Message-ID: <20200512181706.GA21014@Mani-XPS-13-9360>
Date:   Tue, 12 May 2020 23:47:06 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
Cc:     linux-renesas-soc@...r.kernel.org, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Kieran Bingham <kieran.bingham@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Jacopo Mondi <jacopo@...ndi.org>,
        Niklas Söderlund 
        <niklas.soderlund@...natech.se>, sakari.ailus@....fi,
        Hans Verkuil <hverkuil@...all.nl>,
        Hyun Kwon <hyunk@...inx.com>, Rob Herring <robh+dt@...nel.org>,
        Jacopo Mondi <jacopo+renesas@...ndi.org>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Niklas Söderlund 
        <niklas.soderlund+renesas@...natech.se>
Subject: Re: [PATCH v9 2/4] media: i2c: Add MAX9286 driver

On Tue, May 12, 2020 at 04:51:03PM +0100, Kieran Bingham wrote:
> The MAX9286 is a 4-channel GMSL deserializer with coax or STP input and
> CSI-2 output. The device supports multicamera streaming applications,
> and features the ability to synchronise the attached cameras.
> 
> CSI-2 output can be configured with 1 to 4 lanes, and a control channel
> is supported over I2C, which implements an I2C mux to facilitate
> communications with connected cameras across the reverse control
> channel.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
> 
> --
> v2:
>  - Fix MAINTAINERS entry
> 
> This posting is released with the following modifications to work
> without Sakari's VC developments:
>  - max9286_g_mbus_config() re-instated
>  - max9286_get_frame_desc() is not bus/csi aware
>  - max9286_{get,set}_routing() removed
> 
> v3:
>  - Initialise notifier with v4l2_async_notifier_init
>  - Update for new mbus csi2 format V4L2_MBUS_CSI2_DPHY
> 
> v4: - Re-introduce required code to function with the VC series.
> 
>  - Implement max9286_get_routing, max9286_set_routing
>  - Remove max9286_g_mbus_config
> 
> v5: (internal release)
>  - Fix printk formatting for hex value
>  - max9286->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE (add |)
>  - MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER -> MEDIA_ENT_F_VID_IF_BRIDGE
>  - Remove 'device is bound' workaround
> 
> v6:
>  - v4l2_subdev_krouting instead of v4l2_subdev_routing separated
>    to allow integration without the VC/V4L2-Mux series.
>  - convert sd_to_max9286 to inline function
>  - rename max9286_device to max9286_priv
>  - Cleanup the v4l2_async_notifier
>  - Extend MODULE_AUTHOR
>  - Replace of_graph_get_endpoint_by_regs with fwnode_graph_get_endpoint_by_id
>  - Pass default bus type when parsing fwnode endpoint (Manivannan Sadhasivam)
>  - Use new YAML file reference in MAINTAINERS
>  - Parse new i2c-mux node in max9286_get_i2c_by_id
>    (This could/should be refactored to parse these separately first)
>  - Spelling and calculation fixes in the FSYNC_LOCKED check comments
>  - Identify each enabled i2c-mux channel in a single pass
>  - max9286: Improve mux-state readbility [v2]
>  - Fix frame sync lock durations
>  - Add comment to describe /why/ we must open the mux in s_stream
>  - use -EXDEV as return code for failed link synchronisation.
>  - Fix reference counting of the dt nodeS
>  - Convert to probe_new for I2C
>  - Remove redundant max9286_i2c_mux_state
>  - Provide optional enable-gpio (max9286-pwdn)
> 
> v7:
>  [Kieran]
>  - Ensure powerdown lines are optional
>  - Add a 4ms power-up delay
>  - Add max9286_check_config_link() to core
>  - Add GPIO chip controller for GPIO0OUT and GPIO1OUT
>  - Fix GPIO registration
>  - max9286: Split out async registration
>    (fixes regulator -EPROBE_DEFERs failures)
>  - Collect all V4L2 registrations
>  - balance v4l2_async refcnting
>  - Rename max9286_v4l2_async_ => max9286_v4l2_notifier_
> 
>  [Jacopo]
>  - Remove redundanct MAXIM_I2C_SPEED macros
>  - Move notifiers operations
>  - Add delay after reverse channel reconfiguration
>  - Move link setup to completion
>  - Fix up max9286_check_config_link() implementation
>  - Remove redundant dual configuration of reverse channel
> 
> v8:
> 
> [Kieran]
>  - Update the bound_sources mask on unbind
>  - Convert probe kzalloc usage to devm_ variant
>  - Fix up cleanup path from GPIO PowerDown registration
>  - cleanup GPIO device registration fail path
>  - Convert to use devm_regulator_get()
>  - Fit max9286_parse_dt print on one line
>  - Move multi-device workarounds out of upstream driver
>  - Remove I2C mod-table
>  - Lock format changes
>  - Describe pad index usage
>  - Remove poc_enabled workaround
>  - Rename the max9286_gpio to be more explicit on it's actions.
>  - Move max9286_init_format call
>  - Rework probe sequence and simplify error paths.
>  - Simplify i2c comments
>  - Implement Pixelrate control
>  - Disable overlap window
> 
> [Jacopo]
>  - Adapt Kconfig to latest upstream changes
>  - Put of node on error
>  - Calculate pixel rate
>  - Simplify overlap window disablement
> 
> v9:
> 
> [Kieran]
>  - Kconfig: Depend on OF
>  - Re-sort addition to Makefile
> ---
>  MAINTAINERS                 |   10 +
>  drivers/media/i2c/Kconfig   |   13 +
>  drivers/media/i2c/Makefile  |    1 +
>  drivers/media/i2c/max9286.c | 1332 +++++++++++++++++++++++++++++++++++
>  4 files changed, 1356 insertions(+)
>  create mode 100644 drivers/media/i2c/max9286.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a7bb6e22d5da..99e3bf7760fd 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10274,6 +10274,16 @@ F:	Documentation/hwmon/max6697.rst
>  F:	drivers/hwmon/max6697.c
>  F:	include/linux/platform_data/max6697.h
>  
> +MAX9286 QUAD GMSL DESERIALIZER DRIVER
> +M:	Jacopo Mondi <jacopo+renesas@...ndi.org>
> +M:	Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> +M:	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
> +M:	Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
> +L:	linux-media@...r.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> +F:	drivers/media/i2c/max9286.c
> +
>  MAX9860 MONO AUDIO VOICE CODEC DRIVER
>  M:	Peter Rosin <peda@...ntia.se>
>  L:	alsa-devel@...a-project.org (moderated for non-subscribers)
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 3abc80373ec0..2e390f41f6da 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -464,6 +464,19 @@ config VIDEO_VPX3220
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called vpx3220.
>  
> +config VIDEO_MAX9286
> +	tristate "Maxim MAX9286 GMSL deserializer support"
> +	depends on I2C && I2C_MUX
> +	depends on OF
> +	select V4L2_FWNODE
> +	select VIDEO_V4L2_SUBDEV_API
> +	select MEDIA_CONTROLLER
> +	help
> +	  This driver supports the Maxim MAX9286 GMSL deserializer.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called max9286.
> +
>  comment "Video and audio decoders"
>  
>  config VIDEO_SAA717X
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 77bf7d0b691f..f0b001ee4b05 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -117,6 +117,7 @@ obj-$(CONFIG_VIDEO_IMX274)	+= imx274.o
>  obj-$(CONFIG_VIDEO_IMX290)	+= imx290.o
>  obj-$(CONFIG_VIDEO_IMX319)	+= imx319.o
>  obj-$(CONFIG_VIDEO_IMX355)	+= imx355.o
> +obj-$(CONFIG_VIDEO_MAX9286)	+= max9286.o
>  obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
>  
>  obj-$(CONFIG_SDR_MAX2175) += max2175.o
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> new file mode 100644
> index 000000000000..481d65f2b51d
> --- /dev/null
> +++ b/drivers/media/i2c/max9286.c
> @@ -0,0 +1,1332 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Maxim MAX9286 GMSL Deserializer Driver
> + *
> + * Copyright (C) 2017-2019 Jacopo Mondi
> + * Copyright (C) 2017-2019 Kieran Bingham
> + * Copyright (C) 2017-2019 Laurent Pinchart
> + * Copyright (C) 2017-2019 Niklas Söderlund
> + * Copyright (C) 2016 Renesas Electronics Corporation
> + * Copyright (C) 2015 Cogent Embedded, Inc.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/fwnode.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/i2c.h>
> +#include <linux/i2c-mux.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_graph.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#include <media/v4l2-async.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +/* Register 0x00 */
> +#define MAX9286_MSTLINKSEL_AUTO		(7 << 5)
> +#define MAX9286_MSTLINKSEL(n)		((n) << 5)
> +#define MAX9286_EN_VS_GEN		BIT(4)
> +#define MAX9286_LINKEN(n)		(1 << (n))
> +/* Register 0x01 */
> +#define MAX9286_FSYNCMODE_ECU		(3 << 6)
> +#define MAX9286_FSYNCMODE_EXT		(2 << 6)
> +#define MAX9286_FSYNCMODE_INT_OUT	(1 << 6)
> +#define MAX9286_FSYNCMODE_INT_HIZ	(0 << 6)
> +#define MAX9286_GPIEN			BIT(5)
> +#define MAX9286_ENLMO_RSTFSYNC		BIT(2)
> +#define MAX9286_FSYNCMETH_AUTO		(2 << 0)
> +#define MAX9286_FSYNCMETH_SEMI_AUTO	(1 << 0)
> +#define MAX9286_FSYNCMETH_MANUAL	(0 << 0)
> +#define MAX9286_REG_FSYNC_PERIOD_L	0x06
> +#define MAX9286_REG_FSYNC_PERIOD_M	0x07
> +#define MAX9286_REG_FSYNC_PERIOD_H	0x08
> +/* Register 0x0a */
> +#define MAX9286_FWDCCEN(n)		(1 << ((n) + 4))
> +#define MAX9286_REVCCEN(n)		(1 << (n))
> +/* Register 0x0c */
> +#define MAX9286_HVEN			BIT(7)
> +#define MAX9286_EDC_6BIT_HAMMING	(2 << 5)
> +#define MAX9286_EDC_6BIT_CRC		(1 << 5)
> +#define MAX9286_EDC_1BIT_PARITY		(0 << 5)
> +#define MAX9286_DESEL			BIT(4)
> +#define MAX9286_INVVS			BIT(3)
> +#define MAX9286_INVHS			BIT(2)
> +#define MAX9286_HVSRC_D0		(2 << 0)
> +#define MAX9286_HVSRC_D14		(1 << 0)
> +#define MAX9286_HVSRC_D18		(0 << 0)
> +/* Register 0x0f */
> +#define MAX9286_0X0F_RESERVED		BIT(3)
> +/* Register 0x12 */
> +#define MAX9286_CSILANECNT(n)		(((n) - 1) << 6)
> +#define MAX9286_CSIDBL			BIT(5)
> +#define MAX9286_DBL			BIT(4)
> +#define MAX9286_DATATYPE_USER_8BIT	(11 << 0)
> +#define MAX9286_DATATYPE_USER_YUV_12BIT	(10 << 0)
> +#define MAX9286_DATATYPE_USER_24BIT	(9 << 0)
> +#define MAX9286_DATATYPE_RAW14		(8 << 0)
> +#define MAX9286_DATATYPE_RAW11		(7 << 0)
> +#define MAX9286_DATATYPE_RAW10		(6 << 0)
> +#define MAX9286_DATATYPE_RAW8		(5 << 0)
> +#define MAX9286_DATATYPE_YUV422_10BIT	(4 << 0)
> +#define MAX9286_DATATYPE_YUV422_8BIT	(3 << 0)
> +#define MAX9286_DATATYPE_RGB555		(2 << 0)
> +#define MAX9286_DATATYPE_RGB565		(1 << 0)
> +#define MAX9286_DATATYPE_RGB888		(0 << 0)
> +/* Register 0x15 */
> +#define MAX9286_VC(n)			((n) << 5)
> +#define MAX9286_VCTYPE			BIT(4)
> +#define MAX9286_CSIOUTEN		BIT(3)
> +#define MAX9286_0X15_RESV		(3 << 0)
> +/* Register 0x1b */
> +#define MAX9286_SWITCHIN(n)		(1 << ((n) + 4))
> +#define MAX9286_ENEQ(n)			(1 << (n))
> +/* Register 0x27 */
> +#define MAX9286_LOCKED			BIT(7)
> +/* Register 0x31 */
> +#define MAX9286_FSYNC_LOCKED		BIT(6)
> +/* Register 0x34 */
> +#define MAX9286_I2CLOCACK		BIT(7)
> +#define MAX9286_I2CSLVSH_1046NS_469NS	(3 << 5)
> +#define MAX9286_I2CSLVSH_938NS_352NS	(2 << 5)
> +#define MAX9286_I2CSLVSH_469NS_234NS	(1 << 5)
> +#define MAX9286_I2CSLVSH_352NS_117NS	(0 << 5)
> +#define MAX9286_I2CMSTBT_837KBPS	(7 << 2)
> +#define MAX9286_I2CMSTBT_533KBPS	(6 << 2)
> +#define MAX9286_I2CMSTBT_339KBPS	(5 << 2)
> +#define MAX9286_I2CMSTBT_173KBPS	(4 << 2)
> +#define MAX9286_I2CMSTBT_105KBPS	(3 << 2)
> +#define MAX9286_I2CMSTBT_84KBPS		(2 << 2)
> +#define MAX9286_I2CMSTBT_28KBPS		(1 << 2)
> +#define MAX9286_I2CMSTBT_8KBPS		(0 << 2)
> +#define MAX9286_I2CSLVTO_NONE		(3 << 0)
> +#define MAX9286_I2CSLVTO_1024US		(2 << 0)
> +#define MAX9286_I2CSLVTO_256US		(1 << 0)
> +#define MAX9286_I2CSLVTO_64US		(0 << 0)
> +/* Register 0x3b */
> +#define MAX9286_REV_TRF(n)		((n) << 4)
> +#define MAX9286_REV_AMP(n)		((((n) - 30) / 10) << 1) /* in mV */
> +#define MAX9286_REV_AMP_X		BIT(0)
> +/* Register 0x3f */
> +#define MAX9286_EN_REV_CFG		BIT(6)
> +#define MAX9286_REV_FLEN(n)		((n) - 20)
> +/* Register 0x49 */
> +#define MAX9286_VIDEO_DETECT_MASK	0x0f
> +/* Register 0x69 */
> +#define MAX9286_LFLTBMONMASKED		BIT(7)
> +#define MAX9286_LOCKMONMASKED		BIT(6)
> +#define MAX9286_AUTOCOMBACKEN		BIT(5)
> +#define MAX9286_AUTOMASKEN		BIT(4)
> +#define MAX9286_MASKLINK(n)		((n) << 0)
> +
> +/*
> + * The sink and source pads are created to match the OF graph port numbers so
> + * that their indexes can be used interchangeably.
> + */
> +#define MAX9286_NUM_GMSL		4
> +#define MAX9286_N_SINKS			4
> +#define MAX9286_N_PADS			5
> +#define MAX9286_SRC_PAD			4
> +
> +struct max9286_source {
> +	struct v4l2_async_subdev asd;
> +	struct v4l2_subdev *sd;
> +	struct fwnode_handle *fwnode;
> +};
> +
> +#define asd_to_max9286_source(_asd) \
> +	container_of(_asd, struct max9286_source, asd)
> +
> +struct max9286_priv {
> +	struct i2c_client *client;
> +	struct gpio_desc *gpiod_pwdn;
> +	struct v4l2_subdev sd;
> +	struct media_pad pads[MAX9286_N_PADS];
> +	struct regulator *regulator;
> +
> +	struct gpio_chip gpio;
> +	u8 gpio_state;
> +
> +	struct i2c_mux_core *mux;
> +	unsigned int mux_channel;
> +	bool mux_open;
> +
> +	struct v4l2_ctrl_handler ctrls;
> +	struct v4l2_ctrl *pixelrate;
> +
> +	struct v4l2_mbus_framefmt fmt[MAX9286_N_SINKS];
> +
> +	/* Protects controls and fmt structures */
> +	struct mutex mutex;
> +
> +	unsigned int nsources;
> +	unsigned int source_mask;
> +	unsigned int route_mask;
> +	unsigned int bound_sources;
> +	unsigned int csi2_data_lanes;
> +	struct max9286_source sources[MAX9286_NUM_GMSL];
> +	struct v4l2_async_notifier notifier;
> +};
> +

[...]

> +static int max9286_register_gpio(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct gpio_chip *gpio = &priv->gpio;
> +	int ret;
> +
> +	static const char * const names[] = {
> +		"GPIO0OUT",
> +		"GPIO1OUT",
> +	};
> +
> +	/* Configure the GPIO */
> +	gpio->label = dev_name(dev);

So if you have more than one MAX9286 in a system, all gpiochips will appear
with the same name. I'd recommend to append the index to distinguish properly.

> +	gpio->parent = dev;
> +	gpio->owner = THIS_MODULE;
> +	gpio->of_node = dev->of_node;
> +	gpio->ngpio = 2;
> +	gpio->base = -1;
> +	gpio->set = max9286_gpio_set;
> +	gpio->get = max9286_gpio_get;
> +	gpio->can_sleep = true;
> +	gpio->names = names;
> +
> +	/* GPIO values default to high */
> +	priv->gpio_state = BIT(0) | BIT(1);
> +
> +	ret = devm_gpiochip_add_data(dev, gpio, priv);
> +	if (ret)
> +		dev_err(dev, "Unable to create gpio_chip\n");
> +
> +	return ret;
> +}
> +

[...]

> +static int max9286_parse_dt(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct device_node *i2c_mux;
> +	struct device_node *node = NULL;
> +	unsigned int i2c_mux_mask = 0;
> +
> +	of_node_get(dev->of_node);

Why this is needed?

> +	i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
> +	if (!i2c_mux) {
> +		dev_err(dev, "Failed to find i2c-mux node\n");
> +		of_node_put(dev->of_node);
> +		return -EINVAL;
> +	}
> +
> +	/* Identify which i2c-mux channels are enabled */
> +	for_each_child_of_node(i2c_mux, node) {
> +		u32 id = 0;
> +
> +		of_property_read_u32(node, "reg", &id);
> +		if (id >= MAX9286_NUM_GMSL)
> +			continue;
> +
> +		if (!of_device_is_available(node)) {
> +			dev_dbg(dev, "Skipping disabled I2C bus port %u\n", id);
> +			continue;
> +		}
> +
> +		i2c_mux_mask |= BIT(id);
> +	}
> +	of_node_put(node);
> +	of_node_put(i2c_mux);
> +
> +	/* Parse the endpoints */
> +	for_each_endpoint_of_node(dev->of_node, node) {
> +		struct max9286_source *source;
> +		struct of_endpoint ep;
> +
> +		of_graph_parse_endpoint(node, &ep);
> +		dev_dbg(dev, "Endpoint %pOF on port %d",
> +			ep.local_node, ep.port);
> +
> +		if (ep.port > MAX9286_NUM_GMSL) {
> +			dev_err(dev, "Invalid endpoint %s on port %d",
> +				of_node_full_name(ep.local_node), ep.port);
> +			continue;
> +		}
> +
> +		/* For the source endpoint just parse the bus configuration. */
> +		if (ep.port == MAX9286_SRC_PAD) {
> +			struct v4l2_fwnode_endpoint vep = {
> +				.bus_type = V4L2_MBUS_CSI2_DPHY
> +			};
> +			int ret;
> +
> +			ret = v4l2_fwnode_endpoint_parse(
> +					of_fwnode_handle(node), &vep);
> +			if (ret) {
> +				of_node_put(node);
> +				of_node_put(dev->of_node);
> +				return ret;
> +			}
> +
> +			if (vep.bus_type != V4L2_MBUS_CSI2_DPHY) {
> +				dev_err(dev,
> +					"Media bus %u type not supported\n",
> +					vep.bus_type);
> +				v4l2_fwnode_endpoint_free(&vep);
> +				of_node_put(node);
> +				of_node_put(dev->of_node);
> +				return -EINVAL;
> +			}
> +
> +			priv->csi2_data_lanes =
> +				vep.bus.mipi_csi2.num_data_lanes;
> +			v4l2_fwnode_endpoint_free(&vep);
> +
> +			continue;
> +		}
> +
> +		/* Skip if the corresponding GMSL link is unavailable. */
> +		if (!(i2c_mux_mask & BIT(ep.port)))
> +			continue;
> +
> +		if (priv->sources[ep.port].fwnode) {
> +			dev_err(dev,
> +				"Multiple port endpoints are not supported: %d",
> +				ep.port);
> +
> +			continue;
> +		}
> +
> +		source = &priv->sources[ep.port];
> +		source->fwnode = fwnode_graph_get_remote_endpoint(
> +						of_fwnode_handle(node));
> +		if (!source->fwnode) {
> +			dev_err(dev,
> +				"Endpoint %pOF has no remote endpoint connection\n",
> +				ep.local_node);
> +
> +			continue;
> +		}
> +
> +		priv->source_mask |= BIT(ep.port);
> +		priv->nsources++;
> +	}
> +	of_node_put(node);
> +	of_node_put(dev->of_node);
> +
> +	priv->route_mask = priv->source_mask;
> +
> +	return 0;
> +}
> +

[...]

> +static int max9286_remove(struct i2c_client *client)
> +{
> +	struct max9286_priv *priv = i2c_get_clientdata(client);
> +
> +	i2c_mux_del_adapters(priv->mux);
> +
> +	max9286_v4l2_unregister(priv);
> +
> +	regulator_disable(priv->regulator);
> +
> +	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);

Usual power down sequence is to pull the power down gpio low and then turn off
the regulators. This helps in clearing up the internal state machine properly.

Thanks,
Mani

> +
> +	max9286_cleanup_dt(priv);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id max9286_dt_ids[] = {
> +	{ .compatible = "maxim,max9286" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, max9286_dt_ids);
> +
> +static struct i2c_driver max9286_i2c_driver = {
> +	.driver	= {
> +		.name		= "max9286",
> +		.of_match_table	= of_match_ptr(max9286_dt_ids),
> +	},
> +	.probe_new	= max9286_probe,
> +	.remove		= max9286_remove,
> +};
> +
> +module_i2c_driver(max9286_i2c_driver);
> +
> +MODULE_DESCRIPTION("Maxim MAX9286 GMSL Deserializer Driver");
> +MODULE_AUTHOR("Jacopo Mondi, Kieran Bingham, Laurent Pinchart, Niklas Söderlund, Vladimir Barinov");
> +MODULE_LICENSE("GPL");
> -- 
> 2.25.1
> 

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