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Date:   Thu, 14 May 2020 15:43:56 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Cc:     linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Kieran Bingham <kieran.bingham@ideasonboard.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Jacopo Mondi <jacopo@jmondi.org>,
        Niklas =?iso-8859-1?Q?S=F6derlund?= 
        <niklas.soderlund@ragnatech.se>, sakari.ailus@iki.fi,
        Hans Verkuil <hverkuil@xs4all.nl>,
        Hyun Kwon <hyunk@xilinx.com>, Rob Herring <robh+dt@kernel.org>,
        Jacopo Mondi <jacopo+renesas@jmondi.org>,
        Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
        Niklas =?iso-8859-1?Q?S=F6derlund?= 
        <niklas.soderlund+renesas@ragnatech.se>
Subject: Re: [PATCH v9 2/4] media: i2c: Add MAX9286 driver
Message-ID: <20200514101356.GF2877@Mani-XPS-13-9360>
References: <20200512155105.1068064-1-kieran.bingham+renesas@ideasonboard.com>
 <20200512155105.1068064-3-kieran.bingham+renesas@ideasonboard.com>
 <20200512181706.GA21014@Mani-XPS-13-9360>
 <11aca587-9438-4fba-081c-b82631e96989@ideasonboard.com>
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Hi Kieran,

On Thu, May 14, 2020 at 11:02:53AM +0100, Kieran Bingham wrote:
> Hi Mani,
> 
> On 12/05/2020 19:17, Manivannan Sadhasivam wrote:
> > 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@jmondi.org>
> >> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> >> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> >> Signed-off-by: Niklas S?derlund <niklas.soderlund+renesas@ragnatech.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@jmondi.org>
> >> +M:	Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> >> +M:	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> >> +M:	Niklas S?derlund <niklas.soderlund+renesas@ragnatech.se>
> >> +L:	linux-media@vger.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@axentia.se>
> >>  L:	alsa-devel@alsa-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 S?derlund
> >> + * 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.
> 
> Ah yes, that's a good point, and I think I've even seen that.
> 
> I'll fix it now.
> 
> > 
> >> +	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?
> 
> Hrm .. I recall adding it to solve dt reference balancing.
> 
> I wish I'd added a comment at the time ... as I can't recall the details
> now.
>

I understand that it is for the refcount balancing but I certainly don't see
a need for it.
 
> >> +	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;
> >> +	}
> >> +
[...]
> > 
> > [...]
> > 
> >> +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.
> 
> Do you mean usual, among drivers using regulators? or usual for the max9286?
> 

Usual for devices exposing shutdown gpios and powered by an external regulator.

> I have a platform which controls the regulators for the cameras
> (priv->regulator) through one of the GPIOs provided by the MAX9286.
> 
> If we powerdown the max9286 first, then we will not be able to change
> the GPIO value on the gpio controlled regulator.
> 

Hmm, I didn't think of this usecase. Let's keep it as it is.

Thanks,
Mani

> (Currently it doesn't expose as a gpio regulator, but just a gpio-hog -
> but thats a different matter)
> 
> --
> Kieran
> 
> 
> > 
> > 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 S?derlund, Vladimir Barinov");
> >> +MODULE_LICENSE("GPL");
> >> -- 
> >> 2.25.1
> >>
>