx.tu@intel.com, mchehab@kernel.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Quentin Schulz <quentin.schulz@theobroma-systems.com>
Subject: Re: [PATCH v5 2/4] media: ov5675: add device-tree support and
 support runtime PM
Message-ID: <20220531131633.tjkp6q43kwwxtnvk@uno.localdomain>
References: <20220525145833.1165437-1-foss+kernel@0leil.net>
 <20220525145833.1165437-2-foss+kernel@0leil.net>
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In-Reply-To: <20220525145833.1165437-2-foss+kernel@0leil.net>
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Hi Quentin,
   one more question

On Wed, May 25, 2022 at 04:58:31PM +0200, Quentin Schulz wrote:
> From: Quentin Schulz <quentin.schulz@theobroma-systems.com>
>
> Until now, this driver only supported ACPI. This adds support for
> Device Tree too while enabling clock and regulators in runtime PM.
>
> Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
> ---
>
> v5:
>  - fixed -Wdeclaration-after-statement for delay_us,
>
> v4:
>  - added delays based on clock cycles as specified in datasheet for
>  pre-power-off and post-power-on,
>  - re-arranged clk handling, shutdown toggling and regulator handling to
>  better match power up/down sequence defined in datasheet,
>  - added comment on need for regulator being stable before releasing
>  shutdown pin,
>
> v3:
>  - added linux/mod_devicetable.h include,
>  - moved delay for reset pulse right after the regulators are enabled,
>  - removed check on is_acpi_node in favor of checks on presence of OF
>  properties (e.g. devm_clk_get_optional returns NULL),
>  - moved power management out of system suspend/resume into runtime PM
>  callbacks,
>  - removed ACPI specific comment since it's not specific to this driver,
>  - changed devm_clk_get to devm_clk_get_optional,
>  - remove OF use of clock-frequency (handled by devm_clk_get_optional
>  directly),
>  - removed name of clock (only one, so no need for anything explicit)
>  when requesting a clock from OF,
>  - wrapped lines to 80 chars,
>
> v2:
>  - fixed unused-const-variable warning by removing of_match_ptr in
>  of_match_table, reported by kernel test robot,
>
>  drivers/media/i2c/ov5675.c | 149 +++++++++++++++++++++++++++++++------
>  1 file changed, 128 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/media/i2c/ov5675.c b/drivers/media/i2c/ov5675.c
> index 82ba9f56baec8..ea801edb8e408 100644
> --- a/drivers/media/i2c/ov5675.c
> +++ b/drivers/media/i2c/ov5675.c
> @@ -3,10 +3,14 @@
>
>  #include <asm/unaligned.h>
>  #include <linux/acpi.h>
> +#include <linux/clk.h>
>  #include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/i2c.h>
> +#include <linux/mod_devicetable.h>
>  #include <linux/module.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/regulator/consumer.h>
>  #include <media/v4l2-ctrls.h>
>  #include <media/v4l2-device.h>
>  #include <media/v4l2-fwnode.h>
> @@ -17,7 +21,7 @@
>
>  #define OV5675_LINK_FREQ_450MHZ		450000000ULL
>  #define OV5675_SCLK			90000000LL
> -#define OV5675_MCLK			19200000
> +#define OV5675_XVCLK_19_2		19200000
>  #define OV5675_DATA_LANES		2
>  #define OV5675_RGB_DEPTH		10
>
> @@ -76,6 +80,14 @@
>
>  #define to_ov5675(_sd)			container_of(_sd, struct ov5675, sd)
>
> +static const char * const ov5675_supply_names[] = {
> +	"avdd",		/* Analog power */
> +	"dovdd",	/* Digital I/O power */
> +	"dvdd",		/* Digital core power */
> +};
> +
> +#define OV5675_NUM_SUPPLIES	ARRAY_SIZE(ov5675_supply_names)
> +
>  enum {
>  	OV5675_LINK_FREQ_900MBPS,
>  };
> @@ -484,6 +496,9 @@ struct ov5675 {
>  	struct v4l2_subdev sd;
>  	struct media_pad pad;
>  	struct v4l2_ctrl_handler ctrl_handler;
> +	struct clk		*xvclk;
> +	struct gpio_desc	*reset_gpio;
> +	struct regulator_bulk_data supplies[OV5675_NUM_SUPPLIES];
>
>  	/* V4L2 Controls */
>  	struct v4l2_ctrl *link_freq;
> @@ -944,6 +959,56 @@ static int ov5675_set_stream(struct v4l2_subdev *sd, int enable)
>  	return ret;
>  }
>
> +static int ov5675_power_off(struct device *dev)

Does this (and power_on) require __maybe_unused to avoid a warning
when compiling without CONFIG_PM support ? Have you tried that ?

Thanks
  j

> +{
> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> +	struct ov5675 *ov5675 = to_ov5675(sd);
> +	/* 512 xvclk cycles after the last SCCB transation or MIPI frame end */
> +	u32 delay_us = DIV_ROUND_UP(512, OV5675_XVCLK_19_2 / 1000 / 1000);
> +
> +	usleep_range(delay_us, delay_us * 2);
> +
> +	clk_disable_unprepare(ov5675->xvclk);
> +	gpiod_set_value_cansleep(ov5675->reset_gpio, 1);
> +	regulator_bulk_disable(OV5675_NUM_SUPPLIES, ov5675->supplies);
> +
> +	return 0;
> +}
> +
> +static int ov5675_power_on(struct device *dev)
> +{
> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> +	struct ov5675 *ov5675 = to_ov5675(sd);
> +	u32 delay_us = DIV_ROUND_UP(8192, OV5675_XVCLK_19_2 / 1000 / 1000);
> +	int ret;
> +
> +	ret = clk_prepare_enable(ov5675->xvclk);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to enable xvclk: %d\n", ret);
> +		return ret;
> +	}
> +
> +	gpiod_set_value_cansleep(ov5675->reset_gpio, 1);
> +
> +	ret = regulator_bulk_enable(OV5675_NUM_SUPPLIES, ov5675->supplies);
> +	if (ret) {
> +		clk_disable_unprepare(ov5675->xvclk);
> +		return ret;
> +	}
> +
> +	/* Reset pulse should be at least 2ms and reset gpio released only once
> +	 * regulators are stable.
> +	 */
> +	usleep_range(2000, 2200);
> +
> +	gpiod_set_value_cansleep(ov5675->reset_gpio, 0);
> +
> +	/* 8192 xvclk cycles prior to the first SCCB transation */
> +	usleep_range(delay_us, delay_us * 2);
> +
> +	return 0;
> +}
> +
>  static int __maybe_unused ov5675_suspend(struct device *dev)
>  {
>  	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> @@ -1106,32 +1171,60 @@ static const struct v4l2_subdev_internal_ops ov5675_internal_ops = {
>  	.open = ov5675_open,
>  };
>
> -static int ov5675_check_hwcfg(struct device *dev)
> +static int ov5675_get_hwcfg(struct ov5675 *ov5675, struct device *dev)
>  {
>  	struct fwnode_handle *ep;
>  	struct fwnode_handle *fwnode = dev_fwnode(dev);
>  	struct v4l2_fwnode_endpoint bus_cfg = {
>  		.bus_type = V4L2_MBUS_CSI2_DPHY
>  	};
> -	u32 mclk;
> +	u32 xvclk_rate;
>  	int ret;
>  	unsigned int i, j;
>
>  	if (!fwnode)
>  		return -ENXIO;
>
> -	ret = fwnode_property_read_u32(fwnode, "clock-frequency", &mclk);
> +	ov5675->xvclk = devm_clk_get_optional(dev, NULL);
> +	if (IS_ERR(ov5675->xvclk))
> +		return dev_err_probe(dev, PTR_ERR(ov5675->xvclk),
> +				     "failed to get xvclk: %ld\n",
> +				     PTR_ERR(ov5675->xvclk));
>
> -	if (ret) {
> -		dev_err(dev, "can't get clock frequency");
> -		return ret;
> +	if (ov5675->xvclk) {
> +		xvclk_rate = clk_get_rate(ov5675->xvclk);
> +	} else {
> +		ret = fwnode_property_read_u32(fwnode, "clock-frequency",
> +					       &xvclk_rate);
> +
> +		if (ret) {
> +			dev_err(dev, "can't get clock frequency");
> +			return ret;
> +		}
>  	}
>
> -	if (mclk != OV5675_MCLK) {
> -		dev_err(dev, "external clock %d is not supported", mclk);
> +	if (xvclk_rate != OV5675_XVCLK_19_2) {
> +		dev_err(dev, "external clock rate %u is unsupported",
> +			xvclk_rate);
>  		return -EINVAL;
>  	}
>
> +	ov5675->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> +						     GPIOD_OUT_HIGH);
> +	if (IS_ERR(ov5675->reset_gpio)) {
> +		ret = PTR_ERR(ov5675->reset_gpio);
> +		dev_err(dev, "failed to get reset-gpios: %d\n", ret);
> +		return ret;
> +	}
> +
> +	for (i = 0; i < OV5675_NUM_SUPPLIES; i++)
> +		ov5675->supplies[i].supply = ov5675_supply_names[i];
> +
> +	ret = devm_regulator_bulk_get(dev, OV5675_NUM_SUPPLIES,
> +				      ov5675->supplies);
> +	if (ret)
> +		return ret;
> +
>  	ep = fwnode_graph_get_next_endpoint(fwnode, NULL);
>  	if (!ep)
>  		return -ENXIO;
> @@ -1186,6 +1279,9 @@ static int ov5675_remove(struct i2c_client *client)
>  	pm_runtime_disable(&client->dev);
>  	mutex_destroy(&ov5675->mutex);
>
> +	if (!pm_runtime_status_suspended(&client->dev))
> +		ov5675_power_off(&client->dev);
> +
>  	return 0;
>  }
>
> @@ -1195,25 +1291,31 @@ static int ov5675_probe(struct i2c_client *client)
>  	bool full_power;
>  	int ret;
>
> -	ret = ov5675_check_hwcfg(&client->dev);
> +	ov5675 = devm_kzalloc(&client->dev, sizeof(*ov5675), GFP_KERNEL);
> +	if (!ov5675)
> +		return -ENOMEM;
> +
> +	ret = ov5675_get_hwcfg(ov5675, &client->dev);
>  	if (ret) {
> -		dev_err(&client->dev, "failed to check HW configuration: %d",
> +		dev_err(&client->dev, "failed to get HW configuration: %d",
>  			ret);
>  		return ret;
>  	}
>
> -	ov5675 = devm_kzalloc(&client->dev, sizeof(*ov5675), GFP_KERNEL);
> -	if (!ov5675)
> -		return -ENOMEM;
> -
>  	v4l2_i2c_subdev_init(&ov5675->sd, client, &ov5675_subdev_ops);
>
> +	ret = ov5675_power_on(&client->dev);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to power on: %d\n", ret);
> +		return ret;
> +	}
> +
>  	full_power = acpi_dev_state_d0(&client->dev);
>  	if (full_power) {
>  		ret = ov5675_identify_module(ov5675);
>  		if (ret) {
>  			dev_err(&client->dev, "failed to find sensor: %d", ret);
> -			return ret;
> +			goto probe_power_off;
>  		}
>  	}
>
> @@ -1243,11 +1345,6 @@ static int ov5675_probe(struct i2c_client *client)
>  		goto probe_error_media_entity_cleanup;
>  	}
>
> -	/*
> -	 * Device is already turned on by i2c-core with ACPI domain PM.
> -	 * Enable runtime PM and turn off the device.
> -	 */
> -
>  	/* Set the device's state to active if it's in D0 state. */
>  	if (full_power)
>  		pm_runtime_set_active(&client->dev);
> @@ -1262,12 +1359,15 @@ static int ov5675_probe(struct i2c_client *client)
>  probe_error_v4l2_ctrl_handler_free:
>  	v4l2_ctrl_handler_free(ov5675->sd.ctrl_handler);
>  	mutex_destroy(&ov5675->mutex);
> +probe_power_off:
> +	ov5675_power_off(&client->dev);
>
>  	return ret;
>  }
>
>  static const struct dev_pm_ops ov5675_pm_ops = {
>  	SET_SYSTEM_SLEEP_PM_OPS(ov5675_suspend, ov5675_resume)
> +	SET_RUNTIME_PM_OPS(ov5675_power_off, ov5675_power_on, NULL)
>  };
>
>  #ifdef CONFIG_ACPI
> @@ -1279,11 +1379,18 @@ static const struct acpi_device_id ov5675_acpi_ids[] = {
>  MODULE_DEVICE_TABLE(acpi, ov5675_acpi_ids);
>  #endif
>
> +static const struct of_device_id ov5675_of_match[] = {
> +	{ .compatible = "ovti,ov5675", },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, ov5675_of_match);
> +
>  static struct i2c_driver ov5675_i2c_driver = {
>  	.driver = {
>  		.name = "ov5675",
>  		.pm = &ov5675_pm_ops,
>  		.acpi_match_table = ACPI_PTR(ov5675_acpi_ids),
> +		.of_match_table = ov5675_of_match,
>  	},
>  	.probe_new = ov5675_probe,
>  	.remove = ov5675_remove,
> --
> 2.36.1
>