Re: [PATCH v2 2/2] media: i2c: IMX296 camera sensor driver

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Laurent,

Thanks for the patchset. A few relatively minor comments below.

On Mon, Dec 20, 2021 at 12:09:48AM +0200, Laurent Pinchart wrote:
> The IMX296LLR is a monochrome 1.60MP CMOS sensor from Sony. The driver
> supports cropping and binning (but not both at the same time due to
> hardware limitations) and exposure, gain, vertical blanking and test
> pattern controls.
> 
> Preliminary support is also included for the color IMX296LQR sensor.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
> Changes since v1:
> 
> - Use help instead of ---help--- in Kconfig
> - Print error message on I2C write failure
> - Fix number of controls in v4l2_ctrl_handler_init() call
> - Replace hardcoded number with ARRAY_SIZE()
> - Initialize structures at declaration time
> - Use .probe_new() and remove I2C device table
> - Drop of_match_ptr()
> - Fix module description
> - Fix test pattern configuration
> - Fix power on
> - Read sensor temperature at probe time
> - Set opaque background in test patterns
> - Initialize format field and colorspace
> - Reorder subdev pad operations
> - Create controls for fwnode properties
> - Expose crop bounds and defaults
> - Add V4L2_CID_HBLANK control
> - Replace gain control with analogue gain
> - Rename local variable 'imx' to 'sensor'
> - Protect format and crop with a mutex
> - Consistently access struct device through sensor->dev
> - Use runtime PM
> - Use three power supplies
> - Fix number of controls when initializing handler
> - Fix error message for reset GPIO get failure
> - Switch to V4L2 subdev state API
> - Use dev_err_probe()
> ---
>  MAINTAINERS                |    1 +
>  drivers/media/i2c/Kconfig  |   12 +
>  drivers/media/i2c/Makefile |    1 +
>  drivers/media/i2c/imx296.c | 1200 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 1214 insertions(+)
>  create mode 100644 drivers/media/i2c/imx296.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1b20f2b90aec..e49049e8ee36 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17759,6 +17759,7 @@ L:	linux-media@vger.kernel.org
>  S:	Maintained
>  T:	git git://linuxtv.org/media_tree.git
>  F:	Documentation/devicetree/bindings/media/i2c/sony,imx296.yaml
> +F:	drivers/media/i2c/imx296.c
>  
>  SONY IMX319 SENSOR DRIVER
>  M:	Bingbu Cao <bingbu.cao@intel.com>
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index d6a5d4ca439a..8cc23019459d 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -832,6 +832,18 @@ config VIDEO_IMX290
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called imx290.
>  
> +config VIDEO_IMX296
> +	tristate "Sony IMX296 sensor support"
> +	depends on I2C && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
> +	depends on MEDIA_CAMERA_SUPPORT
> +	select V4L2_FWNODE
> +	help
> +	  This is a Video4Linux2 sensor driver for the Sony
> +	  IMX296 camera.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called imx296.
> +
>  config VIDEO_IMX319
>  	tristate "Sony IMX319 sensor support"
>  	depends on I2C && VIDEO_V4L2
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 4d4fe08d7a6a..aba3bd7dd337 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -125,6 +125,7 @@ obj-$(CONFIG_VIDEO_IMX219)	+= imx219.o
>  obj-$(CONFIG_VIDEO_IMX258)	+= imx258.o
>  obj-$(CONFIG_VIDEO_IMX274)	+= imx274.o
>  obj-$(CONFIG_VIDEO_IMX290)	+= imx290.o
> +obj-$(CONFIG_VIDEO_IMX296)	+= imx296.o
>  obj-$(CONFIG_VIDEO_IMX319)	+= imx319.o
>  obj-$(CONFIG_VIDEO_IMX334)	+= imx334.o
>  obj-$(CONFIG_VIDEO_IMX335)	+= imx335.o
> diff --git a/drivers/media/i2c/imx296.c b/drivers/media/i2c/imx296.c
> new file mode 100644
> index 000000000000..4be03180deac
> --- /dev/null
> +++ b/drivers/media/i2c/imx296.c
> @@ -0,0 +1,1200 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for IMX296 CMOS Image Sensor from Sony
> + *
> + * Copyright 2019 Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +#include <linux/videodev2.h>
> +
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +#define IMX296_PIXEL_ARRAY_WIDTH			1456
> +#define IMX296_PIXEL_ARRAY_HEIGHT			1088
> +
> +#define IMX296_REG_8BIT(n)				((1 << 16) | (n))
> +#define IMX296_REG_16BIT(n)				((2 << 16) | (n))
> +#define IMX296_REG_24BIT(n)				((3 << 16) | (n))
> +#define IMX296_REG_SIZE_SHIFT				16
> +#define IMX296_REG_ADDR_MASK				0xffff
> +
> +#define IMX296_CTRL00					IMX296_REG_8BIT(0x3000)
> +#define IMX296_CTRL00_STANDBY				BIT(0)
> +#define IMX296_CTRL08					IMX296_REG_8BIT(0x3008)
> +#define IMX296_CTRL08_REGHOLD				BIT(0)
> +#define IMX296_CTRL0A					IMX296_REG_8BIT(0x300a)
> +#define IMX296_CTRL0A_XMSTA				BIT(0)
> +#define IMX296_CTRL0B					IMX296_REG_8BIT(0x300b)
> +#define IMX296_CTRL0B_TRIGEN				BIT(0)
> +#define IMX296_CTRL0D					IMX296_REG_8BIT(0x300d)
> +#define IMX296_CTRL0D_WINMODE_ALL			(0 << 0)
> +#define IMX296_CTRL0D_WINMODE_FD_BINNING		(2 << 0)
> +#define IMX296_CTRL0D_HADD_ON_BINNING			BIT(5)
> +#define IMX296_CTRL0D_SAT_CNT				BIT(6)
> +#define IMX296_CTRL0E					IMX296_REG_8BIT(0x300e)
> +#define IMX296_CTRL0E_VREVERSE				BIT(0)
> +#define IMX296_CTRL0E_HREVERSE				BIT(1)
> +#define IMX296_VMAX					IMX296_REG_24BIT(0x3010)
> +#define IMX296_HMAX					IMX296_REG_16BIT(0x3014)
> +#define IMX296_TMDCTRL					IMX296_REG_8BIT(0x301d)
> +#define IMX296_TMDCTRL_LATCH				BIT(0)
> +#define IMX296_TMDOUT					IMX296_REG_16BIT(0x301e)
> +#define IMX296_TMDOUT_MASK				0x3ff
> +#define IMX296_WDSEL					IMX296_REG_8BIT(0x3021)
> +#define IMX296_WDSEL_NORMAL				(0 << 0)
> +#define IMX296_WDSEL_MULTI_2				(1 << 0)
> +#define IMX296_WDSEL_MULTI_4				(3 << 0)
> +#define IMX296_BLKLEVELAUTO				IMX296_REG_8BIT(0x3022)
> +#define IMX296_BLKLEVELAUTO_ON				0x01
> +#define IMX296_BLKLEVELAUTO_OFF				0xf0
> +#define IMX296_SST					IMX296_REG_8BIT(0x3024)
> +#define IMX296_SST_EN					BIT(0)
> +#define IMX296_CTRLTOUT					IMX296_REG_8BIT(0x3026)
> +#define IMX296_CTRLTOUT_TOUT1SEL_LOW			(0 << 0)
> +#define IMX296_CTRLTOUT_TOUT1SEL_PULSE			(3 << 0)
> +#define IMX296_CTRLTOUT_TOUT2SEL_LOW			(0 << 2)
> +#define IMX296_CTRLTOUT_TOUT2SEL_PULSE			(3 << 2)
> +#define IMX296_CTRLTRIG					IMX296_REG_8BIT(0x3029)
> +#define IMX296_CTRLTRIG_TOUT1_SEL_LOW			(0 << 0)
> +#define IMX296_CTRLTRIG_TOUT1_SEL_PULSE1		(1 << 0)
> +#define IMX296_CTRLTRIG_TOUT2_SEL_LOW			(0 << 4)
> +#define IMX296_CTRLTRIG_TOUT2_SEL_PULSE2		(2 << 4)
> +#define IMX296_SYNCSEL					IMX296_REG_8BIT(0x3036)
> +#define IMX296_SYNCSEL_NORMAL				0xc0
> +#define IMX296_SYNCSEL_HIZ				0xf0
> +#define IMX296_PULSE1					IMX296_REG_8BIT(0x306d)
> +#define IMX296_PULSE1_EN_NOR				BIT(0)
> +#define IMX296_PULSE1_EN_TRIG				BIT(1)
> +#define IMX296_PULSE1_POL_HIGH				(0 << 2)
> +#define IMX296_PULSE1_POL_LOW				(1 << 2)
> +#define IMX296_PULSE1_UP				IMX296_REG_24BIT(0x3070)
> +#define IMX296_PULSE1_DN				IMX296_REG_24BIT(0x3074)
> +#define IMX296_PULSE2					IMX296_REG_8BIT(0x3079)
> +#define IMX296_PULSE2_EN_NOR				BIT(0)
> +#define IMX296_PULSE2_EN_TRIG				BIT(1)
> +#define IMX296_PULSE2_POL_HIGH				(0 << 2)
> +#define IMX296_PULSE2_POL_LOW				(1 << 2)
> +#define IMX296_PULSE2_UP				IMX296_REG_24BIT(0x307c)
> +#define IMX296_PULSE2_DN				IMX296_REG_24BIT(0x3080)
> +#define IMX296_INCKSEL(n)				IMX296_REG_8BIT(0x3089 + (n))
> +#define IMX296_SHS1					IMX296_REG_24BIT(0x308d)
> +#define IMX296_SHS2					IMX296_REG_24BIT(0x3090)
> +#define IMX296_SHS3					IMX296_REG_24BIT(0x3094)
> +#define IMX296_SHS4					IMX296_REG_24BIT(0x3098)
> +#define IMX296_VBLANKLP					IMX296_REG_8BIT(0x309c)
> +#define IMX296_VBLANKLP_NORMAL				0x04
> +#define IMX296_VBLANKLP_LOW_POWER			0x2c
> +#define IMX296_EXP_CNT					IMX296_REG_8BIT(0x30a3)
> +#define IMX296_EXP_CNT_RESET				BIT(0)
> +#define IMX296_EXP_MAX					IMX296_REG_16BIT(0x30a6)
> +#define IMX296_VINT					IMX296_REG_8BIT(0x30aa)
> +#define IMX296_VINT_EN					BIT(0)
> +#define IMX296_LOWLAGTRG				IMX296_REG_8BIT(0x30ae)
> +#define IMX296_LOWLAGTRG_FAST				BIT(0)
> +#define IMX296_I2CCTRL					IMX296_REG_8BIT(0x30ef)
> +#define IMX296_I2CCTRL_I2CACKEN				BIT(0)
> +
> +#define IMX296_SENSOR_INFO				IMX296_REG_16BIT(0x3148)
> +#define IMX296_SENSOR_INFO_MONO				BIT(15)
> +#define IMX296_S_SHSA					IMX296_REG_16BIT(0x31ca)
> +#define IMX296_S_SHSB					IMX296_REG_16BIT(0x31d2)
> +/*
> + * Registers 0x31c8 to 0x31cd, 0x31d0 to 0x31d5, 0x31e2, 0x31e3, 0x31ea and
> + * 0x31eb are related to exposure mode but otherwise not documented.
> + */
> +
> +#define IMX296_GAINCTRL					IMX296_REG_8BIT(0x3200)
> +#define IMX296_GAINCTRL_WD_GAIN_MODE_NORMAL		0x01
> +#define IMX296_GAINCTRL_WD_GAIN_MODE_MULTI		0x41
> +#define IMX296_GAIN					IMX296_REG_16BIT(0x3204)
> +#define IMX296_GAIN_MIN					0
> +#define IMX296_GAIN_MAX					480
> +#define IMX296_GAIN1					IMX296_REG_16BIT(0x3208)
> +#define IMX296_GAIN2					IMX296_REG_16BIT(0x320c)
> +#define IMX296_GAIN3					IMX296_REG_16BIT(0x3210)
> +#define IMX296_GAINDLY					IMX296_REG_8BIT(0x3212)
> +#define IMX296_GAINDLY_NONE				0x08
> +#define IMX296_GAINDLY_1FRAME				0x09
> +#define IMX296_PGCTRL					IMX296_REG_8BIT(0x3238)
> +#define IMX296_PGCTRL_REGEN				BIT(0)
> +#define IMX296_PGCTRL_THRU				BIT(1)
> +#define IMX296_PGCTRL_CLKEN				BIT(2)
> +#define IMX296_PGCTRL_MODE(n)				((n) << 3)
> +#define IMX296_PGHPOS					IMX296_REG_16BIT(0x3239)
> +#define IMX296_PGVPOS					IMX296_REG_16BIT(0x323c)
> +#define IMX296_PGHPSTEP					IMX296_REG_8BIT(0x323e)
> +#define IMX296_PGVPSTEP					IMX296_REG_8BIT(0x323f)
> +#define IMX296_PGHPNUM					IMX296_REG_8BIT(0x3240)
> +#define IMX296_PGVPNUM					IMX296_REG_8BIT(0x3241)
> +#define IMX296_PGDATA1					IMX296_REG_16BIT(0x3244)
> +#define IMX296_PGDATA2					IMX296_REG_16BIT(0x3246)
> +#define IMX296_PGHGSTEP					IMX296_REG_8BIT(0x3249)
> +#define IMX296_BLKLEVEL					IMX296_REG_16BIT(0x3254)
> +
> +#define IMX296_FID0_ROI					IMX296_REG_8BIT(0x3300)
> +#define IMX296_FID0_ROIH1ON				BIT(0)
> +#define IMX296_FID0_ROIV1ON				BIT(1)
> +#define IMX296_FID0_ROIPH1				IMX296_REG_16BIT(0x3310)
> +#define IMX296_FID0_ROIPV1				IMX296_REG_16BIT(0x3312)
> +#define IMX296_FID0_ROIWH1				IMX296_REG_16BIT(0x3314)
> +#define IMX296_FID0_ROIWH1_MIN				80
> +#define IMX296_FID0_ROIWV1				IMX296_REG_16BIT(0x3316)
> +#define IMX296_FID0_ROIWV1_MIN				4
> +
> +#define IMX296_CM_HSST_STARTTMG				IMX296_REG_16BIT(0x4018)
> +#define IMX296_CM_HSST_ENDTMG				IMX296_REG_16BIT(0x401a)
> +#define IMX296_DA_HSST_STARTTMG				IMX296_REG_16BIT(0x404d)
> +#define IMX296_DA_HSST_ENDTMG				IMX296_REG_16BIT(0x4050)
> +#define IMX296_LM_HSST_STARTTMG				IMX296_REG_16BIT(0x4094)
> +#define IMX296_LM_HSST_ENDTMG				IMX296_REG_16BIT(0x4096)
> +#define IMX296_SST_SIEASTA1_SET				IMX296_REG_8BIT(0x40c9)
> +#define IMX296_SST_SIEASTA1PRE_1U			IMX296_REG_16BIT(0x40cc)
> +#define IMX296_SST_SIEASTA1PRE_1D			IMX296_REG_16BIT(0x40ce)
> +#define IMX296_SST_SIEASTA1PRE_2U			IMX296_REG_16BIT(0x40d0)
> +#define IMX296_SST_SIEASTA1PRE_2D			IMX296_REG_16BIT(0x40d2)
> +#define IMX296_HSST					IMX296_REG_8BIT(0x40dc)
> +#define IMX296_HSST_EN					BIT(2)
> +
> +#define IMX296_CKREQSEL					IMX296_REG_8BIT(0x4101)
> +#define IMX296_CKREQSEL_HS				BIT(2)
> +#define IMX296_GTTABLENUM				IMX296_REG_8BIT(0x4114)
> +#define IMX296_CTRL418C					IMX296_REG_8BIT(0x418c)
> +
> +struct imx296_clk_params {
> +	unsigned int freq;
> +	u8 incksel[4];
> +	u8 ctrl418c;
> +};
> +
> +static const struct imx296_clk_params imx296_clk_params[] = {
> +	{ 37125000, { 0x80, 0x0b, 0x80, 0x08 }, 116 },
> +	{ 54000000, { 0xb0, 0x0f, 0xb0, 0x0c }, 168 },
> +	{ 74250000, { 0x80, 0x0f, 0x80, 0x0c }, 232 },
> +};
> +
> +static const char * const imx296_supply_names[] = {
> +	"dvdd",
> +	"ovdd",
> +	"avdd",
> +};
> +
> +struct imx296 {
> +	struct device *dev;
> +	struct clk *clk;
> +	struct regulator_bulk_data supplies[ARRAY_SIZE(imx296_supply_names)];
> +	struct gpio_desc *reset;
> +	struct regmap *regmap;
> +
> +	const struct imx296_clk_params *clk_params;
> +	bool mono;
> +
> +	bool streaming;			/* Protected by ctrls.lock */
> +
> +	struct v4l2_subdev subdev;
> +	struct media_pad pad;
> +
> +	struct v4l2_ctrl_handler ctrls;
> +	struct v4l2_ctrl *hblank;
> +	struct v4l2_ctrl *vblank;
> +
> +	struct mutex lock;		/* Protects format and crop */
> +	struct v4l2_mbus_framefmt format;
> +	struct v4l2_rect crop;
> +};
> +
> +static inline struct imx296 *to_imx296(struct v4l2_subdev *sd)
> +{
> +	return container_of(sd, struct imx296, subdev);
> +}
> +
> +static int imx296_read(struct imx296 *sensor, u32 addr)
> +{
> +	u8 data[3] = { 0, 0, 0 };
> +	int ret;
> +
> +	ret = regmap_raw_read(sensor->regmap, addr & IMX296_REG_ADDR_MASK, data,
> +			      (addr >> IMX296_REG_SIZE_SHIFT) & 3);
> +	if (ret < 0)
> +		return ret;
> +
> +	return (data[2] << 16) | (data[1] << 8) | data[0];
> +}
> +
> +static int imx296_write(struct imx296 *sensor, u32 addr, u32 value, int *err)
> +{
> +	u8 data[3] = { value & 0xff, (value >> 8) & 0xff, value >> 16 };
> +	int ret;
> +
> +	if (err && *err)
> +		return *err;
> +
> +	ret = regmap_raw_write(sensor->regmap, addr & IMX296_REG_ADDR_MASK,
> +			       data, (addr >> IMX296_REG_SIZE_SHIFT) & 3);
> +	if (ret < 0) {
> +		dev_err(sensor->dev, "%u-bit write to 0x%04x failed: %d\n",
> +			((addr >> IMX296_REG_SIZE_SHIFT) & 3) * 8,
> +			addr & IMX296_REG_ADDR_MASK, ret);
> +		if (err)
> +			*err = ret;
> +	}
> +
> +	return ret;
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * Controls
> + */
> +
> +static const char * const imx296_test_pattern_menu[] = {
> +	"Disabled",
> +	"Multiple Pixels",
> +	"Sequence 1",
> +	"Sequence 2",
> +	"Gradient",
> +	"Row",
> +	"Column",
> +	"Cross",
> +	"Stripe",
> +	"Checks",

Interesting pattern name.

> +};
> +
> +static int imx296_s_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +	struct imx296 *sensor = container_of(ctrl->handler, struct imx296, ctrls);
> +	unsigned int vmax;
> +	int ret = 0;
> +
> +	if (!sensor->streaming)
> +		return 0;
> +
> +	switch (ctrl->id) {
> +	case V4L2_CID_EXPOSURE:
> +		/* Clamp the exposure value to VMAX. */
> +		vmax = sensor->format.height + sensor->vblank->cur.val;
> +		ctrl->val = min_t(int, ctrl->val, vmax);
> +		imx296_write(sensor, IMX296_SHS1, vmax - ctrl->val, &ret);
> +		break;
> +
> +	case V4L2_CID_ANALOGUE_GAIN:
> +		imx296_write(sensor, IMX296_GAIN, ctrl->val, &ret);
> +		break;
> +
> +	case V4L2_CID_VBLANK:
> +		imx296_write(sensor, IMX296_VMAX,
> +			     sensor->format.height + ctrl->val, &ret);
> +		break;
> +
> +	case V4L2_CID_TEST_PATTERN:
> +		if (ctrl->val) {
> +			imx296_write(sensor, IMX296_PGHPOS, 8, &ret);
> +			imx296_write(sensor, IMX296_PGVPOS, 8, &ret);
> +			imx296_write(sensor, IMX296_PGHPSTEP, 8, &ret);
> +			imx296_write(sensor, IMX296_PGVPSTEP, 8, &ret);
> +			imx296_write(sensor, IMX296_PGHPNUM, 100, &ret);
> +			imx296_write(sensor, IMX296_PGVPNUM, 100, &ret);
> +			imx296_write(sensor, IMX296_PGDATA1, 0x300, &ret);
> +			imx296_write(sensor, IMX296_PGDATA2, 0x100, &ret);
> +			imx296_write(sensor, IMX296_PGHGSTEP, 0, &ret);
> +			imx296_write(sensor, IMX296_BLKLEVEL, 0, &ret);
> +			imx296_write(sensor, IMX296_BLKLEVELAUTO,
> +				     IMX296_BLKLEVELAUTO_OFF, &ret);
> +			imx296_write(sensor, IMX296_PGCTRL,
> +				     IMX296_PGCTRL_REGEN |
> +				     IMX296_PGCTRL_CLKEN |
> +				     IMX296_PGCTRL_MODE(ctrl->val - 1), &ret);
> +		} else {
> +			imx296_write(sensor, IMX296_PGCTRL,
> +				     IMX296_PGCTRL_CLKEN, &ret);
> +			imx296_write(sensor, IMX296_BLKLEVEL, 0x3c, &ret);
> +			imx296_write(sensor, IMX296_BLKLEVELAUTO,
> +				     IMX296_BLKLEVELAUTO_ON, &ret);
> +		}
> +		break;
> +
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct v4l2_ctrl_ops imx296_ctrl_ops = {
> +	.s_ctrl = imx296_s_ctrl,
> +};
> +
> +static int imx296_ctrls_init(struct imx296 *sensor)
> +{
> +	struct v4l2_fwnode_device_properties props;
> +	unsigned int hblank;
> +	int ret;
> +
> +	ret = v4l2_fwnode_device_parse(sensor->dev, &props);
> +	if (ret < 0)
> +		return ret;
> +
> +	v4l2_ctrl_handler_init(&sensor->ctrls, 9);
> +
> +	v4l2_ctrl_new_std(&sensor->ctrls, &imx296_ctrl_ops,
> +			  V4L2_CID_EXPOSURE, 1, 1048575, 1, 1104);
> +	v4l2_ctrl_new_std(&sensor->ctrls, &imx296_ctrl_ops,
> +			  V4L2_CID_ANALOGUE_GAIN, IMX296_GAIN_MIN,
> +			  IMX296_GAIN_MAX, 1, IMX296_GAIN_MIN);
> +
> +	/*
> +	 * Horizontal blanking is controlled through the HMAX register, which
> +	 * contains a line length in INCK clock units. The INCK frequency is
> +	 * fixed to 74.25 MHz. The HMAX value is currently fixed to 1100,

It seems the driver supports other values, too. Shouldn't this be the
actual frequency?

> +	 * convert it to a number of pixels based on the nominal pixel rate.
> +	 */
> +	hblank = 1100 * 1188000000ULL / 10 / 74250000
> +	       - IMX296_PIXEL_ARRAY_WIDTH;
> +	sensor->hblank = v4l2_ctrl_new_std(&sensor->ctrls, &imx296_ctrl_ops,
> +					   V4L2_CID_HBLANK, hblank, hblank, 1,
> +					   hblank);
> +	if (sensor->hblank)
> +		sensor->hblank->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> +
> +	sensor->vblank = v4l2_ctrl_new_std(&sensor->ctrls, &imx296_ctrl_ops,
> +					   V4L2_CID_VBLANK, 30,
> +					   1048575 - IMX296_PIXEL_ARRAY_HEIGHT,
> +					   1, 30);
> +	/*
> +	 * The sensor calculates the MIPI timings internally to achieve a bit
> +	 * rate between 1122 and 1198 Mbps. The exact value is unfortunately not
> +	 * reported, at least according to the documentation. Report a nominal
> +	 * rate of 1188 Mbps as that is used by the datasheet in multiple
> +	 * examples.
> +	 */
> +	v4l2_ctrl_new_std(&sensor->ctrls, NULL, V4L2_CID_PIXEL_RATE,
> +			  1122000000 / 10, 1198000000 / 10, 1, 1188000000 / 10);

What about the link frequency?

Is this value constant for the sensor? Or should there be a list of
hardware supported link frequencies?

> +	v4l2_ctrl_new_std_menu_items(&sensor->ctrls, &imx296_ctrl_ops,
> +				     V4L2_CID_TEST_PATTERN,
> +				     ARRAY_SIZE(imx296_test_pattern_menu) - 1,
> +				     0, 0, imx296_test_pattern_menu);
> +
> +	v4l2_ctrl_new_fwnode_properties(&sensor->ctrls, &imx296_ctrl_ops,
> +					&props);
> +
> +	if (sensor->ctrls.error) {
> +		dev_err(sensor->dev, "failed to add controls (%d)\n",
> +			sensor->ctrls.error);
> +		v4l2_ctrl_handler_free(&sensor->ctrls);
> +		return sensor->ctrls.error;
> +	}
> +
> +	sensor->subdev.ctrl_handler = &sensor->ctrls;
> +
> +	return 0;
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * V4L2 Subdev Operations
> + */
> +
> +/*
> + * This table is extracted from vendor data that is entirely undocumented. The
> + * first register write is required to activate the CSI-2 output. The other
> + * entries may or may not be optional?
> + */
> +static const struct {
> +	unsigned int reg;
> +	unsigned int value;
> +} imx296_init_table[] = {
> +	{ IMX296_REG_8BIT(0x3005), 0xf0 },
> +	{ IMX296_REG_8BIT(0x309e), 0x04 },
> +	{ IMX296_REG_8BIT(0x30a0), 0x04 },
> +	{ IMX296_REG_8BIT(0x30a1), 0x3c },
> +	{ IMX296_REG_8BIT(0x30a4), 0x5f },
> +	{ IMX296_REG_8BIT(0x30a8), 0x91 },
> +	{ IMX296_REG_8BIT(0x30ac), 0x28 },
> +	{ IMX296_REG_8BIT(0x30af), 0x09 },
> +	{ IMX296_REG_8BIT(0x30df), 0x00 },
> +	{ IMX296_REG_8BIT(0x3165), 0x00 },
> +	{ IMX296_REG_8BIT(0x3169), 0x10 },
> +	{ IMX296_REG_8BIT(0x316a), 0x02 },
> +	{ IMX296_REG_8BIT(0x31c8), 0xf3 },	/* Exposure-related */
> +	{ IMX296_REG_8BIT(0x31d0), 0xf4 },	/* Exposure-related */
> +	{ IMX296_REG_8BIT(0x321a), 0x00 },
> +	{ IMX296_REG_8BIT(0x3226), 0x02 },
> +	{ IMX296_REG_8BIT(0x3256), 0x01 },
> +	{ IMX296_REG_8BIT(0x3541), 0x72 },
> +	{ IMX296_REG_8BIT(0x3516), 0x77 },
> +	{ IMX296_REG_8BIT(0x350b), 0x7f },
> +	{ IMX296_REG_8BIT(0x3758), 0xa3 },
> +	{ IMX296_REG_8BIT(0x3759), 0x00 },
> +	{ IMX296_REG_8BIT(0x375a), 0x85 },
> +	{ IMX296_REG_8BIT(0x375b), 0x00 },
> +	{ IMX296_REG_8BIT(0x3832), 0xf5 },
> +	{ IMX296_REG_8BIT(0x3833), 0x00 },
> +	{ IMX296_REG_8BIT(0x38a2), 0xf6 },
> +	{ IMX296_REG_8BIT(0x38a3), 0x00 },
> +	{ IMX296_REG_8BIT(0x3a00), 0x80 },
> +	{ IMX296_REG_8BIT(0x3d48), 0xa3 },
> +	{ IMX296_REG_8BIT(0x3d49), 0x00 },
> +	{ IMX296_REG_8BIT(0x3d4a), 0x85 },
> +	{ IMX296_REG_8BIT(0x3d4b), 0x00 },
> +	{ IMX296_REG_8BIT(0x400e), 0x58 },
> +	{ IMX296_REG_8BIT(0x4014), 0x1c },
> +	{ IMX296_REG_8BIT(0x4041), 0x2a },
> +	{ IMX296_REG_8BIT(0x40a2), 0x06 },
> +	{ IMX296_REG_8BIT(0x40c1), 0xf6 },
> +	{ IMX296_REG_8BIT(0x40c7), 0x0f },
> +	{ IMX296_REG_8BIT(0x40c8), 0x00 },
> +	{ IMX296_REG_8BIT(0x4174), 0x00 },
> +};
> +
> +static int imx296_setup(struct imx296 *sensor)
> +{
> +	const struct v4l2_mbus_framefmt *format = &sensor->format;
> +	const struct v4l2_rect *crop = &sensor->crop;
> +	unsigned int i;
> +	int ret = 0;
> +
> +	for (i = 0; i < ARRAY_SIZE(imx296_init_table); ++i)
> +		imx296_write(sensor, imx296_init_table[i].reg,
> +			     imx296_init_table[i].value, &ret);
> +
> +	if (crop->width != IMX296_PIXEL_ARRAY_WIDTH ||
> +	    crop->height != IMX296_PIXEL_ARRAY_HEIGHT) {
> +		imx296_write(sensor, IMX296_FID0_ROI,
> +			     IMX296_FID0_ROIH1ON | IMX296_FID0_ROIV1ON, &ret);
> +		imx296_write(sensor, IMX296_FID0_ROIPH1, crop->left, &ret);
> +		imx296_write(sensor, IMX296_FID0_ROIPV1, crop->top, &ret);
> +		imx296_write(sensor, IMX296_FID0_ROIWH1, crop->width, &ret);
> +		imx296_write(sensor, IMX296_FID0_ROIWV1, crop->height, &ret);
> +	} else {
> +		imx296_write(sensor, IMX296_FID0_ROI, 0, &ret);
> +	}
> +
> +	imx296_write(sensor, IMX296_CTRL0D,
> +		     (crop->width != format->width ?
> +		      IMX296_CTRL0D_HADD_ON_BINNING : 0) |
> +		     (crop->height != format->height ?
> +		      IMX296_CTRL0D_WINMODE_FD_BINNING : 0),
> +		     &ret);
> +
> +	/*
> +	 * HMAX and VMAX configure horizontal and vertical blanking by
> +	 * specifying the total line time and frame time respectively. The line
> +	 * time is specified in operational clock units (which appears to be the
> +	 * output of an internal PLL, fixed at 74.25 MHz regardless of the
> +	 * exernal clock frequency), while the frame time is specified as a
> +	 * number of lines.
> +	 *
> +	 * In the vertical direction the sensor outputs the following:
> +	 *
> +	 * - one line for the FS packet
> +	 * - two lines of embedded data (DT 0x12)
> +	 * - six null lines (DT 0x10)
> +	 * - four lines of vertical effective optical black (DT 0x37)
> +	 * - 8 to 1088 lines of active image data (RAW10, DT 0x2b)
> +	 * - one line for the FE packet
> +	 * - 16 or more lines of vertical blanking
> +	 */
> +	imx296_write(sensor, IMX296_HMAX, 1100, &ret);
> +	imx296_write(sensor, IMX296_VMAX,
> +		     format->height + sensor->vblank->cur.val, &ret);
> +
> +	for (i = 0; i < ARRAY_SIZE(sensor->clk_params->incksel); ++i)
> +		imx296_write(sensor, IMX296_INCKSEL(i),
> +			     sensor->clk_params->incksel[i], &ret);
> +	imx296_write(sensor, IMX296_GTTABLENUM, 0xc5, &ret);
> +	imx296_write(sensor, IMX296_CTRL418C, sensor->clk_params->ctrl418c,
> +		     &ret);
> +
> +	imx296_write(sensor, IMX296_GAINDLY, IMX296_GAINDLY_NONE, &ret);
> +	imx296_write(sensor, IMX296_BLKLEVEL, 0x03c, &ret);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	return __v4l2_ctrl_handler_setup(&sensor->ctrls);
> +}
> +
> +static int imx296_stream_on(struct imx296 *sensor)
> +{
> +	int ret = 0;
> +
> +	imx296_write(sensor, IMX296_CTRL00, 0, &ret);
> +	usleep_range(2000, 5000);
> +	imx296_write(sensor, IMX296_CTRL0A, 0, &ret);
> +
> +	return ret;
> +}
> +
> +static int imx296_stream_off(struct imx296 *sensor)
> +{
> +	int ret = 0;
> +
> +	imx296_write(sensor, IMX296_CTRL0A, IMX296_CTRL0A_XMSTA, &ret);
> +	imx296_write(sensor, IMX296_CTRL00, IMX296_CTRL00_STANDBY, &ret);
> +
> +	return ret;
> +}
> +
> +static int imx296_s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	struct imx296 *sensor = to_imx296(sd);
> +	int ret;
> +
> +	if (!enable) {
> +		ret = imx296_stream_off(sensor);
> +
> +		pm_runtime_mark_last_busy(sensor->dev);
> +		pm_runtime_put_autosuspend(sensor->dev);
> +
> +		mutex_lock(sensor->ctrls.lock);
> +		sensor->streaming = false;
> +		mutex_unlock(sensor->ctrls.lock);
> +
> +		return ret;
> +	}
> +
> +	mutex_lock(sensor->ctrls.lock);
> +
> +	ret = pm_runtime_get_sync(sensor->dev);
> +	if (ret < 0)
> +		goto done;
> +
> +	ret = imx296_setup(sensor);
> +	if (ret < 0)
> +		goto done;
> +
> +	/*
> +	 * Set streaming to true to ensure __v4l2_ctrl_handler_setup() will set
> +	 * the controls. The flag is reset to false further down if an error
> +	 * occurs.
> +	 */
> +	sensor->streaming = true;
> +
> +	ret = __v4l2_ctrl_handler_setup(&sensor->ctrls);
> +	if (ret < 0)
> +		goto done;
> +
> +	ret = imx296_stream_on(sensor);
> +
> +done:
> +	if (ret < 0) {
> +		/*
> +		 * In case of error, turn the power off synchronously as the
> +		 * device likely has no other chance to recover.
> +		 */
> +		pm_runtime_put_sync(sensor->dev);
> +		sensor->streaming = false;
> +	}
> +
> +	mutex_unlock(sensor->ctrls.lock);
> +
> +	return ret;
> +}
> +
> +static int imx296_enum_mbus_code(struct v4l2_subdev *sd,
> +				 struct v4l2_subdev_state *state,
> +				 struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	struct imx296 *sensor = to_imx296(sd);
> +
> +	if (code->index != 0)
> +		return -EINVAL;
> +
> +	code->code = sensor->mono ? MEDIA_BUS_FMT_Y10_1X10
> +		   : MEDIA_BUS_FMT_SBGGR10_1X10;
> +
> +	return 0;
> +}
> +
> +static int imx296_enum_frame_size(struct v4l2_subdev *sd,
> +				  struct v4l2_subdev_state *state,
> +				  struct v4l2_subdev_frame_size_enum *fse)
> +{
> +	struct imx296 *sensor = to_imx296(sd);
> +
> +	if (fse->index >= 2 || fse->code != sensor->format.code)
> +		return -EINVAL;
> +
> +	fse->min_width = IMX296_PIXEL_ARRAY_WIDTH / (fse->index + 1);
> +	fse->max_width = fse->min_width;
> +	fse->min_height = IMX296_PIXEL_ARRAY_HEIGHT / (fse->index + 1);
> +	fse->max_height = fse->min_height;
> +
> +	return 0;
> +}
> +
> +static struct v4l2_mbus_framefmt *
> +imx296_get_pad_format(struct imx296 *sensor, struct v4l2_subdev_state *state,
> +		      unsigned int pad, u32 which)
> +{
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_format(&sensor->subdev, state, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &sensor->format;
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static struct v4l2_rect *
> +imx296_get_pad_crop(struct imx296 *sensor, struct v4l2_subdev_state *state,
> +		    unsigned int pad, u32 which)
> +{
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_crop(&sensor->subdev, state, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &sensor->crop;
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static int imx296_get_format(struct v4l2_subdev *sd,
> +			     struct v4l2_subdev_state *state,
> +			     struct v4l2_subdev_format *fmt)
> +{
> +	struct imx296 *sensor = to_imx296(sd);
> +
> +	mutex_lock(&sensor->lock);
> +	fmt->format = *imx296_get_pad_format(sensor, state, fmt->pad,
> +					     fmt->which);
> +	mutex_unlock(&sensor->lock);
> +
> +	return 0;
> +}
> +
> +static int imx296_set_format(struct v4l2_subdev *sd,
> +			     struct v4l2_subdev_state *state,
> +			     struct v4l2_subdev_format *fmt)
> +{
> +	struct imx296 *sensor = to_imx296(sd);
> +	struct v4l2_mbus_framefmt *format;
> +	struct v4l2_rect *crop;
> +
> +	crop = imx296_get_pad_crop(sensor, state, fmt->pad, fmt->which);
> +	format = imx296_get_pad_format(sensor, state, fmt->pad, fmt->which);
> +
> +	mutex_lock(&sensor->lock);
> +
> +	/*
> +	 * Binning is only allowed when cropping is disabled according to the
> +	 * documentation. This should be double-checked.
> +	 */
> +	if (crop->width == IMX296_PIXEL_ARRAY_WIDTH &&
> +	    crop->height == IMX296_PIXEL_ARRAY_HEIGHT) {
> +		unsigned int width;
> +		unsigned int height;
> +		unsigned int hratio;
> +		unsigned int vratio;
> +
> +		/* Clamp the width and height to avoid dividing by zero. */
> +		width = clamp_t(unsigned int, fmt->format.width,
> +				crop->width / 2, crop->width);
> +		height = clamp_t(unsigned int, fmt->format.height,
> +				 crop->height / 2, crop->height);
> +
> +		hratio = DIV_ROUND_CLOSEST(crop->width, width);
> +		vratio = DIV_ROUND_CLOSEST(crop->height, height);
> +
> +		format->width = crop->width / hratio;
> +		format->height = crop->height / vratio;
> +	} else {
> +		format->width = crop->width;
> +		format->height = crop->height;
> +	}
> +
> +	format->code = sensor->mono ? MEDIA_BUS_FMT_Y10_1X10
> +		     : MEDIA_BUS_FMT_SBGGR10_1X10;
> +	format->field = V4L2_FIELD_NONE;
> +	format->colorspace = V4L2_COLORSPACE_RAW;
> +	format->ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> +	format->quantization = V4L2_QUANTIZATION_FULL_RANGE;
> +	format->xfer_func = V4L2_XFER_FUNC_NONE;
> +
> +	fmt->format = *format;
> +
> +	mutex_unlock(&sensor->lock);
> +
> +	return 0;
> +}
> +
> +static int imx296_get_selection(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_state *state,
> +				struct v4l2_subdev_selection *sel)
> +{
> +	struct imx296 *sensor = to_imx296(sd);
> +
> +	switch (sel->target) {
> +	case V4L2_SEL_TGT_CROP:
> +		mutex_lock(&sensor->lock);
> +		sel->r = *imx296_get_pad_crop(sensor, state, sel->pad,
> +					      sel->which);
> +		mutex_unlock(&sensor->lock);
> +		break;
> +
> +	case V4L2_SEL_TGT_CROP_DEFAULT:
> +	case V4L2_SEL_TGT_CROP_BOUNDS:
> +	case V4L2_SEL_TGT_NATIVE_SIZE:
> +		sel->r.left = 0;
> +		sel->r.top = 0;
> +		sel->r.width = IMX296_PIXEL_ARRAY_WIDTH;
> +		sel->r.height = IMX296_PIXEL_ARRAY_HEIGHT;
> +		break;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int imx296_set_selection(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_state *state,
> +				struct v4l2_subdev_selection *sel)
> +{
> +	struct imx296 *sensor = to_imx296(sd);
> +	struct v4l2_mbus_framefmt *format;
> +	struct v4l2_rect *crop;
> +	struct v4l2_rect rect;
> +
> +	if (sel->target != V4L2_SEL_TGT_CROP)
> +		return -EINVAL;
> +
> +	/*
> +	 * Clamp the crop rectangle boundaries and align them to a multiple of 4
> +	 * pixels to satisfy hardware requirements.
> +	 */
> +	rect.left = clamp(ALIGN(sel->r.left, 4), 0,
> +			  IMX296_PIXEL_ARRAY_WIDTH - IMX296_FID0_ROIWH1_MIN);
> +	rect.top = clamp(ALIGN(sel->r.top, 4), 0,
> +			  IMX296_PIXEL_ARRAY_HEIGHT - IMX296_FID0_ROIWV1_MIN);
> +	rect.width = clamp_t(unsigned int, ALIGN(sel->r.width, 4),
> +			     IMX296_FID0_ROIWH1_MIN, IMX296_PIXEL_ARRAY_WIDTH);
> +	rect.height = clamp_t(unsigned int, ALIGN(sel->r.height, 4),
> +			      IMX296_FID0_ROIWV1_MIN, IMX296_PIXEL_ARRAY_HEIGHT);
> +
> +	rect.width = min_t(unsigned int, rect.width,
> +			   IMX296_PIXEL_ARRAY_WIDTH - rect.left);
> +	rect.height = min_t(unsigned int, rect.height,
> +			    IMX296_PIXEL_ARRAY_HEIGHT - rect.top);
> +
> +	crop = imx296_get_pad_crop(sensor, state, sel->pad, sel->which);
> +
> +	mutex_lock(&sensor->lock);
> +
> +	if (rect.width != crop->width || rect.height != crop->height) {
> +		/*
> +		 * Reset the output image size if the crop rectangle size has
> +		 * been modified.
> +		 */
> +		format = imx296_get_pad_format(sensor, state, sel->pad,
> +					       sel->which);
> +		format->width = rect.width;
> +		format->height = rect.height;
> +	}
> +
> +	*crop = rect;
> +	sel->r = rect;
> +
> +	mutex_unlock(&sensor->lock);
> +
> +	return 0;
> +}
> +
> +static int imx296_init_cfg(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_state *state)
> +{
> +	struct v4l2_subdev_selection sel = {
> +		.target = V4L2_SEL_TGT_CROP,
> +		.which = state ? V4L2_SUBDEV_FORMAT_TRY
> +		       : V4L2_SUBDEV_FORMAT_ACTIVE,
> +		.r.width = IMX296_PIXEL_ARRAY_WIDTH,
> +		.r.height = IMX296_PIXEL_ARRAY_HEIGHT,
> +	};
> +	struct v4l2_subdev_format format = {
> +		.which = state ? V4L2_SUBDEV_FORMAT_TRY
> +		       : V4L2_SUBDEV_FORMAT_ACTIVE,
> +		.format = {
> +			.width = IMX296_PIXEL_ARRAY_WIDTH,
> +			.height = IMX296_PIXEL_ARRAY_HEIGHT,
> +		},
> +	};
> +
> +	imx296_set_selection(sd, state, &sel);
> +	imx296_set_format(sd, state, &format);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_video_ops imx296_subdev_video_ops = {
> +	.s_stream = imx296_s_stream,
> +};
> +
> +static const struct v4l2_subdev_pad_ops imx296_subdev_pad_ops = {
> +	.enum_mbus_code = imx296_enum_mbus_code,
> +	.enum_frame_size = imx296_enum_frame_size,
> +	.get_fmt = imx296_get_format,
> +	.set_fmt = imx296_set_format,
> +	.get_selection = imx296_get_selection,
> +	.set_selection = imx296_set_selection,
> +	.init_cfg = imx296_init_cfg,
> +};
> +
> +static const struct v4l2_subdev_ops imx296_subdev_ops = {
> +	.video = &imx296_subdev_video_ops,
> +	.pad = &imx296_subdev_pad_ops,
> +};
> +
> +/* -----------------------------------------------------------------------------
> + * Power management
> + */
> +
> +static int imx296_power_on(struct imx296 *sensor)
> +{
> +	int ret;
> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(sensor->supplies),
> +				    sensor->supplies);
> +	if (ret < 0)
> +		return ret;
> +
> +	udelay(1);

This is a very small delay.

> +
> +	ret = gpiod_direction_output(sensor->reset, 0);
> +	if (ret < 0)
> +		goto err_supply;
> +
> +	udelay(1);


This one as well.

> +
> +	ret = clk_prepare_enable(sensor->clk);
> +	if (ret < 0)
> +		goto err_reset;
> +
> +	/*
> +	 * The documentation doesn't explicitly say how much time is required
> +	 * after providing a clock and before starting I2C communication. It
> +	 * mentions a delay of 20µs in 4-wire mode, but tests showed that a
> +	 * delay of 100µs resulted in I2C communication failures, while 500µs
> +	 * seems to be enough. Be conservative.
> +	 */
> +	usleep_range(1000, 2000);
> +
> +	return 0;
> +
> +err_reset:
> +	gpiod_direction_output(sensor->reset, 1);
> +err_supply:
> +	regulator_bulk_disable(ARRAY_SIZE(sensor->supplies), sensor->supplies);
> +	return ret;
> +}
> +
> +static void imx296_power_off(struct imx296 *sensor)
> +{
> +	clk_disable_unprepare(sensor->clk);
> +	gpiod_direction_output(sensor->reset, 1);
> +	regulator_bulk_disable(ARRAY_SIZE(sensor->supplies), sensor->supplies);
> +}
> +
> +static int __maybe_unused imx296_runtime_resume(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
> +	struct imx296 *sensor = to_imx296(subdev);
> +
> +	return imx296_power_on(sensor);
> +}
> +
> +static int __maybe_unused imx296_runtime_suspend(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
> +	struct imx296 *sensor = to_imx296(subdev);
> +
> +	imx296_power_off(sensor);
> +
> +	return 0;

I'd merge these two with imx296_power_o{n,ff}.

> +}
> +
> +static const struct dev_pm_ops imx296_pm_ops = {
> +	SET_RUNTIME_PM_OPS(imx296_runtime_suspend, imx296_runtime_resume, NULL)
> +};
> +
> +/* -----------------------------------------------------------------------------
> + * Probe & Remove
> + */
> +
> +static int imx296_read_temperature(struct imx296 *sensor, int *temp)
> +{
> +	int tmdout;
> +	int ret;
> +
> +	ret = imx296_write(sensor, IMX296_TMDCTRL, IMX296_TMDCTRL_LATCH, NULL);
> +	if (ret < 0)
> +		return ret;
> +
> +	tmdout = imx296_read(sensor, IMX296_TMDOUT) & IMX296_TMDOUT_MASK;
> +	if (tmdout < 0)
> +		return tmdout;
> +
> +	/* T(°C) = 246.312 - 0.304 * TMDOUT */;
> +	*temp = 246312 - 304 * tmdout;
> +
> +	return imx296_write(sensor, IMX296_TMDCTRL, 0, NULL);
> +}
> +
> +static int imx296_identify_model(struct imx296 *sensor)
> +{
> +	unsigned int model;
> +	int temp = 0;
> +	int ret;
> +
> +	/*
> +	 * While most registers can be read when the sensor is in standby, this
> +	 * is not the case of the sensor info register :-(
> +	 */
> +	ret = imx296_write(sensor, IMX296_CTRL00, 0, NULL);
> +	if (ret < 0) {
> +		dev_err(sensor->dev,
> +			"failed to get sensor out of standby (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	ret = imx296_read(sensor, IMX296_SENSOR_INFO);
> +	if (ret < 0) {
> +		dev_err(sensor->dev, "failed to read sensor information (%d)\n",
> +			ret);
> +		goto done;
> +	}
> +
> +	model = (ret >> 6) & 0x1ff;
> +
> +	switch (model) {
> +	case 296:
> +		sensor->mono = ret & IMX296_SENSOR_INFO_MONO;
> +		break;
> +	/*
> +	 * The IMX297 seems to share features with the IMX296, it may be
> +	 * possible to support it in the same driver.
> +	 */
> +	case 297:
> +	default:
> +		dev_err(sensor->dev, "invalid device model 0x%04x\n", ret);
> +		ret = -ENODEV;
> +		goto done;
> +	}
> +
> +	ret = imx296_read_temperature(sensor, &temp);
> +	if (ret < 0)
> +		goto done;
> +
> +	dev_info(sensor->dev, "found IMX%u%s (%u.%uC)\n", model,
> +		 sensor->mono ? "LL" : "LQ", temp / 1000, (temp / 100) % 10);
> +
> +done:
> +	imx296_write(sensor, IMX296_CTRL00, IMX296_CTRL00_STANDBY, NULL);
> +	return ret;
> +}
> +
> +static const struct regmap_config imx296_regmap_config = {
> +	.reg_bits = 16,
> +	.val_bits = 8,
> +
> +	.wr_table = &(const struct regmap_access_table) {
> +		.no_ranges = (const struct regmap_range[]) {
> +			{
> +				.range_min = IMX296_SENSOR_INFO & 0xffff,
> +				.range_max = (IMX296_SENSOR_INFO & 0xffff) + 1,
> +			},
> +		},
> +		.n_no_ranges = 1,
> +	},
> +};
> +
> +static int imx296_probe(struct i2c_client *client)
> +{
> +	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
> +	unsigned long clk_rate;
> +	struct imx296 *sensor;
> +	unsigned int i;
> +	int ret;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
> +		dev_warn(&adapter->dev,
> +			 "I2C-Adapter doesn't support I2C_FUNC_SMBUS_BYTE\n");
> +		return -EIO;
> +	}
> +
> +	sensor = devm_kzalloc(&client->dev, sizeof(*sensor), GFP_KERNEL);
> +	if (!sensor)
> +		return -ENOMEM;
> +
> +	sensor->dev = &client->dev;
> +
> +	mutex_init(&sensor->lock);

You could simplify error handling a little by moving mutex init later. Up
to you.

> +
> +	/* Acquire resources. */
> +	for (i = 0; i < ARRAY_SIZE(sensor->supplies); ++i)
> +		sensor->supplies[i].supply = imx296_supply_names[i];
> +
> +	ret = devm_regulator_bulk_get(sensor->dev, ARRAY_SIZE(sensor->supplies),
> +				      sensor->supplies);
> +	if (ret) {
> +		dev_err_probe(sensor->dev, ret, "failed to get supplies\n");
> +		goto err_mutex;
> +	}
> +
> +	sensor->reset = devm_gpiod_get_optional(sensor->dev, "reset",
> +						GPIOD_OUT_HIGH);
> +	if (IS_ERR(sensor->reset)) {
> +		ret = PTR_ERR(sensor->reset);
> +		dev_err_probe(sensor->dev, ret, "failed to get reset GPIO\n");
> +		goto err_mutex;
> +	}
> +
> +	sensor->clk = devm_clk_get(sensor->dev, "inck");
> +	if (IS_ERR(sensor->clk)) {
> +		ret = PTR_ERR(sensor->clk);
> +		dev_err_probe(sensor->dev, ret, "failed to get clock\n");
> +		goto err_mutex;
> +	}
> +
> +	clk_rate = clk_get_rate(sensor->clk);
> +	for (i = 0; i < ARRAY_SIZE(imx296_clk_params); ++i) {
> +		if (clk_rate == imx296_clk_params[i].freq) {
> +			sensor->clk_params = &imx296_clk_params[i];
> +			break;
> +		}
> +	}
> +
> +	if (!sensor->clk_params) {
> +		dev_err(sensor->dev, "unsupported clock rate %lu\n", clk_rate);
> +		ret = -EINVAL;
> +		goto err_mutex;
> +	}
> +
> +	sensor->regmap = devm_regmap_init_i2c(client, &imx296_regmap_config);
> +	if (IS_ERR(sensor->regmap)) {
> +		ret = PTR_ERR(sensor->regmap);
> +		goto err_mutex;
> +	}
> +
> +	/*
> +	 * Enable power management. The driver supports runtime PM, but needs to
> +	 * work when runtime PM is disabled in the kernel. To that end, power
> +	 * the sensor on manually here, identify it, and fully initialize it.
> +	 */
> +	ret = imx296_power_on(sensor);
> +	if (ret < 0)
> +		goto err_mutex;
> +
> +	ret = imx296_identify_model(sensor);
> +	if (ret < 0)
> +		goto err_power;
> +
> +	/* Initialize the V4L2 subdev, controls and media entity. */
> +	v4l2_i2c_subdev_init(&sensor->subdev, client, &imx296_subdev_ops);
> +
> +	ret = imx296_ctrls_init(sensor);
> +	if (ret < 0)
> +		goto err_power;
> +
> +	sensor->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +	sensor->pad.flags = MEDIA_PAD_FL_SOURCE;
> +	sensor->subdev.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> +	ret = media_entity_pads_init(&sensor->subdev.entity, 1, &sensor->pad);
> +	if (ret < 0)
> +		goto err_ctrls;
> +
> +	imx296_init_cfg(&sensor->subdev, NULL);
> +
> +	/*
> +	 * Enable runtime PM. As the device has been powered manually, mark it
> +	 * as active, and increase the usage count without resuming the device.
> +	 */
> +	pm_runtime_set_active(sensor->dev);
> +	pm_runtime_get_noresume(sensor->dev);
> +	pm_runtime_enable(sensor->dev);
> +
> +	ret = v4l2_async_register_subdev(&sensor->subdev);
> +	if (ret < 0)
> +		goto err_pm;
> +
> +	/*
> +	 * Finally, enable autosuspend and decrease the usage count. The device
> +	 * will get suspended after the autosuspend delay, turning the power
> +	 * off.
> +	 */
> +	pm_runtime_set_autosuspend_delay(sensor->dev, 1000);
> +	pm_runtime_use_autosuspend(sensor->dev);
> +	pm_runtime_put_autosuspend(sensor->dev);
> +
> +	return 0;
> +
> +err_pm:
> +	pm_runtime_disable(sensor->dev);
> +	pm_runtime_put_noidle(sensor->dev);
> +	media_entity_cleanup(&sensor->subdev.entity);
> +err_ctrls:
> +	v4l2_ctrl_handler_free(&sensor->ctrls);
> +err_power:
> +	imx296_power_off(sensor);
> +err_mutex:
> +	mutex_destroy(&sensor->lock);
> +	return ret;
> +}
> +
> +static int imx296_remove(struct i2c_client *client)
> +{
> +	struct v4l2_subdev *subdev = i2c_get_clientdata(client);
> +	struct imx296 *sensor = to_imx296(subdev);
> +
> +	v4l2_async_unregister_subdev(subdev);
> +	media_entity_cleanup(&subdev->entity);
> +	v4l2_ctrl_handler_free(&sensor->ctrls);
> +
> +	/*
> +	 * Disable runtime PM. In case runtime PM is disabled in the kernel,
> +	 * make sure to turn power off manually.
> +	 */
> +	pm_runtime_disable(sensor->dev);
> +	if (!pm_runtime_status_suspended(sensor->dev))
> +		imx296_power_off(sensor);
> +	pm_runtime_set_suspended(sensor->dev);
> +
> +	mutex_destroy(&sensor->lock);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id imx296_of_match[] = {
> +	{ .compatible = "sony,imx296" },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, imx296_of_match);
> +
> +static struct i2c_driver imx296_i2c_driver = {
> +	.driver = {
> +		.of_match_table = imx296_of_match,
> +		.name = "imx296",
> +		.pm = &imx296_pm_ops
> +	},
> +	.probe_new = imx296_probe,
> +	.remove = imx296_remove,
> +};
> +
> +module_i2c_driver(imx296_i2c_driver);
> +
> +MODULE_DESCRIPTION("Sony IMX296 Camera driver");
> +MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
> +MODULE_LICENSE("GPL v2");

-- 
Kind regards,

Sakari Ailus