Re: [PATCH v3 2/2] media: i2c: Add Sony IMX908 image sensor driver

[Lachlan Michael <Lachlan.Michael@sony.com>]

Dear Sakari,

On 10/1/2026 9:24 PM, Sakari Ailus wrote:
> Hi Lachlan,
> 
> Thanks for the update. A few more comments below...

Thanks for the review.
Sorry for the delay in reply as I went to Plumbers and OSS last week.

> On Fri, Aug 28, 2026 at 03:48:43PM +0900, Lachlan Michael wrote:
>> The Sony IMX908 is an 8.39 megapixel (3856x2176) CMOS image sensor
>> with a MIPI CSI-2 output interface, configurable as either 2 or 4
>> data lanes.
>>
>> Add a V4L2 sub-device driver for the sensor. The driver supports
>> RAW10 and RAW12 output formats, exposure and analogue gain controls,
>> horizontal and vertical flipping, horizontal and vertical blanking
>> controls, window cropping and test pattern generation.
>>
>> HDR modes and RAW16 output are not currently supported.
>>
>> Signed-off-by: Lachlan Michael <lachlan.michael@sony.com>
>> ---
>> Changes in v3:
>> - Correct link-frequency indexing mapping to match the sensor
>>    DATARATE_SEL values and the frequency ordering
>> - Changed the pixel_rate to 16-pixel-per-clocks based on datasheet
>>    mode values
>> - Clean up the constant names, register definitions and comments in
>>    response to review feedback.
>> - Remove various (uneeded) checks in code based on feedback
>> - Remove cached vmax/hmax and recalculated where necessary
>> - Drop pixel_rate and test_pattern pointers from struct
>> - Remove read-only controls set_ctrl switch
>> - Remove event handlers
>> - Remove uneeded delays at startup
>> - Simplify runtime_resume/suspend functions
>> - Remove the 4k recording-area in favour of larger active area
>> - Use the same constraints for VMAX for crop and all pixel mode to
>>    simplify the driver logic by removing branching
>> - Rework HMAX based on the fact that the whole line is always read
>>    even in crop mode. HMAX varies in all modes now, but not with
>>    horizontal crop.
>> - Minor edits and bugfixes
>> ---
>>   MAINTAINERS                |    1 +
>>   drivers/media/i2c/Kconfig  |   11 +
>>   drivers/media/i2c/Makefile |    1 +
>>   drivers/media/i2c/imx908.c | 1367 ++++++++++++++++++++++++++++++++++++
>>   4 files changed, 1380 insertions(+)
>>   create mode 100644 drivers/media/i2c/imx908.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index bb7adcfd4767..a17c31234ec7 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -25542,6 +25542,7 @@ SONY IMX908 SENSOR DRIVER
>>   M:	Lachlan Michael <lachlan.michael@sony.com>
>>   S:	Maintained
>>   F:	Documentation/devicetree/bindings/media/i2c/sony,imx908.yaml
>> +F:	drivers/media/i2c/imx908.c
>>   
>>   SONY MEMORYSTICK SUBSYSTEM
>>   M:	Maxim Levitsky <maximlevitsky@gmail.com>
>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>> index 5c52007f9cbe..cfa1359d8c7d 100644
>> --- a/drivers/media/i2c/Kconfig
>> +++ b/drivers/media/i2c/Kconfig
>> @@ -310,6 +310,17 @@ config VIDEO_IMX678
>>   	  To compile this driver as a module, choose M here: the
>>   	  module will be called imx678.
>>   
>> +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 be called imx908.
>> +
>>   config VIDEO_MAX9271_LIB
>>   	tristate
>>   
>> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
>> index d04bd5724552..d91ed1bc6427 100644
>> --- a/drivers/media/i2c/Makefile
>> +++ b/drivers/media/i2c/Makefile
>> @@ -63,6 +63,7 @@ obj-$(CONFIG_VIDEO_IMX412) += imx412.o
>>   obj-$(CONFIG_VIDEO_IMX415) += imx415.o
>>   obj-$(CONFIG_VIDEO_IMX678) += imx678.o
>>   obj-$(CONFIG_VIDEO_IMX471) += imx471.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..ca85a5cd058a
>> --- /dev/null
>> +++ b/drivers/media/i2c/imx908.c
>> @@ -0,0 +1,1367 @@
>> +// 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/container_of.h>
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/i2c.h>
>> +#include <linux/math.h>		/* DIV_ROUND_UP */
>> +#include <linux/math64.h>	/* DIV64_U64_ROUND_UP */
>> +#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-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_XMSTA_START	0x00
>> +#define IMX908_XMSTA_STOP	0x01
>> +#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)
>> +#define IMX908_HREVERSE_NORMAL	0x00
>> +#define IMX908_HREVERSE_INV	0x01
>> +#define IMX908_REG_VREVERSE	CCI_REG8(0x3021)
>> +#define IMX908_VREVERSE_NORMAL	0x00
>> +#define IMX908_VREVERSE_INV	0x01
>> +
>> +/* ---- 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	2250
>> +/*
>> + * VMAX restrictions, documented for window cropping mode:
>> + * VMAX >= PIX_VWIDTH + 70
>> + * VMAX >= 1206
>> + */
>> +#define IMX908_VMAX_MARGIN	70
>> +#define IMX908_VMAX_MIN		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	1100
>> +
>> +/* ---- 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)
>> +#define IMX908_LANEMODE_2LANE	0x01
>> +#define IMX908_LANEMODE_4LANE	0x03
>> +#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	4
>> +#define IMX908_CROP_ALIGN_VWIDTH	4
>> +#define IMX908_CROP_ALIGN_HSTART	4
>> +#define IMX908_CROP_ALIGN_HWIDTH	16
>> +#define IMX908_CROP_MIN_HEIGHT		1136
>> +#define IMX908_CROP_MIN_WIDTH		1040
>> +
>> +/* ---- Shutter */
>> +#define IMX908_REG_SHR0		CCI_REG24_LE(0x3050)	/* [19:0] */
>> +#define IMX908_MIN_SHR0		7
>> +
>> +/*
>> + * 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
>> +
>> +/* ---- 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 imx908_bit_depth_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
>> +
>> +/* ---- Internal image-data interface clock */
>> +#define IMX908_VTPXCK_HZ	74250000ULL
>> +
>> +/* Fixed pixel rate: 16 pixels per video timing pixel clock cycle */
>> +#define IMX908_PIX_PER_CLK	16
>> +#define IMX908_PIXEL_RATE	(IMX908_VTPXCK_HZ * IMX908_PIX_PER_CLK)
>> +
>> +/* ---- Subdev Pads */
>> +#define IMX908_SOURCE_PAD	0
>> +
>> +#define IMX908_DEFAULT_MBUS_CODE MEDIA_BUS_FMT_SRGGB10_1X10
>> +
>> +/*
>> + * IMX908 total area includes active area height plus
>> + *  4 pixels effective pixel ignored area
>> + * 10 pixels vertical direction effective OB
>> + * 10 pixels OB side ignored area
>> + */
>> +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,
>> +};
>> +
>> +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 */
>> +};
>> +
>> +/*
>> + * Link frequency indices, ordered so that the index is also the
>> + * DATARATE_SEL register value. Keep in descending frequency order.
>> + */
>> +enum {
>> +	IMX908_LINK_FREQ_1188MHZ = 0x00,
>> +	IMX908_LINK_FREQ_1039MHZ = 0x01,
>> +	IMX908_LINK_FREQ_891MHZ  = 0x02,
>> +	IMX908_LINK_FREQ_720MHZ  = 0x03,
>> +	IMX908_LINK_FREQ_594MHZ  = 0x04,
>> +	IMX908_LINK_FREQ_445MHZ  = 0x05,
>> +	IMX908_LINK_FREQ_360MHZ  = 0x06,
>> +	IMX908_LINK_FREQ_297MHZ  = 0x07,
>> +};
>> +
>> +static const s64 imx908_link_freqs[] = {
>> +	[IMX908_LINK_FREQ_1188MHZ] = 1188000000LL,
>> +	[IMX908_LINK_FREQ_1039MHZ] = 1039500000LL,
>> +	[IMX908_LINK_FREQ_891MHZ]  =  891000000LL,
>> +	[IMX908_LINK_FREQ_720MHZ]  =  720000000LL,
>> +	[IMX908_LINK_FREQ_594MHZ]  =  594000000LL,
>> +	[IMX908_LINK_FREQ_445MHZ]  =  445500000LL,
>> +	[IMX908_LINK_FREQ_360MHZ]  =  360000000LL,
>> +	[IMX908_LINK_FREQ_297MHZ]  =  297000000LL,
>> +};
>> +
>> +/* Allowed clock values in Hz */
>> +static const u32 imx908_inck_table[] = {
>> +	74250000,
>> +	37125000,
>> +	72000000,
>> +	27000000,
>> +	24000000,
>> +};
>> +
>> +struct imx908 {
>> +	struct v4l2_subdev sd;
>> +	struct media_pad pad;
>> +	struct device *dev;
>> +
>> +	struct regmap *cci;
>> +
>> +	struct clk *xclk;
>> +	struct gpio_desc *reset_gpio;
>> +	struct regulator_bulk_data supplies[ARRAY_SIZE(imx908_supply_names)];
>> +
>> +	u8 inck_sel;
>> +
>> +	u8 num_lanes;
>> +	unsigned long link_freq_bitmap;
>> +	unsigned int link_freq_idx;
>> +
>> +	struct {
>> +		struct v4l2_ctrl_handler handler;
>> +
>> +		struct v4l2_ctrl *exposure;
>> +		struct v4l2_ctrl *vblank;
>> +		struct v4l2_ctrl *hblank;
>> +	} ctrls;
>> +};
>> +
>> +static inline struct imx908 *to_imx908(struct v4l2_subdev *_sd)
>> +{
>> +	return container_of(_sd, struct imx908, sd);
>> +}
>> +
>> +/* ----------------------- Basic Helper Functions --------------------------- */
>> +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)
>> +{
>> +	u32 hmax = DIV_ROUND_UP(width + hblank, IMX908_PIX_PER_CLK);
>> +
>> +	return min_t(u32, hmax, IMX908_HMAX_MAX);
>> +}
>> +
>> +/* Horizontal cropping is digital, so the full width is always read out */
>> +static u16 imx908_calc_min_hmax(struct imx908 *imx, u8 bpp)
>> +{
>> +	u64 link_hz = imx908_link_freqs[imx->link_freq_idx];
>> +	u64 num = (u64)imx908_active_area.width * bpp * IMX908_VTPXCK_HZ;
>> +	u64 den = (u64)imx->num_lanes * link_hz * 2; /* DDR */
>> +
>> +	/*
>> +	 * den can exceed 32 bits (e.g. 4 lanes * 720 MHz * 2 = 5.76 GHz), so
>> +	 * DIV_ROUND_UP_ULL / do_div would truncate the divisor to u32. Use a
>> +	 * full 64/64 division.
>> +	 */
>> +	return DIV64_U64_ROUND_UP(num, den);
>> +}
>> +
>> +static u32 imx908_calc_min_vblank(const struct v4l2_rect *crop)
>> +{
>> +	u32 min_vmax = max_t(u32, crop->height + IMX908_VMAX_MARGIN,
>> +			 IMX908_VMAX_MIN);
> 
> Alignment.

Sorry. Too reliant on auto-tools.

>> +
>> +	return min_vmax - crop->height;
>> +}
>> +
>> +static int imx908_set_exposure_lines(struct imx908 *imx, u32 exposure_lines)
>> +{
>> +	const struct v4l2_mbus_framefmt *format;
>> +	struct v4l2_subdev_state *state;
>> +	u32 vmax, max_lines;
>> +
>> +	state = v4l2_subdev_get_locked_active_state(&imx->sd);
>> +	format = v4l2_subdev_state_get_format(state, IMX908_SOURCE_PAD);
>> +
>> +	vmax = format->height + imx->ctrls.vblank->val;
>> +	max_lines = vmax - IMX908_MIN_SHR0;
>> +
>> +	/* Guards SHR0 underflow when VBLANK+EXPOSURE are set together */
>> +	exposure_lines = clamp_t(u32, exposure_lines, 1, max_lines);
>> +
>> +	u32 shr0 = 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 u32 imx908_hmax_to_hblank(u16 hmax, u32 width)
>> +{
>> +	return hmax * IMX908_PIX_PER_CLK - width;
>> +}
>> +
>> +static int imx908_update_hblank_limits(struct imx908 *imx, u32 old_width,
>> +				       u32 width, u8 bpp)
>> +{
>> +	u16 min_hmax = imx908_calc_min_hmax(imx, bpp);
>> +	u32 max_hblank = imx908_hmax_to_hblank(IMX908_HMAX_MAX, width);
>> +	u32 min_hblank = imx908_hmax_to_hblank(min_hmax, width);
>> +	/* Re-derive the line period at the old width to preserve line time */
>> +	u16 hmax = imx908_calc_hmax(old_width, imx->ctrls.hblank->val);
>> +	u32 hblank = imx908_hmax_to_hblank(hmax, width);
>> +	int ret;
>> +
>> +	hblank = clamp_t(u32, hblank, min_hblank, max_hblank);
>> +
>> +	ret = __v4l2_ctrl_modify_range(imx->ctrls.hblank, min_hblank,
>> +				       max_hblank, IMX908_PIX_PER_CLK, hblank);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (imx->ctrls.hblank->val != hblank)
>> +		__v4l2_ctrl_s_ctrl(imx->ctrls.hblank, hblank);
> 
> __v4l2_ctrl_s_ctrl() can fail, please return the error here.

This has been removed in v4 based on previous comments.

>> +
>> +	return 0;
>> +}
>> +
>> +static int imx908_update_vblank_limits(struct imx908 *imx,
>> +				       const struct v4l2_rect *crop,
>> +				       u32 old_height)
>> +{
>> +	u32 min_vblank = imx908_calc_min_vblank(crop);
>> +	u32 max_vblank = IMX908_VMAX_MAX - crop->height;
>> +	/* Preserve frame length across height changes when possible. */
>> +	u32 vmax = old_height + imx->ctrls.vblank->val;
>> +	u32 vblank = clamp_t(u32, vmax - crop->height,
>> +			     min_vblank, max_vblank);
>> +	int ret;
>> +
>> +	ret = __v4l2_ctrl_modify_range(imx->ctrls.vblank, min_vblank,
>> +				       max_vblank, 1, vblank);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (imx->ctrls.vblank->val != vblank)
>> +		__v4l2_ctrl_s_ctrl(imx->ctrls.vblank, vblank);
> 
> Ditto.
> 
> You should omit the check btw.; this is something the control framework
> does. Same in the above function.

Fixed in v4, also thanks to comment from Jai.

>> +
>> +	return 0;
>> +}
>> +
>> +/* ------------------ 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;
>> +}
>> +
>> +static int imx908_update_framing_limits(struct imx908 *imx,
>> +					struct v4l2_subdev_state *state,
>> +					u32 old_width,
>> +					u32 old_height)
>> +{
>> +	const struct v4l2_mbus_framefmt *fmt;
>> +	const struct v4l2_rect *crop;
>> +	int ret;
>> +
>> +	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);
>> +
>> +	ret = imx908_update_hblank_limits(imx, old_width, fmt->width, bpp);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = imx908_update_vblank_limits(imx, crop, old_height);
>> +	if (ret)
>> +		return ret;
>> +
>> +	u32 vmax = fmt->height + clamp_t(u32, imx->ctrls.vblank->val,
>> +					 imx908_calc_min_vblank(crop),
>> +					 IMX908_VMAX_MAX - fmt->height);
>> +
>> +	return __v4l2_ctrl_modify_range(imx->ctrls.exposure,
>> +					IMX908_EXPOSURE_MIN,
>> +					vmax - IMX908_MIN_SHR0,
>> +					IMX908_EXPOSURE_STEP,
>> +					imx->ctrls.exposure->default_value);
>> +}
>> +
>> +/* ----------------------- HW Programming ---------------------- */
>> +static int imx908_set_mode(struct imx908 *imx,
>> +			   const struct v4l2_mbus_framefmt *fmt)
>> +{
>> +	u8 adbit, mdbit, value;
> 
> As value is used for a set of registers, I'd call it accordingly, e.g.
> bit_depth_value.

Ok. In v4 there is also another register that I added (based on the 
latest setting file) which also changes based on bit depth. I call it 
reg359c_value since it is register 0x359c, but if bit_depth_value2 or 
similar is better let me know.

>> +	u16 blklevel;
>> +	int ret = 0;
>> +
>> +	switch (fmt->code) {
>> +	case MEDIA_BUS_FMT_SRGGB10_1X10:
>> +		adbit = IMX908_ADBIT_10BIT;
>> +		mdbit = IMX908_MDBIT_RAW10;
>> +		blklevel = 50; /* datasheet recommended value for 10-bit */
>> +		value = 0x0c;  /* register map value for 10-bit */
>> +		break;
>> +	case MEDIA_BUS_FMT_SRGGB12_1X12:
>> +	default:
>> +		adbit = IMX908_ADBIT_12BIT;
>> +		mdbit = IMX908_MDBIT_RAW12;
>> +		blklevel = 200; /* datasheet recommended value for 12-bit */
>> +		value = 0x05;   /* register map value for 12-bit */
>> +		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);
>> +
>> +	for (unsigned int i = 0; i < ARRAY_SIZE(imx908_bit_depth_regs); ++i)
>> +		cci_write(imx->cci, imx908_bit_depth_regs[i], value, &ret);
>> +
>> +	cci_write(imx->cci, IMX908_REG_INCK_SEL, imx->inck_sel, &ret);
>> +	cci_write(imx->cci, IMX908_REG_DATARATE_SEL, imx->link_freq_idx, &ret);
>> +	cci_write(imx->cci, IMX908_REG_LANEMODE, imx->num_lanes == 2 ?
>> +		  IMX908_LANEMODE_2LANE : IMX908_LANEMODE_4LANE, &ret);
>> +	cci_write(imx->cci, IMX908_REG_BLKLEVEL, blklevel, &ret);
>> +
>> +	if (ret)
>> +		dev_err(imx->dev, " register write failed: %d\n", ret);
>> +
>> +	return ret;
>> +}
>> +
>> +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);
>> +
>> +	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_mbus_framefmt *format;
>> +	const struct v4l2_rect *crop;
>> +	int ret = 0;
>> +
>> +	crop = v4l2_subdev_state_get_crop(sd_state, IMX908_SOURCE_PAD);
>> +	format = v4l2_subdev_state_get_format(sd_state, IMX908_SOURCE_PAD);
>> +
>> +	cci_multi_reg_write(imx->cci, imx908_common_regs,
>> +			    ARRAY_SIZE(imx908_common_regs), &ret);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = imx908_set_mode(imx, format);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = imx908_program_window(imx, crop);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = __v4l2_ctrl_handler_setup(imx->sd.ctrl_handler);
>> +	if (ret)
>> +		return ret;
>> +
>> +	cci_write(imx->cci, IMX908_REG_STANDBY, IMX908_STANDBY_CANCEL, &ret);
>> +	fsleep(24 * USEC_PER_MSEC); /* >=24 ms stabilization after standby cancel */
>> +
>> +	cci_write(imx->cci, IMX908_REG_XMSTA, IMX908_XMSTA_START, &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_XMSTA_STOP, &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);
>> +	const struct v4l2_mbus_framefmt *format;
>> +	struct v4l2_subdev_state *state;
>> +	int ret = 0;
>> +
>> +	state = v4l2_subdev_get_locked_active_state(&imx->sd);
>> +	format = v4l2_subdev_state_get_format(state, IMX908_SOURCE_PAD);
>> +
>> +	/* Update exposure control limits even if the sensor is not streaming */
>> +	if (ctrl->id == 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_VMAX_MAX - format->height;
>> +		u32 vblank = clamp_t(u32, ctrl->val, min_vblank, max_vblank);
>> +
>> +		u32 vmax = format->height + vblank;
>> +		u32 max_exposure = vmax - IMX908_MIN_SHR0;
>> +		u32 current_exposure = clamp_t(u32, imx->ctrls.exposure->cur.val,
>> +					IMX908_EXPOSURE_MIN, max_exposure);
>> +
>> +		ret = __v4l2_ctrl_modify_range(imx->ctrls.exposure,
>> +					       IMX908_EXPOSURE_MIN,
>> +					       max_exposure,
>> +					       IMX908_EXPOSURE_STEP,
>> +					       current_exposure);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	/* Hardware writes only when powered; cached ctrls applied on resume */
>> +	if (!pm_runtime_get_if_active(imx->dev))
>> +		return 0;
>> +
>> +	switch (ctrl->id) {
>> +	case V4L2_CID_EXPOSURE:
>> +		ret = imx908_set_exposure_lines(imx, ctrl->val);
>> +		break;
>> +
>> +	case V4L2_CID_ANALOGUE_GAIN:
>> +		cci_write(imx->cci, IMX908_REG_GAIN, ctrl->val, &ret);
>> +		break;
>> +
>> +	case V4L2_CID_VBLANK: {
>> +		u32 vmax = format->height + ctrl->val;
>> +
>> +		ret = cci_write(imx->cci, IMX908_REG_VMAX, vmax, NULL);
>> +		/* SHR0 derived from VMAX, re-apply exposure after changes */
>> +		if (!ret)
>> +			ret = imx908_set_exposure_lines(imx,
>> +							imx->ctrls.exposure->val);
>> +		break;
>> +	}
>> +
>> +	case V4L2_CID_HBLANK: {
>> +		u16 hmax = imx908_calc_hmax(format->width, ctrl->val);
>> +
>> +		cci_write(imx->cci, IMX908_REG_HMAX, hmax, &ret);
>> +		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 ? IMX908_HREVERSE_INV
>> +			  : IMX908_HREVERSE_NORMAL, &ret);
>> +		break;
>> +
>> +	case V4L2_CID_VFLIP:
>> +		cci_write(imx->cci, IMX908_REG_VREVERSE,
>> +			  ctrl->val ? IMX908_VREVERSE_INV
>> +			  : IMX908_VREVERSE_NORMAL, &ret);
>> +		break;
>> +
>> +	default:
>> +		dev_warn(imx->dev,
>> +			 "ctrl(id:0x%x,val:0x%x) is not handled\n",
>> +			 ctrl->id, ctrl->val);
>> +		break;
>> +	}
>> +
>> +	pm_runtime_put(imx->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;
> 
> Maybe a newline here?

Ok.

>> +	code->code = imx908_mbus_codes[code->index];
> 
> And here.

Ok.

>> +	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)
>> +{
>> +	struct imx908 *imx = to_imx908(sd);
>> +	const struct v4l2_rect *crop;
>> +
>> +	if (fse->index > 0)
>> +		return -EINVAL;
>> +
>> +	if (!imx908_mbus_code_supported(imx, fse->code))
>> +		return -EINVAL;
>> +
>> +	crop = v4l2_subdev_state_get_crop(sd_state, IMX908_SOURCE_PAD);
>> +
>> +	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;
>> +
>> +	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;
>> +
>> +	/* Limits track the real controls only for the ACTIVE state, not TRY */
>> +	if (fmt->which == V4L2_SUBDEV_FORMAT_ACTIVE) {
>> +		/* set_pad_format() never changes width, so old == new here */
>> +		u32 old_width = format->width;
>> +		u32 old_height = format->height;
>> +		int ret = imx908_update_framing_limits(imx, sd_state,
>> +					       old_width, old_height);
>> +
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	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)
> 
> We don't really have cropping behaviour documented before the common raw
> sensor model. I'd just postpone this until we have the common raw sensor
> model support
> <URL:https://git.linuxtv.org/sailus/media_tree.git/log/?h=metadata> merged.

Understood. We'll drop in v4.
We'll fully support with additional patches for this at the appropriate 
time.

>> +{
>> +	struct imx908 *imx = to_imx908(sd);
>> +	struct v4l2_mbus_framefmt *format;
>> +	struct v4l2_rect *r = &sel->r;
>> +	struct v4l2_rect *crop;
>> +
>> +	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);
>> +
>> +	u32 old_width = crop->width;
>> +	u32 old_height = crop->height;
>> +
>> +	*crop = *r;
>> +
>> +	/* IMX908 has no binning, so the output size matches the crop 1:1 */
>> +	format->width  = crop->width;
>> +	format->height = crop->height;
>> +
>> +	if (sel->which == V4L2_SUBDEV_FORMAT_ACTIVE) {
>> +		int ret = imx908_update_framing_limits(imx, sd_state,
>> +					       old_width, old_height);
>> +
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	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_active_area;
>> +		return 0;
>> +
>> +	case V4L2_SEL_TGT_CROP_BOUNDS:
> 
> You can combine with with the above case.

Fixed in v4.

>> +		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, sd_state);
>> +	if (ret) {
>> +		pm_runtime_put_autosuspend(imx->dev);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +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);
> 
> imx908_stop_streaming() is used in a single location only. I think you
> should move the code here. Same for imx908_enable_streams() and
> imx906_start_streaming(), too.

In v4 I removed imx908_stop_streaming() and imx908_start_streaming() by 
merging them into imx908_disable_streams() and imx908_enable_streams().

>> +
>> +	pm_runtime_put_autosuspend(imx->dev);
>> +
>> +	return ret;
>> +}
>> +
>> +static int imx908_init_state(struct v4l2_subdev *sd,
>> +			     struct v4l2_subdev_state *sd_state)
>> +{
>> +	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,
>> +		},
>> +	};
>> +
>> +	imx908_set_selection(sd, sd_state, &sel);
>> +	imx908_set_pad_format(sd, sd_state, &fmt);
>> +
>> +	return 0;
>> +}
>> +
>> +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 = {
>> +	.video = &imx908_video_ops,
>> +	.pad   = &imx908_pad_ops,
>> +};
>> +
>> +/* ----------------------- Power management ---------------------- */
>> +static int imx908_power_on(struct device *dev)
>> +{
>> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>> +	struct imx908 *imx = to_imx908(sd);
>> +	int ret;
>> +
>> +	ret = regulator_bulk_enable(ARRAY_SIZE(imx908_supply_names),
>> +				    imx->supplies);
>> +	if (ret) {
>> +		dev_err(imx->dev, "failed to enable regulators\n");
>> +		return ret;
>> +	}
>> +	/* XCLR already asserted by GPIOD_OUT_HIGH */
>> +	udelay(1); /* >= 500ns T_low */
>> +	gpiod_set_value_cansleep(imx->reset_gpio, 0); /* Sensor start */
>> +
>> +	ret = clk_prepare_enable(imx->xclk);
>> +	if (ret) {
>> +		dev_err(imx->dev, "failed to enable xclk: %d\n", ret);
>> +		goto err_reset;
>> +	}
>> +
>> +	fsleep(20); /* T_1 >= 20us before first SDA/SCL */
>> +
>> +	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 device *dev)
>> +{
>> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>> +	struct imx908 *imx = to_imx908(sd);
>> +
>> +	clk_disable_unprepare(imx->xclk);
>> +	gpiod_set_value_cansleep(imx->reset_gpio, 1);
>> +	regulator_bulk_disable(ARRAY_SIZE(imx908_supply_names), imx->supplies);
>> +}
>> +
>> +static int imx908_runtime_resume(struct device *dev)
>> +{
>> +	return imx908_power_on(dev);
> 
> Please move the code from imx908_power_on() here; similarly for
> imx908_runtime_suspend() and imx908_power_off().

Ok. In v4 I removed the imx908_power_on() and imx908_power_off and 
merged them into imx908_runtime_resume() and imx908_runtime_suspend().
>> +}
>> +
>> +static int imx908_runtime_suspend(struct device *dev)
>> +{
>> +	imx908_power_off(dev);
>> +	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, u32 xclk_freq)
>> +{
>> +	for (unsigned int i = 0; i < ARRAY_SIZE(imx908_inck_table); i++) {
>> +		if (imx908_inck_table[i] == xclk_freq) {
>> +			imx->inck_sel = i;
>> +			return 0;
>> +		}
>> +	}
>> +
>> +	return dev_err_probe(imx->dev, -EINVAL, "unsupported xclk %u Hz\n",
>> +			     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 v4l2_fwnode_endpoint bus_cfg = {
>> +		.bus_type = V4L2_MBUS_CSI2_DPHY
>> +	};
>> +	struct fwnode_handle *ep;
>> +	int ret = 0;
>> +
>> +	ep = fwnode_graph_get_next_endpoint(dev_fwnode(imx->dev), NULL);
>> +
>> +	/* Only data-lanes and link-frequencies are used from the endpoint */
> 
> This is trivially visible below, please drop the comment.

Ok.

>> +	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)
>> +		goto out_free;
>> +
>> +	imx->link_freq_idx = __ffs(imx->link_freq_bitmap);
>> +	dev_dbg(imx->dev, "using %u lanes at link freq %llu Hz\n",
>> +		imx->num_lanes, imx908_link_freqs[imx->link_freq_idx]);
> 
> This information is already printed by v4l2-fwnode framework, please drop.

Ok.

>> +
>> +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_fwnode_device_properties props;
>> +	struct v4l2_ctrl *ctrl;
>> +	int ret;
>> +
>> +	/* Read rotation and orientation properties from the firmware node */
>> +	ret = v4l2_fwnode_device_parse(imx->dev, &props);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = v4l2_ctrl_handler_init(hdl, 11);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* PIXEL_RATE is always read-only, so it needs no s_ctrl() handling */
>> +	v4l2_ctrl_new_std(hdl, NULL, V4L2_CID_PIXEL_RATE,
>> +			  IMX908_PIXEL_RATE, IMX908_PIXEL_RATE, 1,
>> +			  IMX908_PIXEL_RATE);
>> +
>> +	/* LINK_FREQ is informational only and has no s_ctrl() handling */
>> +	ctrl = v4l2_ctrl_new_int_menu(hdl, NULL, V4L2_CID_LINK_FREQ,
>> +				      ARRAY_SIZE(imx908_link_freqs) - 1,
>> +				      imx->link_freq_idx, imx908_link_freqs);
>> +	if (ctrl)
>> +		ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
>> +
>> +	u32 min_vblank = imx908_calc_min_vblank(&imx908_active_area);
>> +	u32 max_vblank = IMX908_VMAX_MAX - imx908_active_area.height;
>> +	/* Default to the datasheet 30 fps operating point */
>> +	u32 def_vblank = IMX908_VMAX_DEFAULT - imx908_active_area.height;
>> +
>> +	imx->ctrls.vblank = v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops,
>> +					      V4L2_CID_VBLANK, min_vblank,
>> +					      max_vblank, 1, def_vblank);
>> +
>> +	u8 bpp = imx908_bits_per_pixel(IMX908_DEFAULT_MBUS_CODE);
>> +	u16 min_hmax = imx908_calc_min_hmax(imx, bpp);
>> +	u32 min_hblank = imx908_hmax_to_hblank(min_hmax,
>> +					       imx908_active_area.width);
>> +	u32 max_hblank = imx908_hmax_to_hblank(IMX908_HMAX_MAX,
>> +					       imx908_active_area.width);
>> +	u32 hblank = imx908_hmax_to_hblank(IMX908_HMAX_DEFAULT,
>> +					   imx908_active_area.width);
>> +
>> +	/* Default HMAX can be infeasible at low link freqs; clamp into range */
>> +	hblank = clamp_t(u32, hblank, min_hblank, max_hblank);
>> +
>> +	imx->ctrls.hblank = v4l2_ctrl_new_std(hdl, &imx908_ctrl_ops,
>> +					      V4L2_CID_HBLANK, min_hblank,
>> +					      max_hblank, IMX908_PIX_PER_CLK,
>> +					      hblank);
>> +	u32 max_exp = IMX908_VMAX_DEFAULT - IMX908_MIN_SHR0;
>> +
>> +	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) */
>> +	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);
>> +
>> +	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);
>> +
>> +	v4l2_ctrl_new_fwnode_properties(hdl, &imx908_ctrl_ops, &props);
>> +	if (hdl->error) {
>> +		ret = hdl->error;
> 
> No need to assign ret, just return hdl->error below.

Ok.

>> +		goto err_free;
>> +	}
>> +
>> +	imx->sd.ctrl_handler = hdl;
>> +
>> +	return 0;
>> +
>> +err_free:
>> +	v4l2_ctrl_handler_free(hdl);
>> +	return ret;
>> +}
>> +
>> +static int imx908_identify_model(struct imx908 *imx)
>> +{
>> +	u16 chip_id;
>> +	u64 val;
>> +	int ret;
>> +
>> +	/*
>> +	 * 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;
>> +
>> +	fsleep(24 * USEC_PER_MSEC); /* >=24 ms stabilization after standby cancel */
>> +
>> +	ret = cci_read(imx->cci, IMX908_REG_TYPE_ID, &val, NULL);
>> +	if (ret)
>> +		return ret;
>> +
>> +	chip_id = val;
>> +	dev_dbg(imx->dev, "IMX908 chip ID: 0x%04x\n", chip_id);
>> +
>> +	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 to save power */
>> +	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);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int imx908_probe(struct i2c_client *client)
>> +{
>> +	struct imx908 *imx;
>> +	int ret;
>> +
>> +	imx = devm_kzalloc(&client->dev, sizeof(*imx), GFP_KERNEL);
>> +	if (!imx)
>> +		return -ENOMEM;
>> +	imx->dev = &client->dev;
>> +
>> +	v4l2_i2c_subdev_init(&imx->sd, client, &imx908_subdev_ops);
>> +	imx->sd.internal_ops = &imx908_internal_ops;
>> +
>> +	imx->cci = devm_cci_regmap_init_i2c(client, 16);
>> +	if (IS_ERR(imx->cci))
>> +		return dev_err_probe(imx->dev, PTR_ERR(imx->cci),
>> +				     "CCI regmap init failed\n");
>> +
>> +	imx->xclk = devm_v4l2_sensor_clk_get(imx->dev, NULL);
>> +	if (IS_ERR(imx->xclk))
>> +		return dev_err_probe(imx->dev, PTR_ERR(imx->xclk),
>> +				     "failed to get clock\n");
>> +
>> +	ret = imx908_get_inck_sel(imx, clk_get_rate(imx->xclk));
>> +	if (ret)
>> +		return ret;
>> +
>> +	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),
>> +				     "failed to get reset gpio\n");
>> +
>> +	ret = imx908_get_regulators(imx);
>> +	if (ret)
>> +		return dev_err_probe(imx->dev, ret, "failed to get regulators\n");
>> +
>> +	ret = imx908_parse_fwnode(imx);
>> +	if (ret)
>> +		return dev_err_probe(imx->dev, ret, "device tree parse failed\n");
>> +
>> +	ret = imx908_power_on(imx->dev);
>> +	if (ret)
>> +		return dev_err_probe(imx->dev, ret, "power-on failed\n");
>> +
>> +	ret = imx908_identify_model(imx);
>> +	if (ret) {
>> +		dev_err(imx->dev, "failed to identify model: %d\n", ret);
>> +		goto err_power_off;
>> +	}
>> +
>> +	/* Device is powered; keep it resumed across registration, release at end */
>> +	pm_runtime_set_active(imx->dev);
>> +	pm_runtime_get_noresume(imx->dev);
>> +	ret = devm_pm_runtime_enable(imx->dev);
> 
> What will happen on error here? PM runtime will be disabled after probe()
> exits on error, but you'd need to set the state to suspended after that.
> I'm not sure you can correctly use this as things stand currently. This
> also conflicts currently with remove() below disabling Runtime PM
> explicitly.

In v4 I rewrote this with hints from IMX678.

>> +	if (ret)
>> +		goto err_pm_put;
>> +
>> +	pm_runtime_set_autosuspend_delay(imx->dev, 1000);
>> +	pm_runtime_use_autosuspend(imx->dev);
> 
> I'd move this after registering the sensor sub-device.

Ok, changed in v4.

>> +	ret = imx908_init_controls(imx);
>> +	if (ret)
>> +		goto err_pm_put;
>> +
>> +	imx->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
>> +	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;
>> +
>> +	/* Share the ctrl handler lock so s_ctrl can access the locked state */
>> +	imx->sd.state_lock = imx->ctrls.handler.lock;
>> +
>> +	ret = v4l2_subdev_init_finalize(&imx->sd);
>> +	if (ret)
>> +		goto err_entity;
>> +
>> +	ret = v4l2_async_register_subdev_sensor(&imx->sd);
>> +	if (ret)
>> +		goto err_subdev;
>> +
>> +	/* Balance get_noresume; allow the sensor to suspend after probe */
>> +	pm_runtime_put_autosuspend(imx->dev);
> 
> Please use pm_runtime_idle() here instead as I requested in review of v2.

Done in v4.

>> +
>> +	return 0;
>> +
>> +err_subdev:
>> +	v4l2_subdev_cleanup(&imx->sd);
>> +
>> +err_entity:
>> +	media_entity_cleanup(&imx->sd.entity);
>> +
>> +err_hdl:
>> +	v4l2_ctrl_handler_free(imx->sd.ctrl_handler);
>> +
>> +err_pm_put:
>> +	pm_runtime_put_noidle(imx->dev);
>> +
>> +err_power_off:
>> +	imx908_power_off(imx->dev);
>> +
>> +	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_dont_use_autosuspend();
> 
> ?

Autosuspend is enabled in probe() with pm_runtime_use_autosuspend(), so 
I call pm_runtime_dont_use_autosuspend() during remove before disabling 
runtime PM.


>> +	pm_runtime_disable(imx->dev);
>> +	if (!pm_runtime_status_suspended(imx->dev))
>> +		imx908_power_off(imx->dev);
>> +	pm_runtime_set_suspended(imx->dev);
> 
> This needs to be conditional to status being suspended, too.

Ok, fixed in v4.

>> +}
>> +
>> +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");
>