Re: [PATCH 2/2] media: i2c: Add Sony IMX908 image sensor driver

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Lachlan,

Thank you for the patch.

On Thu, Jul 30, 2026 at 11:15:25AM +0900, Lachlan Michael wrote:
> Add a V4L2 sub-device driver for the Sony IMX908 CMOS image sensor.
> 
> The driver supports:
> - RAW10 and RAW12 output formats
> - Exposure and analogue gain controls
> - Horizontal and vertical image flipping
> - HBLANK and VBLANK controls
> - Full-resolution and window-cropping modes
> - Test pattern generation
>  
> HDR modes and RAW16 output are not currently supported.
> 
> The driver has been tested with libcamera on Raspberry Pi 5 based
> hardware.
> 
> Signed-off-by: Lachlan Michael <lachlan.michael@sony.com>
> ---
>  drivers/media/i2c/Kconfig  |   11 +
>  drivers/media/i2c/Makefile |    1 +
>  drivers/media/i2c/imx908.c | 1593 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 1605 insertions(+)
>  create mode 100644 drivers/media/i2c/imx908.c
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 5d173e0ecf42..8e521f21414b 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -287,6 +287,17 @@ config VIDEO_IMX415
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called imx415.
>  
> +config VIDEO_IMX908
> +	tristate "Sony IMX908 sensor support"
> +	depends on GPIOLIB
> +	select V4L2_CCI_I2C
> +	help
> +	  This is a Video4Linux2 sensor driver for the Sony
> +	  IMX908 CMOS image sensor.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will called imx908.
> +
>  config VIDEO_MAX9271_LIB
>  	tristate
>  
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index e45359efe0e4..3ccf6d29bbfd 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -61,6 +61,7 @@ obj-$(CONFIG_VIDEO_IMX335) += imx335.o
>  obj-$(CONFIG_VIDEO_IMX355) += imx355.o
>  obj-$(CONFIG_VIDEO_IMX412) += imx412.o
>  obj-$(CONFIG_VIDEO_IMX415) += imx415.o
> +obj-$(CONFIG_VIDEO_IMX908) += imx908.o
>  obj-$(CONFIG_VIDEO_IR_I2C) += ir-kbd-i2c.o
>  obj-$(CONFIG_VIDEO_ISL7998X) += isl7998x.o
>  obj-$(CONFIG_VIDEO_KS0127) += ks0127.o
> diff --git a/drivers/media/i2c/imx908.c b/drivers/media/i2c/imx908.c
> new file mode 100644
> index 000000000000..6ec1322f9c16
> --- /dev/null
> +++ b/drivers/media/i2c/imx908.c
> @@ -0,0 +1,1593 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * V4L2 driver for Sony IMX908
> + *
> + * Diagonal 6.42 mm (Type 1/2.8) CMOS image sensor with 8.39 M pixels.
> + *
> + * Copyright 2026 Sony Semiconductor Solutions Corporation
> + *
> + */
> +
> +#include <linux/align.h>
> +#include <linux/array_size.h>
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/math64.h>
> +#include <linux/minmax.h>
> +#include <linux/module.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/property.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <media/media-entity.h>
> +#include <media/v4l2-cci.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-event.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-mediabus.h>
> +#include <media/v4l2-rect.h>
> +#include <media/v4l2-subdev.h>
> +
> +/* ---- IMX908 Registers --------- */
> +#define IMX908_REG_STANDBY	CCI_REG8(0x3000)
> +#define IMX908_STANDBY_EN	BIT(0)		/* Standby mode */
> +#define IMX908_STANDBY_CANCEL	0x00		/* Operating mode */
> +#define IMX908_REG_XMSTA	CCI_REG8(0x3002)	/* [0] Init 1h */
> +#define IMX908_START_CONTROLLER	0x00	/* Controller mode operation start */
> +#define IMX908_STOP_CONTROLLER	0x01	/* Controller mode operation stop */
> +#define IMX908_REG_XMASTER	CCI_REG8(0x3003)	/* [0] Init 0h */
> +#define IMX908_CONTROLLER_MODE	0x00
> +#define IMX908_REG_INCK_SEL	CCI_REG8(0x3014)	/* 0:74.25 1:37.125 2:72 3:27 4:24 */
> +#define IMX908_REG_DATARATE_SEL	CCI_REG8(0x3015)
> +
> +/* ---- Crop */
> +#define IMX908_REG_WINMODE	CCI_REG8(0x3018)	/* [3:0] */
> +#define IMX908_WINMODE_ALLPIX	0x00	/* All-pixel readout mode */
> +#define IMX908_WINMODE_CROP	0x04	/* Window cropping mode */
> +
> +/* ---- Flip */
> +#define IMX908_REG_HREVERSE	CCI_REG8(0x3020)	/* 0:Normal, 1:Inverted */
> +#define IMX908_REG_VREVERSE	CCI_REG8(0x3021)	/* 0:Normal, 1:Inverted */
> +
> +/* ---- Internal Analog to Digital conversion bit width */
> +#define IMX908_REG_ADBIT	CCI_REG8(0x3022)
> +#define IMX908_ADBIT_10BIT	0x00	/* 10-bit */
> +#define IMX908_ADBIT_12BIT	0x01	/* 11-bit + digital dither */
> +
> +#define IMX908_REG_MDBIT	CCI_REG8(0x3023)
> +#define IMX908_MDBIT_RAW10	0x00
> +#define IMX908_MDBIT_RAW12	0x01
> +
> +/* ---- VMAX  Frame length in lines */
> +#define IMX908_REG_VMAX		CCI_REG24_LE(0x3028)	/* [19:0] */
> +#define IMX908_VMAX_MAX		0xfffff
> +#define IMX908_VMAX_DEFAULT	2250U
> +/*
> + * Window cropping mode restrictions:
> + * VMAX >= PIX_VWIDTH + 70
> + * VMAX >= 1206
> + */
> +#define IMX908_VMAX_CROP_MIN_MARGIN	70
> +#define IMX908_VMAX_CROP_MIN_LIMIT	1206
> +
> +/* ---- HMAX Line length in clocks */
> +#define IMX908_REG_HMAX		CCI_REG16_LE(0x302c)	/* [15:0] */
> +#define IMX908_HMAX_MAX		0xffff
> +#define IMX908_HMAX_DEFAULT	1100U
> +
> +/* ---- Cropping related */
> +#define IMX908_REG_PIX_HST	CCI_REG16_LE(0x303c)	/* [12:0] Init 0h */
> +#define IMX908_REG_PIX_HWIDTH	CCI_REG16_LE(0x303e)	/* [12:0] Init 0F10h */
> +#define IMX908_REG_LANEMODE	CCI_REG8(0x3040)	/* 1:2-lane, 3:4-lane */
> +#define IMX908_REG_PIX_VST	CCI_REG16_LE(0x3044)	/* [12:0] Init 0h */
> +#define IMX908_REG_PIX_VWIDTH	CCI_REG16_LE(0x3046)	/* [12:0] Init 0884h */
> +#define IMX908_CROP_ALIGN_VSTART	4U
> +#define IMX908_CROP_ALIGN_VWIDTH	4U
> +#define IMX908_CROP_ALIGN_HSTART	4U
> +#define IMX908_CROP_ALIGN_HWIDTH	16U
> +#define IMX908_CROP_MIN_HEIGHT		1136U
> +#define IMX908_CROP_MIN_WIDTH		1040U
> +
> +/* ---- Shutter */
> +#define IMX908_REG_SHR0		CCI_REG24_LE(0x3050)	/* [19:0] */
> +#define IMX908_MIN_SHR0		7U
> +
> +/*
> + * Analogue gain control
> + * Range is from 0 to 100 (0dB - 30dB) with 0.3dB step size
> + * Values from 101 to 240 are valid but correspond to additional digital gain
> + * (0.3dB - 42dB) so don't expose it to userspace
> + */
> +#define IMX908_REG_GAIN		CCI_REG16_LE(0x3070)	/* [10:0] */
> +#define IMX908_ANA_GAIN_MAX	100
> +#define IMX908_ANA_GAIN_MIN	0
> +#define IMX908_ANA_GAIN_STEP	1
> +#define IMX908_ANA_GAIN_DEFAULT	0
> +
> +/* ---- XVS/XHS output mode */
> +#define IMX908_XXS_DRV		CCI_REG8(0x30a6)	/* [1:0] XVS_DRV [3:2] XHS_DRV */
> +
> +#define IMX908_REG_BLKLEVEL	CCI_REG16_LE(0x30dc)	/* [15:0] black level */
> +
> +/* ---- Test Pattern Generator (TPG) registers */
> +#define IMX908_REG_TPG_EN	CCI_REG8(0x30e0)
> +#define IMX908_TPG_EN_BIT	BIT(0)
> +#define IMX908_REG_TPG_PATSEL	CCI_REG8(0x30e2)	/* [4:0] pattern idx */
> +#define IMX908_REG_TESTCLKEN	CCI_REG8(0x4900)
> +#define IMX908_TESTCLKEN_BIT	BIT(3)
> +
> +#define IMX908_REG_TYPE_ID	CCI_REG16_LE(0x4c0c)
> +#define IMX908_CHIP_ID		0x038c			/* 908 */
> +
> +/* ---- IMX908 Common Register List ---- */
> +static const struct cci_reg_sequence imx908_common_regs[] = {
> +	{ IMX908_XXS_DRV, IMX908_CONTROLLER_MODE },
> +	{ CCI_REG8(0x039c), 0x03 },
> +	{ CCI_REG8(0x3416), 0x20 },
> +	{ CCI_REG8(0x3417), 0x00 },
> +	{ CCI_REG8(0x3456), 0xf4 },
> +	{ CCI_REG8(0x345d), 0x01 },
> +	{ CCI_REG8(0x3460), 0x00 },
> +	{ CCI_REG8(0x3461), 0x0b },
> +	{ CCI_REG8(0x3471), 0x00 },
> +	{ CCI_REG8(0x3472), 0x23 },
> +	{ CCI_REG8(0x347b), 0x02 },
> +	{ CCI_REG8(0x3481), 0x01 },
> +	{ CCI_REG8(0x380c), 0x00 },
> +	{ CCI_REG8(0x380f), 0x0c },
> +	{ CCI_REG8(0x381c), 0x11 },
> +	{ CCI_REG8(0x3820), 0x22 },
> +	{ CCI_REG8(0x3824), 0x33 },
> +	{ CCI_REG8(0x3828), 0x22 },
> +	{ CCI_REG8(0x382c), 0x33 },
> +	{ CCI_REG8(0x3830), 0x33 },
> +	{ CCI_REG8(0x3838), 0x05 },
> +	{ CCI_REG8(0x383c), 0x07 },
> +	{ CCI_REG8(0x3840), 0x06 },
> +	{ CCI_REG8(0x3848), 0x17 },
> +	{ CCI_REG8(0x384c), 0x0b },
> +	{ CCI_REG8(0x3850), 0x10 },
> +	{ CCI_REG8(0x3854), 0x12 },
> +	{ CCI_REG8(0x385c), 0x20 },
> +	{ CCI_REG8(0x38c4), 0x64 },
> +	{ CCI_REG8(0x38c5), 0x64 },
> +	{ CCI_REG8(0x38c6), 0x64 },
> +	{ CCI_REG8(0x3c4a), 0x15 },
> +	{ CCI_REG8(0x3c4c), 0x13 },
> +	{ CCI_REG8(0x3c4d), 0x13 },
> +	{ CCI_REG8(0x3c4e), 0x13 },
> +	{ CCI_REG8(0x3c50), 0x77 },
> +	{ CCI_REG8(0x3c51), 0x07 },
> +	{ CCI_REG8(0x3db4), 0x00 },
> +	{ CCI_REG8(0x4419), 0x06 },
> +	{ CCI_REG8(0x441c), 0x00 },
> +	{ CCI_REG8(0x4426), 0x00 },
> +	{ CCI_REG8(0x4538), 0x20 },
> +	{ CCI_REG8(0x4539), 0x19 },
> +	{ CCI_REG8(0x453a), 0x19 },
> +	{ CCI_REG8(0x453b), 0x19 },
> +	{ CCI_REG8(0x453c), 0x19 },
> +	{ CCI_REG8(0x453d), 0x19 },
> +	{ CCI_REG8(0x453e), 0x19 },
> +	{ CCI_REG8(0x453f), 0x19 },
> +	{ CCI_REG8(0x4540), 0x19 },
> +	{ CCI_REG8(0x4544), 0x11 },
> +	{ CCI_REG8(0x4545), 0x11 },
> +	{ CCI_REG8(0x4546), 0x11 },
> +	{ CCI_REG8(0x463c), 0x20 },
> +	{ CCI_REG8(0x465e), 0xcf },
> +	{ CCI_REG8(0x4684), 0x20 },
> +	{ CCI_REG8(0x46a6), 0xcf },
> +	{ CCI_REG8(0x46e2), 0xf3 },
> +};
> +
> +static const u32 tuning_regs[] = {
> +	CCI_REG8(0x3d78),
> +	CCI_REG8(0x3d79),
> +	CCI_REG8(0x3d80),
> +	CCI_REG8(0x3d81),
> +	CCI_REG8(0x3d88),
> +	CCI_REG8(0x3d89),
> +	CCI_REG8(0x3d90),
> +	CCI_REG8(0x3d91),
> +};
> +
> +#define IMX908_EXPOSURE_MIN	1
> +#define IMX908_EXPOSURE_STEP	1
> +
> +/* ---- Speed of internal clock */
> +#define IMX908_XHS_HZ		74250000ULL
> +
> +/* ---- Subdev Pads */
> +#define IMX908_SOURCE_PAD	0
> +
> +#define IMX908_DEFAULT_MBUS_CODE MEDIA_BUS_FMT_SRGGB10_1X10
> +
> +/* IMX908 total area includes effective area plus

This should be

/*
 * IMX908 total area includes effective area plus

> + * 10 effective OB pixels in vertical direction,
> + * 10 pixels OB side ignored area in height
> + */
> +static const struct v4l2_rect imx908_total_area = {
> +	.top = 0,
> +	.left = 0,
> +	.width = 3856,
> +	.height = 2200,
> +};
> +
> +static const struct v4l2_rect imx908_active_area = {
> +	.top = 0,
> +	.left = 0,
> +	.width = 3856,
> +	.height = 2176,
> +};
> +
> +/* Recommended 4K recording area centered within the active area */
> +static const struct v4l2_rect imx908_recording_area = {
> +	.top = 8,
> +	.left = 8,
> +	.width = 3840,
> +	.height = 2160,
> +};
> +
> +static const char *const imx908_supply_names[] = {
> +	"avdd",  /* Analog (3.3V) supply */
> +	"dvdd",  /* Digital Core (1.1V) supply */
> +	"ovdd",  /* IF (1.8V) supply */
> +};
> +
> +static const u32 imx908_mbus_codes[] = {
> +	MEDIA_BUS_FMT_SRGGB10_1X10, /* RAW10 */
> +	MEDIA_BUS_FMT_SRGGB12_1X12, /* RAW12 */
> +};
> +
> +enum {
> +	IMX908_LINK_FREQ_297MHZ,
> +	IMX908_LINK_FREQ_360MHZ,
> +	IMX908_LINK_FREQ_445MHZ,
> +	IMX908_LINK_FREQ_594MHZ,
> +	IMX908_LINK_FREQ_720MHZ,
> +	IMX908_LINK_FREQ_891MHZ,
> +	IMX908_LINK_FREQ_1039MHZ,
> +	IMX908_LINK_FREQ_1188MHZ,
> +};
> +
> +static const u64 imx908_link_freqs[] = {
> +	[IMX908_LINK_FREQ_297MHZ]  =  297000000ULL,
> +	[IMX908_LINK_FREQ_360MHZ]  =  360000000ULL,
> +	[IMX908_LINK_FREQ_445MHZ]  =  445000000ULL,
> +	[IMX908_LINK_FREQ_594MHZ]  =  594000000ULL,
> +	[IMX908_LINK_FREQ_720MHZ]  =  720000000ULL,
> +	[IMX908_LINK_FREQ_891MHZ]  =  891000000ULL,
> +	[IMX908_LINK_FREQ_1039MHZ] = 1039500000ULL,
> +	[IMX908_LINK_FREQ_1188MHZ] = 1188000000ULL,
> +};
> +
> +/* DDR lane_rate (Mbps/lane) = 2 x link_freq (Hz) / 1e6 */
> +static const u8 imx908_datarate_sel[] = {
> +	[IMX908_LINK_FREQ_297MHZ]  = 0x07, /*  594 Mbps */
> +	[IMX908_LINK_FREQ_360MHZ]  = 0x06, /*  720 Mbps */
> +	[IMX908_LINK_FREQ_445MHZ]  = 0x05, /*  891 Mbps */
> +	[IMX908_LINK_FREQ_594MHZ]  = 0x04, /* 1188 Mbps */
> +	[IMX908_LINK_FREQ_720MHZ]  = 0x03, /* 1440 Mbps */
> +	[IMX908_LINK_FREQ_891MHZ]  = 0x02, /* 1782 Mbps */
> +	[IMX908_LINK_FREQ_1039MHZ] = 0x01, /* 2079 Mbps */
> +	[IMX908_LINK_FREQ_1188MHZ] = 0x00, /* 2376 Mbps */
> +};
> +
> +struct imx908_inck_cfg {
> +	u32 xclk_hz;
> +	u8  inck_sel;
> +};
> +
> +/* Allowed clock values in Hz */
> +static const u32 imx908_inck_table[] = {
> +	74250000,
> +	37125000,
> +	72000000,
> +	27000000,
> +	24000000,
> +};
> +
> +struct imx908_mode {
> +	/* Sensor timing */
> +	u16 hmax;	/* clocks per line */
> +	u32 vmax;	/* lines per frame */
> +
> +	/* Derived values */
> +	u64 pixel_rate;
> +};

This structure should be dropped. It will be easier to do with a
hardcoded pixel_rate value (see below), but should be done even if we
decide to keep the pixel rate dynamic. I can give it a try based on v2
of the driver if you're having trouble.

> +
> +struct imx908 {
> +	/* Core V4L2 objects */
> +	struct v4l2_subdev sd;
> +	struct media_pad pad;
> +	struct device *dev;
> +
> +	struct regmap *cci;
> +
> +	/* Hardware resources */
> +	struct clk *xclk;
> +	struct gpio_desc *reset_gpio;
> +	struct regulator_bulk_data supplies[ARRAY_SIZE(imx908_supply_names)];
> +
> +	/* Clock configuration */
> +	u32 xclk_freq;
> +	u8  inck_sel;
> +
> +	/* Link/bus configuration */
> +	u8 num_lanes;
> +	unsigned long link_freq_bitmap;
> +	unsigned int link_freq_idx;
> +
> +	struct imx908_mode mode; /* Current mode */
> +
> +	/* V4L2 controls */
> +	struct {
> +		struct v4l2_ctrl_handler handler;
> +
> +		struct v4l2_ctrl *pixel_rate;
> +		struct v4l2_ctrl *exposure;
> +		struct v4l2_ctrl *vblank;
> +		struct v4l2_ctrl *hblank;
> +		struct v4l2_ctrl *test_pattern;
> +	} ctrls;
> +};
> +
> +static inline struct imx908 *to_imx908(struct v4l2_subdev *_sd)
> +{
> +	return container_of(_sd, struct imx908, sd);
> +}
> +
> +/* ----------------------- Basic Helper Functions ---------------------------- */
> +
> +/* Compute pixel-rate from link-freq/lanes/bpp */
> +static inline u64 imx908_pixel_rate(u8 lanes, u8 bpp, u64 linkfreq_hz)
> +{
> +	u64 total = lanes * linkfreq_hz * 2; /* DDR: 2 * linkfreq */
> +
> +	return div_u64(total, bpp);

In his IMX678 driver, Jai hardcodes the pixel rate to 594MHz, which is
8 * 74.25MHz (IMX908_XHS_HZ). The rationale is that HMAX is expressed in
units of the 74.25 MHz internal clock, so we assumed that the pixel
array is not read out using the link clock but using a clock derived
from the internal clock. The multiplier was chosen to ensure that the
minimum HMAX value corresponds to a positive HBLANK, as negative HBLANK
would confuse userspace (and developers). Having a fixed pixel rate
greatly simplifies the driver, as you don't have to update the pixel
rate control, and HMAX calculation from HBLANK becomes a division by 8.

We're not sure how the pixel array of the IMX678 is clocked exactly, so
I don't know if the above corresponds to reality, neither for the IMX678
nor the IMX908. If you could provide more information about the pixel
array readout, that would be greatly appreciated. Note that the pixel
rate value does not have to match the physical readout clock, as it is
only used by userspace to calculate timings (to convert between h/v
blank and fps).

Jai can provide more information if needed.

> +}
> +
> +static int imx908_link_freq_to_datarate_sel(struct imx908 *imx, u64 link_freq_hz, u8 *sel)
> +{
> +	for (unsigned int i = 0; i < ARRAY_SIZE(imx908_link_freqs); i++) {
> +		if (imx908_link_freqs[i] == link_freq_hz) {
> +			*sel = imx908_datarate_sel[i];
> +			return 0;
> +		}
> +	}

A blank line would be nice here.

> +	dev_err(imx->dev, "Unsupported link frequency %llu Hz\n", link_freq_hz);

The caller prints a similar error message, you can drop this one.

> +	return -EINVAL;
> +}
> +
> +static bool imx908_mbus_code_supported(struct imx908 *imx, u32 code)
> +{
> +	for (unsigned int i = 0; i < ARRAY_SIZE(imx908_mbus_codes); i++) {
> +		if (imx908_mbus_codes[i] == code)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +static u16 imx908_calc_hmax(u32 width, u32 hblank, u64 pixel_rate)
> +{
> +	u64 hmax;
> +
> +	/* HMAX is expressed in cycles of the internal 74.25 MHz clock */
> +	hmax = DIV_ROUND_UP_ULL((width + hblank) * IMX908_XHS_HZ, pixel_rate);
> +
> +	return min_t(u64, hmax, IMX908_HMAX_MAX);
> +}
> +
> +static u32 imx908_calc_vmax(u32 height, u32 vblank)
> +{
> +	return min_t(u32, height + vblank, IMX908_VMAX_MAX);
> +}
> +
> +static u16 imx908_calc_min_hmax(u32 width, u64 pixel_rate)
> +{
> +	/*
> +	 * Calculate the minimum HMAX that guarantees:
> +	 *     line_length_pixels >= width
> +	 * where:
> +	 *     line_length_pixels =
> +	 *         ceil(HMAX * pixel_rate / IMX908_XHS_HZ)
> +	 */
> +	return DIV_ROUND_UP((u64)width * IMX908_XHS_HZ, pixel_rate);
> +}
> +
> +static u32 imx908_calc_min_vmax(const struct v4l2_rect *crop)
> +{
> +	/* In window crop mode constrain VMAX (from datasheet) */
> +	if (!v4l2_rect_equal(crop, &imx908_active_area))
> +		return max(crop->height + IMX908_VMAX_CROP_MIN_MARGIN,
> +			   IMX908_VMAX_CROP_MIN_LIMIT);
> +
> +	return IMX908_VMAX_DEFAULT;
> +}
> +
> +static u32 imx908_calc_min_vblank(const struct v4l2_rect *crop)
> +{
> +	u32 min_vmax = imx908_calc_min_vmax(crop);
> +
> +	if (min_vmax <= crop->height)
> +		return 0;
> +
> +	return min_vmax - crop->height;
> +}
> +
> +static u32 imx908_calc_max_vblank(u32 height)
> +{
> +	return IMX908_VMAX_MAX - height;
> +}
> +
> +static int imx908_set_exposure_lines(struct imx908 *imx, u32 exposure_lines)
> +{
> +	u32 max_lines = imx->mode.vmax - IMX908_MIN_SHR0;
> +
> +	exposure_lines = clamp_t(u32, exposure_lines, 1, max_lines);
> +
> +	/* Calculate the shutter register value based on current VMAX */
> +	u32 shr0 = imx->mode.vmax - exposure_lines;
> +
> +	return cci_write(imx->cci, IMX908_REG_SHR0, shr0, NULL);
> +}
> +
> +static u8 imx908_bits_per_pixel(u32 code)
> +{
> +	switch (code) {
> +	case MEDIA_BUS_FMT_SRGGB12_1X12:
> +		return 12;
> +	case MEDIA_BUS_FMT_SRGGB10_1X10:
> +	default:
> +		return 10;
> +	}
> +}
> +
> +static int imx908_sync_pixel_rate_ctrl(struct imx908 *imx)
> +{
> +	s64 pixel_rate = imx->mode.pixel_rate;
> +	int ret;
> +
> +	if (!imx->ctrls.pixel_rate)
> +		return 0;
> +
> +	/* Update control range so pixel_rate is fixed (min = max = default) */
> +	__v4l2_ctrl_modify_range(imx->ctrls.pixel_rate, pixel_rate, pixel_rate,
> +				 1, pixel_rate);
> +
> +	/* Update the current control value to match the new mode pixel_rate */
> +	ret = __v4l2_ctrl_s_ctrl_int64(imx->ctrls.pixel_rate, pixel_rate);
> +	if (ret) {
> +		dev_err(imx->dev, "failed to update pixel rate control: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static u32 imx908_hmax_to_hblank(u16 hmax, u64 pixel_rate, u32 width)
> +{
> +	/* Convert HMAX to line length in pixels */
> +	u64 line_len_pixels = div_u64((u64)hmax * pixel_rate, IMX908_XHS_HZ);
> +
> +	if (line_len_pixels <= width)
> +		return 0;
> +
> +	/* Subtract active image width to obtain horizontal blanking interval */
> +	return line_len_pixels - width;
> +}
> +
> +static void imx908_update_hblank_limits(struct imx908 *imx, u32 width, u64 pixel_rate)
> +{
> +	u16 min_hmax = imx908_calc_min_hmax(width, pixel_rate);
> +	u32 min_hblank = imx908_hmax_to_hblank(min_hmax, pixel_rate, width);
> +	u32 max_hblank = imx908_hmax_to_hblank(IMX908_HMAX_MAX, pixel_rate, width);
> +	u32 hblank = imx908_hmax_to_hblank(imx->mode.hmax, pixel_rate, width);
> +
> +	hblank = clamp_t(u32, hblank, min_hblank, max_hblank);
> +
> +	__v4l2_ctrl_modify_range(imx->ctrls.hblank, min_hblank, max_hblank, 1, hblank);
> +
> +	if (imx->ctrls.hblank->val != hblank)
> +		__v4l2_ctrl_s_ctrl(imx->ctrls.hblank, hblank);
> +}
> +
> +static void imx908_update_vblank_limits(struct imx908 *imx,
> +					const struct v4l2_rect *crop)
> +{
> +	u32 min_vblank;
> +	u32 max_vblank;
> +	u32 vblank;
> +
> +	if (!imx->ctrls.vblank)
> +		return;
> +
> +	min_vblank = imx908_calc_min_vblank(crop);
> +	max_vblank = imx908_calc_max_vblank(crop->height);
> +	vblank = clamp_t(u32, imx->ctrls.vblank->val,
> +			 min_vblank, max_vblank);
> +
> +	__v4l2_ctrl_modify_range(imx->ctrls.vblank,
> +				 min_vblank,
> +				 max_vblank,
> +				 1,
> +				 vblank);
> +}
> +
> +/* ------------------ Pattern Generator (TPG) ----------------------- */
> +static const char * const imx908_tpg_menu[] = {
> +	"Disabled",
> +	"All 000h",
> +	"All FFFh",
> +	"All 555h",
> +	"All AAAh",
> +	"555h / AAAh Toggle",
> +	"AAAh / 555h Toggle",
> +	"000h / 555h Toggle",
> +	"555h / 000h Toggle",
> +	"000h / FFFh Toggle",
> +	"FFFh / 000h Toggle",
> +	"Horiz Color Bars",
> +	"Vert Color Bars",
> +};
> +
> +static int imx908_update_test_pattern(struct imx908 *imx, u32 index)
> +{
> +	int ret = 0;
> +
> +	if (index == 0) {
> +		/* Picture (not TPG) output setting */
> +		cci_update_bits(imx->cci, IMX908_REG_TPG_EN, IMX908_TPG_EN_BIT,
> +				0x00, &ret);
> +
> +		/* Disable TESTCLKEN (write-only register) */
> +		cci_write(imx->cci, IMX908_REG_TESTCLKEN, 0x00, &ret);
> +
> +		return ret;
> +	}
> +
> +	cci_write(imx->cci, IMX908_REG_TESTCLKEN, IMX908_TESTCLKEN_BIT, &ret);
> +	cci_write(imx->cci, IMX908_REG_TPG_PATSEL, index - 1, &ret);
> +	cci_update_bits(imx->cci, IMX908_REG_TPG_EN, IMX908_TPG_EN_BIT,
> +			IMX908_TPG_EN_BIT, &ret);
> +
> +	return ret;
> +}
> +
> +/* -------------------- Mode Building ----------------------- */
> +static void imx908_mode_build(struct imx908 *imx,
> +			      const struct v4l2_mbus_framefmt *fmt,
> +			      const struct v4l2_rect *crop)
> +{
> +	struct imx908_mode *m = &imx->mode;
> +	u8 bpp = imx908_bits_per_pixel(fmt->code);
> +	u64 link_freq = imx908_link_freqs[imx->link_freq_idx];
> +
> +	m->pixel_rate = imx908_pixel_rate(imx->num_lanes, bpp, link_freq);
> +
> +	/* --- H timing (HMAX) --- */
> +	if (v4l2_rect_equal(crop, &imx908_active_area)) {
> +		/* Update HBLANK HMAX in all pixel mode */
> +		u16 min_hmax = imx908_calc_min_hmax(fmt->width, m->pixel_rate);
> +		u32 min_hblank = imx908_hmax_to_hblank(min_hmax, m->pixel_rate,
> +						       fmt->width);
> +		u32 max_hblank = imx908_hmax_to_hblank(IMX908_HMAX_MAX,
> +						       m->pixel_rate, fmt->width);
> +		u32 hblank = clamp_t(u32, imx->ctrls.hblank->val, min_hblank,
> +				     max_hblank);
> +		m->hmax = imx908_calc_hmax(fmt->width, hblank, m->pixel_rate);
> +	} else if (!m->hmax) {
> +		u32 hblank = imx908_hmax_to_hblank(IMX908_HMAX_DEFAULT,
> +						   m->pixel_rate,
> +						   imx908_active_area.width);
> +
> +		m->hmax = imx908_calc_hmax(fmt->width, hblank, m->pixel_rate);
> +	}
> +
> +	/* --- V timing (VMAX) --- */
> +	u32 min_vblank = imx908_calc_min_vblank(crop);
> +	u32 max_vblank = imx908_calc_max_vblank(fmt->height);
> +
> +	u32 vblank = clamp_t(u32,
> +			 imx->ctrls.vblank->val,
> +			 min_vblank,
> +			 max_vblank);
> +
> +	m->vmax = imx908_calc_vmax(fmt->height, vblank);
> +
> +	u64 line_length_pixels = div_u64((u64)m->hmax * m->pixel_rate, IMX908_XHS_HZ);
> +
> +	if (line_length_pixels < fmt->width)
> +		dev_warn(imx->dev, "Invalid timing (line=%llu < width=%u)\n",
> +			 line_length_pixels, fmt->width);
> +}
> +
> +static void imx908_update_framing_limits(struct imx908 *imx, struct v4l2_subdev_state *state)

Please wrap the line.

> +{
> +	const struct v4l2_mbus_framefmt *fmt;
> +	const struct v4l2_rect *crop;
> +
> +	fmt = v4l2_subdev_state_get_format(state, IMX908_SOURCE_PAD);
> +	crop = v4l2_subdev_state_get_crop(state, IMX908_SOURCE_PAD);
> +
> +	u8 bpp = imx908_bits_per_pixel(fmt->code);
> +	u64 link_freq = imx908_link_freqs[imx->link_freq_idx];
> +	u64 pixel_rate = imx908_pixel_rate(imx->num_lanes, bpp, link_freq);
> +
> +	/* Only update HBLANK in all pixel mode */
> +	if (v4l2_rect_equal(crop, &imx908_active_area))
> +		imx908_update_hblank_limits(imx, fmt->width, pixel_rate);
> +
> +	imx908_update_vblank_limits(imx, crop);
> +
> +	/* Build mode so cached timing uses current control values */
> +	imx908_mode_build(imx, fmt, crop);
> +
> +	/* Exposure handling */
> +	__v4l2_ctrl_modify_range(imx->ctrls.exposure,
> +				 1,
> +				 imx->mode.vmax - IMX908_MIN_SHR0,
> +				 1,
> +				 min_t(u32, imx->ctrls.exposure->val,
> +				       imx->mode.vmax - IMX908_MIN_SHR0));
> +}
> +
> +/* ----------------------- HW Programming ---------------------- */
> +
> +static int imx908_mode_apply(struct imx908 *imx,
> +			     const struct v4l2_mbus_framefmt *fmt)
> +{
> +	int ret = 0;
> +	u8 adbit, mdbit;
> +
> +	switch (fmt->code) {
> +	case MEDIA_BUS_FMT_SRGGB12_1X12:
> +		adbit = IMX908_ADBIT_12BIT;
> +		mdbit = IMX908_MDBIT_RAW12;
> +		break;
> +
> +	case MEDIA_BUS_FMT_SRGGB10_1X10:
> +	default:
> +		adbit = IMX908_ADBIT_10BIT;
> +		mdbit = IMX908_MDBIT_RAW10;
> +		break;
> +	}
> +
> +	cci_write(imx->cci, IMX908_REG_XMASTER, IMX908_CONTROLLER_MODE, &ret);
> +	cci_write(imx->cci, IMX908_REG_ADBIT, adbit, &ret);
> +	cci_write(imx->cci, IMX908_REG_MDBIT, mdbit, &ret);
> +	if (ret) {
> +		dev_err(imx->dev, "Mode register write failed: %d\n", ret);
> +		return ret;
> +	}

You can drop the error check here.

> +
> +	/* Tuning registers that need to be changed for RAW10/10-bit */
> +	u16 value = adbit == IMX908_ADBIT_10BIT &&
> +		    mdbit == IMX908_MDBIT_RAW10 ? 0x0c : 0x05;
> +
> +	for (unsigned int i = 0; i < ARRAY_SIZE(tuning_regs); ++i)
> +		cci_write(imx->cci, tuning_regs[i], value, &ret);
> +
> +	if (ret) {
> +		dev_err(imx->dev, "Tuning register write failed: %d\n", ret);
> +		return ret;
> +	}

And this one too.

> +
> +	/* INCK */
> +	cci_write(imx->cci, IMX908_REG_INCK_SEL, imx->inck_sel, &ret);
> +	if (ret) {
> +		dev_err(imx->dev, "INCK register write failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* MIPI lane rate selections */
> +	u8 datarate_sel;
> +	u64 link_freq = imx908_link_freqs[imx->link_freq_idx];
> +
> +	ret = imx908_link_freq_to_datarate_sel(imx, link_freq, &datarate_sel);
> +	if (ret) {
> +		dev_err(imx->dev, "Unsupported link_freq=%llu for DATARATE_SEL\n",
> +			link_freq);
> +		return ret;
> +	}

The link frequency is validated at probe time, so the
imx908_link_freq_to_datarate_sel() can never return an error. Drop error
checking here too.

> +	cci_write(imx->cci, IMX908_REG_DATARATE_SEL, datarate_sel, &ret);
> +
> +	/* Lane config */
> +	cci_write(imx->cci, IMX908_REG_LANEMODE, imx->num_lanes - 1, &ret);
> +	if (ret) {
> +		dev_err(imx->dev, "Clock/lane configuration failed: %d\n", ret);
> +		return ret;
> +	}

Drop this error check here too.

> +
> +	/* Recommended black level offset is 50 in 10-bit, 200 for others */
> +	u16 blklevel = (mdbit == IMX908_MDBIT_RAW10) ? 50 : 200;
> +
> +	cci_write(imx->cci, IMX908_REG_BLKLEVEL, blklevel, &ret);
> +
> +	return ret;

The error is propagated through the chained cci_write() calls and
handled here. That's all you need, cci_write() will print a message on
failure, with the register address and value.

> +}
> +
> +static int imx908_program_window(struct imx908 *imx, const struct v4l2_rect *crop)
> +{
> +	bool all_pixel_mode = v4l2_rect_equal(crop, &imx908_active_area);
> +	int ret = 0;
> +
> +	cci_write(imx->cci, IMX908_REG_WINMODE,
> +		  all_pixel_mode ? IMX908_WINMODE_ALLPIX : IMX908_WINMODE_CROP,
> +		  &ret);
> +
> +	/* Update window size in window crop mode */
> +	if (!all_pixel_mode) {
> +		cci_write(imx->cci, IMX908_REG_PIX_HST,    crop->left,   &ret);
> +		cci_write(imx->cci, IMX908_REG_PIX_HWIDTH, crop->width,  &ret);
> +		cci_write(imx->cci, IMX908_REG_PIX_VST,    crop->top,    &ret);
> +		cci_write(imx->cci, IMX908_REG_PIX_VWIDTH, crop->height, &ret);
> +	}
> +
> +	return ret;
> +}
> +
> +/* ----------------------- Start/Stop streaming ---------------------- */
> +
> +static int imx908_start_streaming(struct imx908 *imx)
> +{
> +	struct v4l2_subdev_state *sd_state;
> +	const struct v4l2_rect *crop;
> +	const struct v4l2_mbus_framefmt *format;
> +	int ret = 0;
> +
> +	/* Get active state */
> +	sd_state = v4l2_subdev_get_locked_active_state(&imx->sd);

The caller already has the active state, pass it as an argument to the
imx908_start_streaming() function.

> +	crop = v4l2_subdev_state_get_crop(sd_state, IMX908_SOURCE_PAD);
> +	format = v4l2_subdev_state_get_format(sd_state, IMX908_SOURCE_PAD);
> +
> +	/* Build the mode based on active state before streaming */
> +	imx908_mode_build(imx, format, crop);
> +
> +	/* Write common registers: static sensor tuning only */
> +	cci_multi_reg_write(imx->cci, imx908_common_regs,
> +			    ARRAY_SIZE(imx908_common_regs), &ret);
> +	if (ret)
> +		return ret;
> +
> +	/* HW write all other registers (which depend on mode) */
> +	ret = imx908_mode_apply(imx, format);
> +	if (ret)
> +		return ret;
> +
> +	/* Geometry */
> +	ret = imx908_program_window(imx, crop);
> +	if (ret)
> +		return ret;
> +
> +	/* Apply the current control values */
> +	ret = __v4l2_ctrl_handler_setup(imx->sd.ctrl_handler);
> +	if (ret)
> +		return ret;
> +
> +	/* Cancel standby state */
> +	cci_write(imx->cci, IMX908_REG_STANDBY, IMX908_STANDBY_CANCEL, &ret);
> +	msleep(24); /* SRM >=24 ms regulator stabilization after standby cancel */
> +
> +	/* Start controller mode */
> +	cci_write(imx->cci, IMX908_REG_XMSTA, IMX908_START_CONTROLLER, &ret);
> +	return ret;
> +}
> +
> +static int imx908_stop_streaming(struct imx908 *imx)
> +{
> +	int ret = 0;
> +
> +	cci_write(imx->cci, IMX908_REG_STANDBY, IMX908_STANDBY_EN, &ret);
> +	cci_write(imx->cci, IMX908_REG_XMSTA, IMX908_STOP_CONTROLLER, &ret);
> +	return ret;
> +}
> +
> +/* --------------------------- V4L2 controls ------------------------------ */
> +
> +static int imx908_set_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +	struct imx908 *imx = container_of(ctrl->handler, struct imx908, ctrls.handler);
> +	struct v4l2_subdev_state *state;
> +	struct i2c_client *client = v4l2_get_subdevdata(&imx->sd);
> +	const struct v4l2_mbus_framefmt *format;
> +	int ret = 0;
> +
> +	/* Retrieve the active, locked subdev state format dimensions */
> +	state = v4l2_subdev_get_locked_active_state(&imx->sd);
> +	format = v4l2_subdev_state_get_format(state, IMX908_SOURCE_PAD);
> +
> +	/* Applying V4L2 controls only if powered up */
> +	if (!pm_runtime_get_if_in_use(&client->dev))

	if (!pm_runtime_get_if_in_use(imx->dev))

and similarly below, and drop the client local variable.

> +		return 0;
> +
> +	switch (ctrl->id) {
> +	case V4L2_CID_EXPOSURE: {
> +		u32 lines = clamp_t(u32, ctrl->val, 1,
> +				    imx->mode.vmax - IMX908_MIN_SHR0);

Drop this, the control framework already clamps to the limits.

> +
> +		ret = imx908_set_exposure_lines(imx, lines);
> +		break;
> +	}
> +
> +	case V4L2_CID_ANALOGUE_GAIN:
> +

Drop this blank line.

> +		u32 reg = clamp_t(u32, ctrl->val, IMX908_ANA_GAIN_MIN,
> +				  IMX908_ANA_GAIN_MAX);

Drop this, the control framework already clamps to the limits.

> +
> +		cci_write(imx->cci, IMX908_REG_GAIN, reg, &ret);
> +		break;
> +
> +	case V4L2_CID_VBLANK: {
> +		const struct v4l2_rect *crop;
> +
> +		crop = v4l2_subdev_state_get_crop(state, IMX908_SOURCE_PAD);
> +
> +		u32 min_vblank = imx908_calc_min_vblank(crop);
> +		u32 max_vblank = imx908_calc_max_vblank(format->height);
> +		u32 vblank = clamp_t(u32, ctrl->val, min_vblank, max_vblank);
> +
> +		imx->mode.vmax = imx908_calc_vmax(format->height, vblank);
> +
> +		u32 exposure = min_t(u32, imx->ctrls.exposure->val,
> +				     imx->mode.vmax - IMX908_MIN_SHR0);
> +
> +		__v4l2_ctrl_modify_range(imx->ctrls.exposure,
> +					 IMX908_EXPOSURE_MIN,
> +					 imx->mode.vmax - IMX908_MIN_SHR0,
> +					 IMX908_EXPOSURE_STEP, exposure);

All the the above should go before the pm_runtime_get_if_in_use() call,
as the exposure control limits needs to be updated even if the sensor
isn't streaming. You can add a

	if (ctrl->id == V4L2_CID_VBLANK) {
		...
	}

block there.

> +
> +		ret = cci_write(imx->cci, IMX908_REG_VMAX,
> +				imx->mode.vmax, NULL);
> +		if (!ret)
> +			ret = imx908_set_exposure_lines(imx, exposure);
> +
> +		break;
> +	}
> +
> +	case V4L2_CID_HBLANK: {
> +		u16 hmax;
> +		u32 width = format->width;
> +		u64 pixel_rate = imx->mode.pixel_rate;
> +		const struct v4l2_rect *crop;
> +
> +		crop = v4l2_subdev_state_get_crop(state, IMX908_SOURCE_PAD);
> +
> +		/* Ignore HBLANK update in window crop mode */
> +		if (!v4l2_rect_equal(crop, &imx908_active_area))
> +			break;
> +
> +		/* Skip timing calculation when not initialized */
> +		if (!pixel_rate || !width)
> +			break;
> +
> +		/* Recompute hmax based on HBLANK */
> +		hmax = imx908_calc_hmax(width, ctrl->val, pixel_rate);
> +		imx->mode.hmax = hmax;
> +		cci_write(imx->cci, IMX908_REG_HMAX, hmax, &ret);
> +		break;
> +	}
> +
> +	case V4L2_CID_PIXEL_RATE:
> +	case V4L2_CID_LINK_FREQ:
> +		break;
> +
> +	case V4L2_CID_TEST_PATTERN:
> +		ret = imx908_update_test_pattern(imx, ctrl->val);
> +		break;
> +
> +	case V4L2_CID_HFLIP:
> +		cci_write(imx->cci, IMX908_REG_HREVERSE, ctrl->val, &ret);
> +		break;
> +
> +	case V4L2_CID_VFLIP:
> +		cci_write(imx->cci, IMX908_REG_VREVERSE, ctrl->val, &ret);
> +		break;
> +
> +	default:
> +		dev_warn(&client->dev,
> +			 "ctrl(id:0x%x,val:0x%x) is not handled\n",
> +			 ctrl->id, ctrl->val);
> +		break;
> +	}
> +
> +	pm_runtime_put(&client->dev);
> +	return ret;
> +}
> +
> +static const struct v4l2_ctrl_ops imx908_ctrl_ops = {
> +	.s_ctrl = imx908_set_ctrl,
> +};
> +
> +/* ------------------------ Pad/video ops ------------------ */
> +
> +static int imx908_enum_mbus_code(struct v4l2_subdev *sd,
> +				 struct v4l2_subdev_state *sd_state,
> +				 struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	if (code->index >= ARRAY_SIZE(imx908_mbus_codes))
> +		return -EINVAL;
> +	code->code = imx908_mbus_codes[code->index];
> +	return 0;
> +}
> +
> +static int imx908_enum_frame_size(struct v4l2_subdev *sd,
> +				  struct v4l2_subdev_state *sd_state,
> +				  struct v4l2_subdev_frame_size_enum *fse)
> +{
> +	const struct v4l2_rect *crop = v4l2_subdev_state_get_crop(sd_state, IMX908_SOURCE_PAD);
> +	struct imx908 *imx = to_imx908(sd);
> +
> +	if (fse->index > 0)
> +		return -EINVAL;
> +
> +	if (!imx908_mbus_code_supported(imx, fse->code))
> +		return -EINVAL;
> +
> +	fse->min_width  = crop->width;
> +	fse->max_width  = crop->width;
> +	fse->min_height = crop->height;
> +	fse->max_height = crop->height;
> +
> +	return 0;
> +}
> +
> +static int imx908_set_pad_format(struct v4l2_subdev *sd,
> +				 struct v4l2_subdev_state *sd_state,
> +				 struct v4l2_subdev_format *fmt)
> +{
> +	struct imx908 *imx = to_imx908(sd);
> +	struct v4l2_mbus_framefmt *format;
> +	int ret = 0;
> +
> +	if (fmt->which == V4L2_SUBDEV_FORMAT_ACTIVE && v4l2_subdev_is_streaming(sd))
> +		return -EBUSY;
> +
> +	format = v4l2_subdev_state_get_format(sd_state, fmt->pad);
> +
> +	if (imx908_mbus_code_supported(imx, fmt->format.code))
> +		format->code = fmt->format.code;
> +	else
> +		format->code = IMX908_DEFAULT_MBUS_CODE;
> +
> +	/* Fully define metadata */
> +	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;
> +
> +	/* Update pixel rate range and hblank (ACTIVE ONLY) */
> +	if (fmt->which == V4L2_SUBDEV_FORMAT_ACTIVE) {
> +		imx908_update_framing_limits(imx, sd_state);
> +		ret = imx908_sync_pixel_rate_ctrl(imx);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	/* Return final applied format to userspace */
> +	fmt->format = *format;
> +
> +	return 0;
> +}
> +
> +static int imx908_set_selection(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_state *sd_state,
> +				struct v4l2_subdev_selection *sel)
> +{
> +	struct imx908 *imx = to_imx908(sd);
> +	struct v4l2_rect *crop; /* current crop rectangle in subdev state */
> +	struct v4l2_rect *r = &sel->r;
> +	struct v4l2_mbus_framefmt *format;
> +
> +	if (sel->target != V4L2_SEL_TGT_CROP)
> +		return -EINVAL;
> +
> +	if (sel->which == V4L2_SUBDEV_FORMAT_ACTIVE && v4l2_subdev_is_streaming(sd))
> +		return -EBUSY;
> +
> +	crop = v4l2_subdev_state_get_crop(sd_state, sel->pad);
> +	format = v4l2_subdev_state_get_format(sd_state, sel->pad);
> +
> +	/*
> +	 * Round the crop rectangle size down to the hardware alignment
> +	 * constraints, then clamp it to the supported size range.
> +	 */
> +	r->width = clamp_t(s32, ALIGN_DOWN(r->width, IMX908_CROP_ALIGN_HWIDTH),
> +			   IMX908_CROP_MIN_WIDTH, imx908_active_area.width);
> +	r->height = clamp_t(s32, ALIGN_DOWN(r->height, IMX908_CROP_ALIGN_VWIDTH),
> +			    IMX908_CROP_MIN_HEIGHT, imx908_active_area.height);
> +
> +	/*
> +	 * Round and clamp the crop position similarly, with the maximum value
> +	 * chosen so that the crop rectangle remains fully inside the active
> +	 * pixel array.
> +	 */
> +	r->left = clamp_t(s32, ALIGN_DOWN(r->left, IMX908_CROP_ALIGN_HSTART), 0,
> +			  imx908_active_area.width - r->width);
> +	r->top = clamp_t(s32, ALIGN_DOWN(r->top, IMX908_CROP_ALIGN_VSTART), 0,
> +			 imx908_active_area.height - r->height);
> +
> +	/* Update the crop rectangle in subdev state */
> +	*crop = *r;
> +
> +	/* Binning is not supported in IMX908 sensor */
> +	format->width  = crop->width;
> +	format->height = crop->height;
> +
> +	if (sel->which == V4L2_SUBDEV_FORMAT_ACTIVE)
> +		imx908_update_framing_limits(imx, sd_state);
> +
> +	return 0;
> +}
> +
> +static int imx908_get_selection(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_state *sd_state,
> +				struct v4l2_subdev_selection *sel)
> +{
> +	switch (sel->target) {
> +	case V4L2_SEL_TGT_CROP:
> +		sel->r = *v4l2_subdev_state_get_crop(sd_state, IMX908_SOURCE_PAD);
> +		return 0;
> +
> +	case V4L2_SEL_TGT_NATIVE_SIZE:
> +		sel->r = imx908_total_area;
> +		return 0;
> +
> +	case V4L2_SEL_TGT_CROP_DEFAULT:
> +		sel->r = imx908_recording_area;
> +		return 0;
> +
> +	case V4L2_SEL_TGT_CROP_BOUNDS:
> +		sel->r = imx908_active_area;
> +		return 0;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int imx908_enable_streams(struct v4l2_subdev *sd,
> +				 struct v4l2_subdev_state *sd_state,
> +				 u32 pad,
> +				 u64 streams_mask)
> +{
> +	struct imx908 *imx = to_imx908(sd);
> +	int ret;
> +
> +	ret = pm_runtime_resume_and_get(imx->dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = imx908_start_streaming(imx);
> +	if (ret) {
> +		pm_runtime_mark_last_busy(imx->dev);
> +		pm_runtime_put_autosuspend(imx->dev);

I would add

		return ret;

> +	}
> +
> +	return ret;

and here write

	return 0;

to clearly isolate the error path from the success path.

That's a personal preference though, up to you.

> +}
> +
> +static int imx908_disable_streams(struct v4l2_subdev *sd,
> +				  struct v4l2_subdev_state *sd_state,
> +				  u32 pad,
> +				  u64 streams_mask)
> +{
> +	struct imx908 *imx = to_imx908(sd);
> +	int ret;
> +
> +	ret = imx908_stop_streaming(imx);
> +
> +	pm_runtime_mark_last_busy(imx->dev);
> +	pm_runtime_put_autosuspend(imx->dev);
> +
> +	return ret;
> +}
> +
> +static int imx908_init_state(struct v4l2_subdev *sd,
> +			     struct v4l2_subdev_state *sd_state)
> +{
> +	int ret = 0;
> +	struct v4l2_subdev_selection sel = {
> +		.which  = V4L2_SUBDEV_FORMAT_TRY,
> +		.pad    = IMX908_SOURCE_PAD,
> +		.target = V4L2_SEL_TGT_CROP,
> +		.r      = imx908_active_area,
> +	};
> +	struct v4l2_subdev_format fmt = {
> +		.which = V4L2_SUBDEV_FORMAT_TRY,
> +		.pad   = IMX908_SOURCE_PAD,
> +		.format = {
> +			.code   = IMX908_DEFAULT_MBUS_CODE,
> +			.width  = imx908_active_area.width,
> +			.height = imx908_active_area.height,
> +		},
> +	};
> +
> +	ret = imx908_set_selection(sd, sd_state, &sel);
> +	ret = imx908_set_pad_format(sd, sd_state, &fmt);

Those two functions return errors only when called with invalid
arguments. Invalid .which, .pad or .target values in sel or fmt would be
driver bugs, so I think it's safe to not check for errors. You shouldn't
assign ret, and you can

	return 0;

> +
> +	return ret;
> +}
> +
> +static const struct v4l2_subdev_core_ops imx908_core_ops = {
> +	.subscribe_event   = v4l2_ctrl_subdev_subscribe_event,
> +	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
> +};
> +
> +static const struct v4l2_subdev_video_ops imx908_video_ops = {
> +	.s_stream = v4l2_subdev_s_stream_helper,
> +};
> +
> +static const struct v4l2_subdev_pad_ops imx908_pad_ops = {
> +	.enum_mbus_code      = imx908_enum_mbus_code,
> +	.enum_frame_size     = imx908_enum_frame_size,
> +	.get_fmt             = v4l2_subdev_get_fmt,
> +	.set_fmt             = imx908_set_pad_format,
> +	.get_selection       = imx908_get_selection,
> +	.set_selection       = imx908_set_selection,
> +	.enable_streams      = imx908_enable_streams,
> +	.disable_streams     = imx908_disable_streams,
> +};
> +
> +static const struct v4l2_subdev_internal_ops imx908_internal_ops = {
> +	.init_state = imx908_init_state,
> +};
> +
> +static const struct v4l2_subdev_ops imx908_subdev_ops = {
> +	.core  = &imx908_core_ops,
> +	.video = &imx908_video_ops,
> +	.pad   = &imx908_pad_ops,
> +};
> +
> +/* ----------------------- Power management ---------------------- */
> +
> +static int imx908_power_on(struct imx908 *imx)
> +{
> +	int ret;
> +
> +	/* Power Rails */
> +	ret = regulator_bulk_enable(ARRAY_SIZE(imx908_supply_names), imx->supplies);
> +	if (ret) {
> +		dev_err(imx->dev, "%s: failed to enable regulators\n", __func__);

You can drop the "%s: " prefix, the error message is clear enough and
doesn't need the function name.

> +		return ret;
> +	}
> +	msleep(200); /* IMX908 power ok after 200ms */
> +
> +	if (imx->reset_gpio) {
> +		gpiod_set_value_cansleep(imx->reset_gpio, 1); /* XCLR low */
> +		udelay(1); /* >= 500ns T_low */
> +		gpiod_set_value_cansleep(imx->reset_gpio, 0); /* Sensor starts */
> +	}
> +
> +	/* Start INCK */
> +	ret = clk_prepare_enable(imx->xclk);
> +	if (ret) {
> +		dev_err(imx->dev, "failed to enable xclk: %d\n", ret);
> +		goto err_reset;
> +	}
> +
> +	/* T_1 >=20us delay before initial SDA/SCL  */
> +	usleep_range(20, 25);
> +
> +	return 0;
> +
> +err_reset:
> +	gpiod_set_value_cansleep(imx->reset_gpio, 1); /* assert reset */
> +	regulator_bulk_disable(ARRAY_SIZE(imx908_supply_names), imx->supplies);
> +	return ret;
> +}
> +
> +static void imx908_power_off(struct imx908 *imx)
> +{
> +	gpiod_set_value_cansleep(imx->reset_gpio, 1);
> +	clk_disable_unprepare(imx->xclk);
> +	regulator_bulk_disable(ARRAY_SIZE(imx908_supply_names), imx->supplies);
> +}
> +
> +static int imx908_runtime_resume(struct device *dev)
> +{
> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> +	struct imx908 *imx = to_imx908(sd);
> +
> +	return imx908_power_on(imx);
> +}
> +
> +static int imx908_runtime_suspend(struct device *dev)
> +{
> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> +	struct imx908 *imx = to_imx908(sd);
> +
> +	imx908_power_off(imx);
> +	return 0;
> +}
> +
> +static DEFINE_RUNTIME_DEV_PM_OPS(imx908_pm_ops,
> +				 imx908_runtime_suspend,
> +				 imx908_runtime_resume, NULL);
> +
> +/* ------------------------------- Probe/remove --------------------------- */
> +
> +static int imx908_get_inck_sel(struct imx908 *imx)
> +{
> +	for (unsigned int i = 0; i < ARRAY_SIZE(imx908_inck_table); i++) {
> +		if (imx908_inck_table[i] == imx->xclk_freq) {
> +			imx->inck_sel = i;
> +			return 0;
> +		}
> +	}
> +
> +	return dev_err_probe(imx->dev, -EINVAL, "unsupported xclk %u Hz\n", imx->xclk_freq);

	return dev_err_probe(imx->dev, -EINVAL, "unsupported xclk %u Hz\n",
			     imx->xclk_freq);

> +}
> +
> +static int imx908_get_regulators(struct imx908 *imx)
> +{
> +	for (unsigned int i = 0; i < ARRAY_SIZE(imx908_supply_names); i++)
> +		imx->supplies[i].supply = imx908_supply_names[i];
> +
> +	return devm_regulator_bulk_get(imx->dev,
> +			ARRAY_SIZE(imx908_supply_names),
> +			imx->supplies);
> +}
> +
> +static int imx908_parse_fwnode(struct imx908 *imx)
> +{
> +	struct fwnode_handle *ep;
> +	struct v4l2_fwnode_endpoint bus_cfg = {
> +		.bus_type = V4L2_MBUS_CSI2_DPHY
> +	};
> +	int ret = 0;
> +
> +	/* Get firmware node from device tree */
> +	ep = fwnode_graph_get_next_endpoint(dev_fwnode(imx->dev), NULL);
> +	if (!ep) {
> +		dev_err(imx->dev, "Failed to find endpoint in device tree\n");
> +		return -ENXIO;
> +	}
> +
> +	/* Parse properties: data-lanes, link-frequencies */
> +	ret = v4l2_fwnode_endpoint_alloc_parse(ep, &bus_cfg);
> +	fwnode_handle_put(ep);
> +	if (ret)
> +		return ret;
> +
> +	imx->num_lanes = bus_cfg.bus.mipi_csi2.num_data_lanes;
> +
> +	if (imx->num_lanes != 2 && imx->num_lanes != 4) {
> +		dev_err(imx->dev, "only 2 or 4 CSI-2 data lanes are supported (got %u)\n",
> +			imx->num_lanes);
> +		ret = -EINVAL;
> +		goto out_free;
> +	}
> +
> +	ret = v4l2_link_freq_to_bitmap(imx->dev,
> +				       bus_cfg.link_frequencies,
> +				       bus_cfg.nr_of_link_frequencies,
> +				       imx908_link_freqs,
> +				       ARRAY_SIZE(imx908_link_freqs),
> +				       &imx->link_freq_bitmap);
> +	if (ret) {
> +		dev_err(imx->dev, "Failed to parse link frequencies from DT\n");
> +		goto out_free;
> +	}
> +
> +	if (bitmap_empty(&imx->link_freq_bitmap, ARRAY_SIZE(imx908_link_freqs))) {
> +		dev_err(imx->dev,
> +			"No common link frequencies between driver and DT\n");
> +		ret = -EINVAL;
> +		goto out_free;
> +	}
> +
> +	imx->link_freq_idx = __ffs(imx->link_freq_bitmap);
> +
> +out_free:
> +	v4l2_fwnode_endpoint_free(&bus_cfg);
> +	return ret;
> +}
> +
> +static int imx908_init_controls(struct imx908 *imx)
> +{
> +	struct v4l2_ctrl_handler *hdl = &imx->ctrls.handler;
> +	struct v4l2_ctrl *link_freq_ctl;
> +	struct v4l2_fwnode_device_properties props;
> +	int ret;
> +	s32 hblank, min_hblank;
> +	u32 max_exp, max_hblank, min_vblank, max_vblank;
> +	u16 min_hmax;

We tend to follow a "reverse christmas tree" order for variable
declaration (it's one of those coding style rules that aim at increasing
consistency but are otherwise completely arbitrary).

	u32 max_exp, max_hblank, min_vblank, max_vblank;
	s32 hblank, min_hblank;
	u16 min_hmax;
	int ret;

I think hblank and min_hblank can be u32, as they're calculated below
with imx908_hmax_to_hblank() that returns a u32.

> +
> +	ret = v4l2_ctrl_handler_init(hdl, 11);
> +	if (ret)
> +		return ret;
> +
> +	/* Initialize the pixel_rate control */
> +	u8 bpp = imx908_bits_per_pixel(IMX908_DEFAULT_MBUS_CODE);
> +	u64 link_freq = imx908_link_freqs[imx->link_freq_idx];
> +	u64 pixel_rate = imx908_pixel_rate(imx->num_lanes, bpp, link_freq);
> +
> +	imx->ctrls.pixel_rate = v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops, V4L2_CID_PIXEL_RATE,
> +						  pixel_rate, pixel_rate, 1, pixel_rate);
> +	if (imx->ctrls.pixel_rate)
> +		imx->ctrls.pixel_rate->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> +
> +	/* Set link Frequency */
> +	link_freq_ctl = v4l2_ctrl_new_int_menu(hdl, &imx908_ctrl_ops,
> +					       V4L2_CID_LINK_FREQ,
> +					       ARRAY_SIZE(imx908_link_freqs) - 1,
> +					       imx->link_freq_idx,
> +					       imx908_link_freqs);
> +
> +	if (link_freq_ctl)
> +		link_freq_ctl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> +
> +	/* Initialize HMAX and VMAX */
> +	imx->mode.hmax = IMX908_HMAX_DEFAULT;
> +	imx->mode.vmax = IMX908_VMAX_DEFAULT;
> +
> +	/* Set vblank */
> +	min_vblank = IMX908_VMAX_DEFAULT - imx908_active_area.height;
> +	max_vblank = imx908_calc_max_vblank(imx908_active_area.height);

As you declare the bpp, link_freq and pixel_rate variables just above
the code that uses them, instead of at the beginning of the function, I
would do the same here:

	u32 min_vblank = IMX908_VMAX_DEFAULT - imx908_active_area.height;
	u32 max_vblank = imx908_calc_max_vblank(imx908_active_area.height);

Unless Sakari has a stricter rule about declaring all variables at the
beginning of the function ?

> +
> +	imx->ctrls.vblank = v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops,
> +					      V4L2_CID_VBLANK,
> +					      min_vblank,
> +					      max_vblank,
> +					      1,
> +					      min_vblank);
> +
> +	/* Set hblank */
> +	min_hmax = imx908_calc_min_hmax(imx908_active_area.width, pixel_rate);
> +	min_hblank = imx908_hmax_to_hblank(min_hmax, pixel_rate,
> +					   imx908_active_area.width);
> +	max_hblank = imx908_hmax_to_hblank(IMX908_HMAX_MAX, pixel_rate,
> +					   imx908_active_area.width);
> +	hblank = imx908_hmax_to_hblank(IMX908_HMAX_DEFAULT, pixel_rate,
> +				       imx908_active_area.width);

Same here.

	u16 min_hmax = imx908_calc_min_hmax(imx908_active_area.width, pixel_rate);
	u32 min_hblank = imx908_hmax_to_hblank(min_hmax, pixel_rate,
					       imx908_active_area.width);
	u32 max_hblank = imx908_hmax_to_hblank(IMX908_HMAX_MAX, pixel_rate,
					       imx908_active_area.width);
	u32 hblank = imx908_hmax_to_hblank(IMX908_HMAX_DEFAULT, pixel_rate,
					   imx908_active_area.width);

> +
> +	imx->ctrls.hblank = v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops,
> +					      V4L2_CID_HBLANK,
> +					      min_hblank,
> +					      max_hblank,
> +					      1,
> +					      hblank);
> +	max_exp = imx->mode.vmax - IMX908_MIN_SHR0;

	u32 max_exp = imx->mode.vmax - IMX908_MIN_SHR0;

or better

	u32 max_exp = IMX908_VMAX_DEFAULT - IMX908_MIN_SHR0;

as that's more explicit.

> +
> +	imx->ctrls.exposure = v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops,
> +						V4L2_CID_EXPOSURE,
> +						IMX908_EXPOSURE_MIN,
> +						max_exp,
> +						IMX908_EXPOSURE_STEP,
> +						max_exp / 2);
> +
> +	v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops, V4L2_CID_ANALOGUE_GAIN,
> +			  IMX908_ANA_GAIN_MIN, IMX908_ANA_GAIN_MAX,
> +			  IMX908_ANA_GAIN_STEP, IMX908_ANA_GAIN_DEFAULT);
> +
> +	/* Set test pattern. Menu (13 entries: Disabled + 12 patterns) */
> +	imx->ctrls.test_pattern = v4l2_ctrl_new_std_menu_items(hdl,
> +							       &imx908_ctrl_ops,
> +							       V4L2_CID_TEST_PATTERN,
> +							       ARRAY_SIZE(imx908_tpg_menu) - 1,
> +							       0,
> +							       0,
> +							       imx908_tpg_menu);
> +	if (imx->ctrls.test_pattern)
> +		imx->ctrls.test_pattern->flags |= V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
> +
> +	v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops, V4L2_CID_HFLIP, 0, 1, 1, 0);
> +	v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops, V4L2_CID_VFLIP, 0, 1, 1, 0);
> +
> +	/* Pick up rotation and orientation if defined in overlay */
> +	ret = v4l2_fwnode_device_parse(imx->dev, &props);
> +	if (ret)
> +		return ret;
> +
> +	ret = v4l2_ctrl_new_fwnode_properties(hdl, &imx908_ctrl_ops, &props);
> +	if (ret)
> +		return ret;

You need to call v4l2_ctrl_handler_free() in the error path here.
Better, just drop error checking. The function sets hdl->error upon
failure, so the error check just below is enough.

> +
> +	if (hdl->error) {
> +		ret = hdl->error;
> +		v4l2_ctrl_handler_free(hdl);
> +		return ret;
> +	}
> +
> +	imx->sd.ctrl_handler = hdl;
> +
> +	return 0;
> +}
> +
> +/* Confirm the ID of the HW device */
> +static int imx908_identify_model(struct imx908 *imx)
> +{
> +	int ret;
> +	int err;
> +	u64 val;
> +	u16 chip_id;
> +
> +	/*
> +	 * The TYPE_ID registers are not accessible after power-up while
> +	 * the device remains in standby. Exit standby and wait for the
> +	 * required stabilization period before reading the chip ID.
> +	 */
> +	ret = cci_write(imx->cci, IMX908_REG_STANDBY, IMX908_STANDBY_CANCEL, NULL);
> +	if (ret)
> +		return ret;
> +
> +	msleep(24); /* Regulator stabilization after standby cancel. */
> +
> +	ret = cci_read(imx->cci, IMX908_REG_TYPE_ID, &val, &err);
> +	if (ret || err)
> +		return ret ? ret : err;

You don't need to check both ret and err. The err pointer to cci_read()
(and cci_write()) is meant to chain calls with error checking at the
end. Just check ret and pass NULL as the last argument to cci_read().

> +
> +	chip_id = val;
> +	dev_info(imx->dev, "IMX908 chip ID: 0x%04x\n", chip_id);

This should be a dev_dbg() message, drivers should be silent at probe
time when everything goes fine to avoid slowing down the boot process.

> +
> +	if (chip_id != IMX908_CHIP_ID) {
> +		dev_err(imx->dev, "Unexpected chip ID 0x%04x (expected 0x%04x)\n",
> +			chip_id, IMX908_CHIP_ID);
> +		return -ENXIO;
> +	}
> +
> +	/* Set to standby mode */
> +	ret = cci_write(imx->cci, IMX908_REG_STANDBY, IMX908_STANDBY_EN, NULL);
> +	if (ret)
> +		dev_err(imx->dev, "failed to enter standby state: %d\n", ret);

This error shouldn't be ignored:

		return ret;
	}

> +
> +	return 0;
> +}
> +
> +static int imx908_probe(struct i2c_client *client)
> +{
> +	struct imx908 *imx;
> +	int ret;
> +
> +	/* Allocate Memory */
> +	imx = devm_kzalloc(&client->dev, sizeof(*imx), GFP_KERNEL);
> +	if (!imx)
> +		return dev_err_probe(&client->dev, -ENOMEM,
> +				     "failed to allocate IMX908 device structure\n");

I would simply

		return -ENOMEM;

here. kzalloc() failures are logged by the allocator.

> +	imx->dev = &client->dev;
> +
> +	/* Initialize V4L2 subdevice */
> +	v4l2_i2c_subdev_init(&imx->sd, client, &imx908_subdev_ops);
> +	imx->sd.internal_ops = &imx908_internal_ops;
> +
> +	/* Register access initialization. Set 2-byte (16-bit) addresses */
> +	imx->cci = devm_cci_regmap_init_i2c(client, 16);
> +	if (IS_ERR(imx->cci))
> +		return dev_err_probe(&client->dev, PTR_ERR(imx->cci),
> +				     "CCI regmap init failed\n");
> +
> +	/* Get mandatory input clock from DT (INCK) */
> +	imx->xclk = devm_clk_get(imx->dev, "xclk");

The DT bindings don't specify a clock name, use NULL instead of "xclk".

> +	if (IS_ERR(imx->xclk))
> +		return dev_err_probe(imx->dev, PTR_ERR(imx->xclk), "xclk\n");

That's a bit short as an error message.

		return dev_err_probe(imx->dev, PTR_ERR(imx->xclk),
				     "failed to get clock\n");

> +
> +	/* Get clock frequency and check against acceptable HW values */
> +	imx->xclk_freq = clk_get_rate(imx->xclk);

imx->xclk_freq is used in imx908_get_inck_sel() only. You can drop the
field from the structure, and pass it as an argument to the function.

> +	ret = imx908_get_inck_sel(imx);
> +	if (ret)
> +		return ret;
> +
> +	/* GPIO reset acquisition */
> +	imx->reset_gpio = devm_gpiod_get_optional(imx->dev, "reset",
> +						  GPIOD_OUT_HIGH);
> +
> +	if (IS_ERR(imx->reset_gpio))
> +		return dev_err_probe(imx->dev, PTR_ERR(imx->reset_gpio),
> +				     "reset gpio\n");

Same here, "failed to get reset GPIO\n".

> +
> +	/* Link to power supplies */
> +	ret = imx908_get_regulators(imx);
> +	if (ret)
> +		return dev_err_probe(&client->dev, ret,
> +				     "regulator get failed\n");

And for consistency, "failed to get regulators\n". Same comment for the
messages below.

> +
> +	/* Parse Device Tree endpoint */
> +	ret = imx908_parse_fwnode(imx);
> +	if (ret)
> +		return dev_err_probe(&client->dev, ret,
> +				     "device tree parse failed\n");
> +
> +	/* Power on IMX908 image sensor */
> +	ret = imx908_power_on(imx);
> +	if (ret)
> +		return dev_err_probe(&client->dev, ret, "power-on failed\n");
> +
> +	/* Read IMX908 device ID */
> +	ret = imx908_identify_model(imx);
> +	if (ret) {
> +		dev_err(imx->dev, "failed to identify model: %d\n", ret);
> +		goto err_power_off;
> +	}
> +
> +	pm_runtime_set_active(imx->dev);
> +	pm_runtime_enable(imx->dev);
> +
> +	ret = imx908_init_controls(imx);
> +	if (ret)
> +		goto err_pm_disable;
> +
> +	/* Initialize V4L2 subdevice, media entity, and pad */
> +	imx->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_HAS_EVENTS;
> +	imx->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> +	imx->pad.flags = MEDIA_PAD_FL_SOURCE;
> +	ret = media_entity_pads_init(&imx->sd.entity, 1, &imx->pad);
> +	if (ret)
> +		goto err_hdl;
> +
> +	/* Use ctrl handler mutex for centrally managed subdev state */
> +	imx->sd.state_lock = imx->ctrls.handler.lock;
> +
> +	ret = v4l2_subdev_init_finalize(&imx->sd);
> +	if (ret)
> +		goto err_entity;
> +
> +	pm_runtime_set_autosuspend_delay(imx->dev, 1000);
> +	pm_runtime_use_autosuspend(imx->dev);
> +	pm_runtime_mark_last_busy(imx->dev);
> +
> +	ret = v4l2_async_register_subdev_sensor(&imx->sd);
> +	if (ret)
> +		goto err_pm_disable;
> +
> +	return 0;
> +
> +err_pm_disable:
> +	pm_runtime_disable(imx->dev);
> +	pm_runtime_set_suspended(imx->dev);
> +	v4l2_subdev_cleanup(&imx->sd);
> +err_entity:
> +	media_entity_cleanup(&imx->sd.entity);
> +err_hdl:
> +	v4l2_ctrl_handler_free(imx->sd.ctrl_handler);
> +err_power_off:
> +	imx908_power_off(imx);
> +
> +	return ret;
> +}
> +
> +static void imx908_remove(struct i2c_client *client)
> +{
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct imx908 *imx = to_imx908(sd);
> +
> +	v4l2_async_unregister_subdev(sd);
> +	v4l2_subdev_cleanup(sd);
> +	media_entity_cleanup(&sd->entity);
> +	v4l2_ctrl_handler_free(sd->ctrl_handler);
> +
> +	pm_runtime_disable(imx->dev);
> +	if (!pm_runtime_status_suspended(imx->dev))
> +		imx908_power_off(imx);
> +	pm_runtime_set_suspended(imx->dev);
> +}
> +
> +static const struct of_device_id imx908_of_ids[] = {
> +	{ .compatible = "sony,imx908" },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, imx908_of_ids);
> +
> +static struct i2c_driver imx908_i2c_driver = {
> +	.driver = {
> +		.name           = "imx908",
> +		.pm             = pm_ptr(&imx908_pm_ops),
> +		.of_match_table = imx908_of_ids,
> +	},
> +	.probe  = imx908_probe,
> +	.remove = imx908_remove,
> +};
> +module_i2c_driver(imx908_i2c_driver);
> +
> +MODULE_AUTHOR("Lachlan Michael <Lachlan.Michael@sony.com>");
> +MODULE_DESCRIPTION("Sony IMX908 Sensor Driver");
> +MODULE_LICENSE("GPL");

-- 
Regards,

Laurent Pinchart