Re: [PATCH 2/2] media: Add imx334 camera sensor driver

[Andrey Konovalov <andrey.konovalov@linaro.org>]

Hi,

Martina, thanks for the patch

Jacopo, thanks for the review

One minor comment below..

On 23.11.2020 14:10, Jacopo Mondi wrote:
> Hi Martina,
>     thanks, a few comments below quickly skimming through the driver
> 
> On Fri, Nov 20, 2020 at 02:28:03PM +0000, Martina Krasteva wrote:
>> From: Martina Krasteva <martinax.krasteva@intel.com>
>>
>> Add a v4l2 sub-device driver for the Sony imx334 image sensor.
>> This is a camera sensor using the i2c bus for control and the
>> csi-2 bus for data.
>>
>> The following features are supported:
>> - manual exposure and analog gain control support
>> - vblank/hblank/pixel rate control support
>> - supported resolution:
>>      - 3840x2160 @ 60fps
>> - supported bayer order output:
>>      - SRGGB12
>>
>> Signed-off-by: Martina Krasteva <martinax.krasteva@intel.com>
>> Reviewed-by: Gjorgji Rosikopulos <gjorgjix.rosikopulos@intel.com>
>> Acked-by: Daniele Alessandrelli <daniele.alessandrelli@intel.com>
>> ---
>>   MAINTAINERS                |    1 +
>>   drivers/media/i2c/Kconfig  |   14 +
>>   drivers/media/i2c/Makefile |    1 +
>>   drivers/media/i2c/imx334.c | 1089 ++++++++++++++++++++++++++++++++++++++++++++
>>   4 files changed, 1105 insertions(+)
>>   create mode 100644 drivers/media/i2c/imx334.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 6cfce99be4bb..24438c53861b 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -16326,6 +16326,7 @@ L:	linux-media@vger.kernel.org
>>   S:	Maintained
>>   T:	git git://linuxtv.org/media_tree.git
>>   F:	Documentation/devicetree/bindings/media/i2c/sony,imx334.yaml
>> +F:	drivers/media/i2c/imx334.c
>>
>>   SONY IMX355 SENSOR DRIVER
>>   M:	Tianshu Qiu <tian.shu.qiu@intel.com>
>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>> index 878f66ef2719..f67b7e05b796 100644
>> --- a/drivers/media/i2c/Kconfig
>> +++ b/drivers/media/i2c/Kconfig
>> @@ -813,6 +813,20 @@ config VIDEO_IMX319
>>   	  To compile this driver as a module, choose M here: the
>>   	  module will be called imx319.
>>
>> +config VIDEO_IMX334
>> +	tristate "Sony IMX334 sensor support"
>> +	depends on OF_GPIO
>> +	depends on I2C && VIDEO_V4L2
>> +	select VIDEO_V4L2_SUBDEV_API
>> +	select MEDIA_CONTROLLER
>> +	select V4L2_FWNODE
>> +	help
>> +	  This is a Video4Linux2 sensor driver for the Sony
>> +	  IMX334 camera.
>> +
>> +	  To compile this driver as a module, choose M here: the
>> +	  module will be called imx334.
>> +
>>   config VIDEO_IMX355
>>   	tristate "Sony IMX355 sensor support"
>>   	depends on I2C && VIDEO_V4L2
>> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
>> index f0a77473979d..aeaeaab3783c 100644
>> --- a/drivers/media/i2c/Makefile
>> +++ b/drivers/media/i2c/Makefile
>> @@ -118,6 +118,7 @@ obj-$(CONFIG_VIDEO_IMX258)	+= imx258.o
>>   obj-$(CONFIG_VIDEO_IMX274)	+= imx274.o
>>   obj-$(CONFIG_VIDEO_IMX290)	+= imx290.o
>>   obj-$(CONFIG_VIDEO_IMX319)	+= imx319.o
>> +obj-$(CONFIG_VIDEO_IMX334)	+= imx334.o
>>   obj-$(CONFIG_VIDEO_IMX355)	+= imx355.o
>>   obj-$(CONFIG_VIDEO_MAX9286)	+= max9286.o
>>   rdacm20-camera_module-objs	:= rdacm20.o max9271.o
>> diff --git a/drivers/media/i2c/imx334.c b/drivers/media/i2c/imx334.c
>> new file mode 100644
>> index 000000000000..8fd2c1c934fd
>> --- /dev/null
>> +++ b/drivers/media/i2c/imx334.c
>> @@ -0,0 +1,1089 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Sony imx334 sensor driver
>> + *
>> + * Copyright (C) 2019-2020 Intel Corporation
>> + */
>> +#include <asm/unaligned.h>
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/i2c.h>
>> +#include <linux/module.h>
>> +#include <linux/pm_runtime.h>
>> +#include <linux/platform_device.h>
> 
> Do you need this include ?
> 
> I think you also need:
> 
> #include <linux/gpio/consumer.h>
> #include <linux/of.h>
> 
>> +
>> +#include <media/v4l2-ctrls.h>
>> +#include <media/v4l2-device.h>
> 
> I would replace v4l2-device.h with v4l2-subdev.h being this
> effectively a subdev driver
> 
>> +#include <media/v4l2-fwnode.h>
> 
> You only use v4l2_async_register_subdev_sensor_common() from fwnde.h
> If you think you can replace it with v4l2_async_register_subdev() (see
> below comment) this should be changed in v4l2-async.h
> 
>> +
>> +#define IMX334_DRV_NAME		"imx334"
> 
> Used in a single place, not sure it's worth it.
> 
>> +
>> +/* Streaming Mode */
>> +#define IMX334_REG_MODE_SELECT	0x3000
>> +#define IMX334_MODE_STANDBY	0x01
>> +#define IMX334_MODE_STREAMING	0x00
>> +
>> +/* Lines per frame */
>> +#define IMX334_REG_LPFR		0x3030
>> +
>> +#define IMX334_LPFR_MIN		0x08ca
>> +#define IMX334_LPFR_MAX		0x20f58
>> +
>> +/* Chip ID */
>> +#define IMX334_REG_ID		0x3044
>> +#define IMX334_ID		0x1e00
>> +
>> +/* Exposure control */
>> +#define IMX334_REG_SHUTTER	0x3058
>> +#define IMX334_EXPOSURE_MIN	1
>> +#define IMX334_EXPOSURE_OFFSET	5
>> +#define IMX334_EXPOSURE_STEP	1
>> +#define IMX334_EXPOSURE_DEFAULT	0x0648
>> +
>> +/* Analog gain control */
>> +#define IMX334_REG_AGAIN	0x30e8
>> +#define IMX334_AGAIN_MIN	0
>> +#define IMX334_AGAIN_MAX	240
>> +#define IMX334_AGAIN_STEP	1
>> +#define IMX334_AGAIN_DEFAULT	0
>> +
>> +/* Group hold register */
>> +#define IMX334_REG_HOLD		0x3001
>> +
>> +/* Input clock rate */
>> +#define IMX334_INCLK_RATE	24000000
>> +
>> +#define IMX334_REG_MIN		0x00
>> +#define IMX334_REG_MAX		0xfffff
>> +
>> +/**
>> + * struct imx334_reg - imx334 sensor register
>> + * @address: Register address
>> + * @val: Register value
>> + */
>> +struct imx334_reg {
>> +	u16 address;
>> +	u8 val;
>> +};
>> +
>> +/**
>> + * struct imx334_reg_list - imx334 sensor register list
>> + * @num_of_regs: Number of registers in the list
>> + * @regs: Pointer to register list
>> + */
>> +struct imx334_reg_list {
>> +	u32 num_of_regs;
>> +	const struct imx334_reg *regs;
>> +};
>> +
>> +/**
>> + * struct imx334_mode - imx334 sensor mode structure
>> + * @width: Frame width
>> + * @height: Frame height
>> + * @code: Format code
>> + * @ppln: Pixels per line
>> + * @lpfr: Lines per frame
>> + * @pclk: Sensor pixel clock
>> + * @reg_list: Register list for sensor mode
>> + */
>> +struct imx334_mode {
>> +	u32 width;
>> +	u32 height;
>> +	u32 code;
>> +	u32 ppln;
>> +	u32 lpfr;
>> +	u64 pclk;
>> +	struct imx334_reg_list reg_list;
>> +};
>> +
>> +/**
>> + * struct imx334 - imx334 sensor device structure
>> + * @dev: Pointer to generic device
>> + * @client: Pointer to i2c client
>> + * @sd: V4L2 sub-device
>> + * @pad: Media pad. Only one pad supported
>> + * @reset_gpio: Sensor reset gpio
>> + * @inclk: Sensor input clock
>> + * @ctrl_handler: V4L2 control handler
>> + * @pclk_ctrl: Pointer to pixel clock control
>> + * @hblank_ctrl: Pointer to horizontal blanking control
>> + * @vblank_ctrl: Pointer to vertical blanking control
>> + * @exp_ctrl: Pointer to exposure control
>> + * @again_ctrl: Pointer to analog gain control
>> + * @exp1_ctrl: Pointer to short exposure control
>> + * @again1_ctrl: Pointer to short analog gain control
>> + * @exp2_ctrl: Pointer to very short exposure control
>> + * @again2_ctrl: Pointer to very short analog gain control
>> + * @lpfr: Lines per frame for long exposure frame
>> + * @cur_mode: Pointer to current selected sensor mode
>> + * @mutex: Mutex for serializing sensor controls
>> + * @streaming: Flag indicating streaming state
>> + */
>> +struct imx334 {
>> +	struct device *dev;
>> +	struct i2c_client *client;
>> +	struct v4l2_subdev sd;
>> +	struct media_pad pad;
>> +	struct gpio_desc *reset_gpio;
>> +	struct clk *inclk;
>> +	struct v4l2_ctrl_handler ctrl_handler;
>> +	struct v4l2_ctrl *pclk_ctrl;
>> +	struct v4l2_ctrl *hblank_ctrl;
>> +	struct v4l2_ctrl *vblank_ctrl;
>> +	struct {
>> +		struct v4l2_ctrl *exp_ctrl;
>> +		struct v4l2_ctrl *again_ctrl;
>> +	};
>> +	u32 lpfr;
> 
> Can't you get lpfr from the current mode you have a pointer to here
> below ?
> 
>> +	const struct imx334_mode *cur_mode;
>> +	struct mutex mutex;
> 
> Checkpatch wants this mutex commented, but you have documentation so I
> think it's fine
> 
>> +	bool streaming;
>> +};
>> +
>> +/* Sensor mode registers */
>> +static const struct imx334_reg mode_3840x2160_regs[] = {
>> +	{0x3000, 0x01},
>> +	{0x3002, 0x00},
>> +	{0x3018, 0x04},
>> +	{0x37b0, 0x36},
>> +	{0x304c, 0x00},
>> +	{0x300c, 0x3b},
>> +	{0x300d, 0x2a},
>> +	{0x3034, 0x26},
>> +	{0x3035, 0x02},
>> +	{0x314c, 0x29},
>> +	{0x314d, 0x01},
>> +	{0x315a, 0x02},
>> +	{0x3168, 0xa0},
>> +	{0x316a, 0x7e},
>> +	{0x3288, 0x21},
>> +	{0x328a, 0x02},
>> +	{0x302c, 0x3c},
>> +	{0x302e, 0x00},
>> +	{0x302f, 0x0f},
>> +	{0x3076, 0x70},
>> +	{0x3077, 0x08},
>> +	{0x3090, 0x70},
>> +	{0x3091, 0x08},
>> +	{0x30d8, 0x20},
>> +	{0x30d9, 0x12},
>> +	{0x3308, 0x70},
>> +	{0x3309, 0x08},
>> +	{0x3414, 0x05},
>> +	{0x3416, 0x18},
>> +	{0x35ac, 0x0e},
>> +	{0x3648, 0x01},
>> +	{0x364a, 0x04},
>> +	{0x364c, 0x04},
>> +	{0x3678, 0x01},
>> +	{0x367c, 0x31},
>> +	{0x367e, 0x31},
>> +	{0x3708, 0x02},
>> +	{0x3714, 0x01},
>> +	{0x3715, 0x02},
>> +	{0x3716, 0x02},
>> +	{0x3717, 0x02},
>> +	{0x371c, 0x3d},
>> +	{0x371d, 0x3f},
>> +	{0x372c, 0x00},
>> +	{0x372d, 0x00},
>> +	{0x372e, 0x46},
>> +	{0x372f, 0x00},
>> +	{0x3730, 0x89},
>> +	{0x3731, 0x00},
>> +	{0x3732, 0x08},
>> +	{0x3733, 0x01},
>> +	{0x3734, 0xfe},
>> +	{0x3735, 0x05},
>> +	{0x375d, 0x00},
>> +	{0x375e, 0x00},
>> +	{0x375f, 0x61},
>> +	{0x3760, 0x06},
>> +	{0x3768, 0x1b},
>> +	{0x3769, 0x1b},
>> +	{0x376a, 0x1a},
>> +	{0x376b, 0x19},
>> +	{0x376c, 0x18},
>> +	{0x376d, 0x14},
>> +	{0x376e, 0x0f},
>> +	{0x3776, 0x00},
>> +	{0x3777, 0x00},
>> +	{0x3778, 0x46},
>> +	{0x3779, 0x00},
>> +	{0x377a, 0x08},
>> +	{0x377b, 0x01},
>> +	{0x377c, 0x45},
>> +	{0x377d, 0x01},
>> +	{0x377e, 0x23},
>> +	{0x377f, 0x02},
>> +	{0x3780, 0xd9},
>> +	{0x3781, 0x03},
>> +	{0x3782, 0xf5},
>> +	{0x3783, 0x06},
>> +	{0x3784, 0xa5},
>> +	{0x3788, 0x0f},
>> +	{0x378a, 0xd9},
>> +	{0x378b, 0x03},
>> +	{0x378c, 0xeb},
>> +	{0x378d, 0x05},
>> +	{0x378e, 0x87},
>> +	{0x378f, 0x06},
>> +	{0x3790, 0xf5},
>> +	{0x3792, 0x43},
>> +	{0x3794, 0x7a},
>> +	{0x3796, 0xa1},
>> +	{0x3e04, 0x0e},
>> +	{0x3a00, 0x01},
>> +};
>> +
>> +/* Supported sensor mode configurations */
>> +static const struct imx334_mode supported_mode = {
>> +	.width = 3840,
>> +	.height = 2160,
>> +	.ppln = 4400,
>> +	.lpfr = 4500,
>> +	.pclk = 594000000,
>> +	.code = MEDIA_BUS_FMT_SRGGB12_1X12,
>> +	.reg_list = {
>> +		.num_of_regs = ARRAY_SIZE(mode_3840x2160_regs),
>> +		.regs = mode_3840x2160_regs,
>> +	},
>> +};
>> +
>> +/**
>> + * to_imx334() - imv334 V4L2 sub-device to imx334 device.
>> + * @subdev: pointer to imx334 V4L2 sub-device
>> + *
>> + * Return: Pointer to imx334 device
>> + */
>> +static inline struct imx334 *to_imx334(struct v4l2_subdev *subdev)
>> +{
>> +	return container_of(subdev, struct imx334, sd);
>> +}
>> +
>> +/**
>> + * imx334_read_reg() - Read registers.
>> + * @imx334: pointer to imx334 device
>> + * @reg: Register address
>> + * @len: Length of bytes to read. Max supported bytes is 4
>> + * @val: Pointer to register value to be filled.
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_read_reg(struct imx334 *imx334, u16 reg, u32 len, u32 *val)
>> +{
>> +	struct i2c_client *client = v4l2_get_subdevdata(&imx334->sd);
>> +	u8 addr_buf[2] = { reg >> 8, reg & 0xff };
>> +	struct i2c_msg msgs[2] = { 0 };
>> +	u8 data_buf[4] = { 0 };
>> +	int ret;
>> +
>> +	if (WARN_ON(len > 4))
>> +		return -EINVAL;
> 
> This function (and the associated write_reg) are for internal use
> only. This mean the only one that can get 'len' wrong is this driver
> itself. Is it worth checking for that ?
> 
>> +
>> +	/* Write register address */
>> +	msgs[0].addr = client->addr;
>> +	msgs[0].flags = 0;
>> +	msgs[0].len = ARRAY_SIZE(addr_buf);
>> +	msgs[0].buf = addr_buf;
>> +
>> +	/* Read data from register */
>> +	msgs[1].addr = client->addr;
>> +	msgs[1].flags = I2C_M_RD;
>> +	msgs[1].len = len;
>> +	msgs[1].buf = &data_buf[4 - len];
>> +
>> +	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
>> +	if (ret != ARRAY_SIZE(msgs))
>> +		return -EIO;
>> +
>> +	*val = get_unaligned_be32(data_buf);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * imx334_write_reg() - Write register
>> + * @imx334: pointer to imx334 device
> 
> writing kernel doc for functions with internal use only is sometimes
> an effort which is nice to do but not required. If you want to go that
> way try to stay consisitent, in this case you started the other
> parameters descriptions with a capital letter.
> 
> Also if you want kernel doc to be generated I think you would need to
> include this file in the Documentation build, otherwise doc does not
> get build as far as I can tell. To be hones I would drop the double **
> and make this regular documentation (I'm no expert on this, maybe wait
> for maintainer's feedback).
> 
>> + * @reg: Register address
>> + * @len: Length of bytes. Max supported bytes is 4
>> + * @val: Register value
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_write_reg(struct imx334 *imx334, u16 reg, u32 len, u32 val)
>> +{
>> +	struct i2c_client *client = v4l2_get_subdevdata(&imx334->sd);
>> +	u8 buf[3] = {0};
>> +	int ret;
>> +	int i;
>> +
>> +	if (WARN_ON(len > 4))
>> +		return -EINVAL;
>> +
>> +	/* Currently we can write to sensor only one byte at a time */
> 
> How so ?
> 
>> +	for (i = 0; i < len; i++) {
>> +		put_unaligned_be16(reg + i, buf);
>> +		buf[2] = (val >> (8 * i)) & 0xff;
>> +		ret = i2c_master_send(client, buf, ARRAY_SIZE(buf));
>> +		if (ret != ARRAY_SIZE(buf)) {
>> +			dev_err_ratelimited(imx334->dev,
>> +					    "write reg 0x%4.4x return err %d",
>> +					    reg, ret);
>> +			return -EIO;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * imx334_write_regs() - Write a list of registers
>> + * @imx334: pointer to imx334 device
>> + * @regs: List of registers to be written
>> + * @len: Length of registers array
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_write_regs(struct imx334 *imx334,
>> +			     const struct imx334_reg *regs, u32 len)
>> +{
>> +	int ret;
>> +	unsigned int i;
>> +
>> +	for (i = 0; i < len; i++) {
>> +		ret = imx334_write_reg(imx334, regs[i].address, 1, regs[i].val);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * imx334_update_controls() - Update control ranges based on streaming mode
>> + * @imx334: pointer to imx334 device
>> + * @mode: pointer to imx334_mode sensor mode
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_update_controls(struct imx334 *imx334,
>> +				  const struct imx334_mode *mode)
>> +{
>> +	int ret;
>> +
>> +	ret = __v4l2_ctrl_s_ctrl(imx334->vblank_ctrl,
>> +				 imx334->lpfr - mode->height);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = __v4l2_ctrl_s_ctrl(imx334->hblank_ctrl, mode->ppln - mode->width);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = __v4l2_ctrl_modify_range(imx334->pclk_ctrl, mode->pclk,
>> +				       mode->pclk, 1, mode->pclk);
>> +	if (ret)
>> +		return ret;
> 
> Does pclk change, as you support a single mode and a single format ?
> 
>> +
>> +	ret = __v4l2_ctrl_modify_range(imx334->exp_ctrl, IMX334_EXPOSURE_MIN,
>> +				       imx334->lpfr - IMX334_EXPOSURE_OFFSET,
>> +				       1, IMX334_EXPOSURE_DEFAULT);
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * imx334_update_exp_gain() - Set updated exposure and gain
>> + * @imx334: pointer to imx334 device
>> + * @exposure: updated exposure value
>> + * @gain: updated analog gain value
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_update_exp_gain(struct imx334 *imx334, u32 exposure, u32 gain)
>> +{
>> +	u32 shutter = 0;
> 
> No need for '= 0', it is immediately assigned below.
> 
>> +	int ret;
>> +
>> +	shutter = imx334->lpfr - exposure;
>> +
>> +	dev_dbg(imx334->dev, "Set long exp %u analog gain %u sh0 %u lpfr %u",
>> +		exposure, gain, shutter, imx334->lpfr);
>> +
>> +	ret = imx334_write_reg(imx334, IMX334_REG_HOLD, 1, 1);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = imx334_write_reg(imx334, IMX334_REG_LPFR, 3, imx334->lpfr);
>> +	if (ret)
>> +		goto error_release_group_hold;
>> +
>> +	ret = imx334_write_reg(imx334, IMX334_REG_SHUTTER, 3, shutter);
>> +	if (ret)
>> +		goto error_release_group_hold;
>> +
>> +	ret = imx334_write_reg(imx334, IMX334_REG_AGAIN, 1, gain);

These lines can be dropped:
-----8<-----
>> +	if (ret)
>> +		goto error_release_group_hold;
>> +
>> +	imx334_write_reg(imx334, IMX334_REG_HOLD, 1, 0);
>> +
>> +	return 0;
>> +
-----8<-----
- as when (ret == 0) the below code works the same as the above two lines

>> +error_release_group_hold:
>> +	imx334_write_reg(imx334, IMX334_REG_HOLD, 1, 0);
>> +	return ret;
>> +}

Thanks,
Andrey

>> +
>> +/**
>> + * imx334_set_ctrl() - Set subdevice control
>> + * @ctrl: pointer to v4l2_ctrl structure
>> + *
>> + * Supported controls:
>> + * - V4L2_CID_VBLANK
>> + * - cluster controls:
>> + *   - V4L2_CID_ANALOGUE_GAIN
>> + *   - V4L2_CID_EXPOSURE
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_set_ctrl(struct v4l2_ctrl *ctrl)
>> +{
>> +	struct imx334 *imx334 =
>> +		container_of(ctrl->handler, struct imx334, ctrl_handler);
>> +	u32 analog_gain;
>> +	u32 exposure;
>> +	int ret;
>> +
>> +	/* Set controls only if sensor is in power on state */
>> +	if (!pm_runtime_get_if_in_use(imx334->dev))
>> +		return 0;
>> +
>> +	/* Handle the cluster for both controls */
>> +	switch (ctrl->id) {
>> +	case V4L2_CID_VBLANK:
>> +		imx334->lpfr = imx334->vblank_ctrl->val +
>> +			imx334->cur_mode->height;
>> +
>> +		dev_dbg(imx334->dev, "Received vblank %u new lpfr %u",
>> +			imx334->vblank_ctrl->val, imx334->lpfr);
>> +
>> +		ret = imx334_update_controls(imx334, imx334->cur_mode);
>> +		break;
>> +	case V4L2_CID_EXPOSURE:
>> +		exposure = ctrl->val;
>> +		analog_gain = imx334->again_ctrl->val;
>> +
>> +		dev_dbg(imx334->dev, "Received exp %u analog gain %u",
>> +			exposure, analog_gain);
>> +
>> +		ret = imx334_update_exp_gain(imx334, exposure, analog_gain);
>> +		break;
>> +	default:
>> +		dev_err(imx334->dev, "Invalid control %d", ctrl->id);
>> +		ret = -EINVAL;
>> +	}
>> +
>> +	pm_runtime_put(imx334->dev);
>> +
>> +	return ret;
>> +}
>> +
>> +/* V4l2 subdevice control ops*/
>> +static const struct v4l2_ctrl_ops imx334_ctrl_ops = {
>> +	.s_ctrl = imx334_set_ctrl,
>> +};
>> +
>> +/**
>> + * imx334_enum_mbus_code() - Enumerate V4L2 sub-device mbus codes
>> + * @sd: pointer to imx334 V4L2 sub-device structure
>> + * @cfg: V4L2 sub-device pad configuration
>> + * @code: V4L2 sub-device code enumeration need to be filled
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_enum_mbus_code(struct v4l2_subdev *sd,
>> +				 struct v4l2_subdev_pad_config *cfg,
>> +				 struct v4l2_subdev_mbus_code_enum *code)
>> +{
>> +	struct imx334 *imx334 = to_imx334(sd);
>> +
>> +	if (code->index > 0)
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&imx334->mutex);
> 
> Do you need to lock ?
> 
>> +	code->code = supported_mode.code;
>> +	mutex_unlock(&imx334->mutex);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * imx334_enum_frame_size() - Enumerate V4L2 sub-device frame sizes
>> + * @sd: pointer to imx334 V4L2 sub-device structure
>> + * @cfg: V4L2 sub-device pad configuration
>> + * @fsize: V4L2 sub-device size enumeration need to be filled
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_enum_frame_size(struct v4l2_subdev *sd,
>> +				  struct v4l2_subdev_pad_config *cfg,
>> +				  struct v4l2_subdev_frame_size_enum *fsize)
>> +{
>> +	struct imx334 *imx334 = to_imx334(sd);
>> +
>> +	if (fsize->index > 0)
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&imx334->mutex);
> 
> Same here, no other subdev IOCTL can interfere with this one.
> 
>> +	if (fsize->code != supported_mode.code) {
>> +		mutex_unlock(&imx334->mutex);
>> +		return -EINVAL;
>> +	}
>> +
>> +	fsize->min_width = supported_mode.width;
>> +	fsize->max_width = fsize->min_width;
>> +	fsize->min_height = supported_mode.height;
>> +	fsize->max_height = fsize->min_height;
>> +	mutex_unlock(&imx334->mutex);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * imx334_fill_pad_format() - Fill subdevice pad format
>> + *                              from selected sensor mode
>> + * @imx334: pointer to imx334 device
>> + * @mode: Pointer to imx334_mode sensor mode
>> + * @fmt: V4L2 sub-device format need to be filled
>> + */
>> +static void imx334_fill_pad_format(struct imx334 *imx334,
>> +				   const struct imx334_mode *mode,
>> +				   struct v4l2_subdev_format *fmt)
>> +{
>> +	fmt->format.width = mode->width;
>> +	fmt->format.height = mode->height;
>> +	fmt->format.code = mode->code;
>> +	fmt->format.field = V4L2_FIELD_NONE;
> 
> Running v4l2-compliance on this driver might report that you need to
> set other fields of v4l2_subdev_format.format (at least the RAW colorspace
> information. I wonder how encoding and quantization apply to a RAW sensor )
> 
>> +}
>> +
>> +/**
>> + * imx334_get_pad_format() - Get subdevice pad format
>> + * @sd: pointer to imx334 V4L2 sub-device structure
>> + * @cfg: V4L2 sub-device pad configuration
>> + * @fmt: V4L2 sub-device format need to be set
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_get_pad_format(struct v4l2_subdev *sd,
>> +				 struct v4l2_subdev_pad_config *cfg,
>> +				 struct v4l2_subdev_format *fmt)
>> +{
>> +	struct imx334 *imx334 = to_imx334(sd);
>> +
>> +	mutex_lock(&imx334->mutex);
>> +
>> +	if (fmt->which == V4L2_SUBDEV_FORMAT_TRY) {
>> +		struct v4l2_mbus_framefmt *framefmt;
>> +
>> +		framefmt = v4l2_subdev_get_try_format(sd, cfg, fmt->pad);
>> +		fmt->format = *framefmt;
>> +	} else {
>> +		imx334_fill_pad_format(imx334, imx334->cur_mode, fmt);
>> +	}
>> +
>> +	mutex_unlock(&imx334->mutex);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * imx334_set_pad_format() - Set subdevice pad format
>> + * @sd: pointer to imx334 V4L2 sub-device structure
>> + * @cfg: V4L2 sub-device pad configuration
>> + * @fmt: V4L2 sub-device format need to be set
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_set_pad_format(struct v4l2_subdev *sd,
>> +				 struct v4l2_subdev_pad_config *cfg,
>> +				 struct v4l2_subdev_format *fmt)
>> +{
>> +	struct imx334 *imx334 = to_imx334(sd);
>> +	const struct imx334_mode *mode;
>> +	int ret = 0;
>> +
>> +	mutex_lock(&imx334->mutex);
>> +
>> +	mode = &supported_mode;
>> +	imx334_fill_pad_format(imx334, mode, fmt);
>> +
>> +	if (fmt->which == V4L2_SUBDEV_FORMAT_TRY) {
>> +		struct v4l2_mbus_framefmt *framefmt;
>> +
>> +		framefmt = v4l2_subdev_get_try_format(sd, cfg, fmt->pad);
>> +		*framefmt = fmt->format;
>> +	} else {
>> +		ret = imx334_update_controls(imx334, mode);
> 
> How can controls change since you have a single supported format ?
> 
> I think with a single format get_pad_fmt and set_pad_fmt could be
> implemented by a single function.
> 
>> +		if (ret)
>> +			dev_err(imx334->dev, "failed to update ctls");
>> +
>> +		imx334->cur_mode = mode;
>> +	}
>> +
>> +	mutex_unlock(&imx334->mutex);
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * imx334_init_pad_cfg() - Initialize sub-device pad configuration
>> + * @sd: pointer to imx334 V4L2 sub-device structure
>> + * @cfg: V4L2 sub-device pad configuration
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_init_pad_cfg(struct v4l2_subdev *sd,
>> +			       struct v4l2_subdev_pad_config *cfg)
>> +{
>> +	struct v4l2_subdev_format fmt = { 0 };
>> +
>> +	fmt.which = cfg ? V4L2_SUBDEV_FORMAT_TRY : V4L2_SUBDEV_FORMAT_ACTIVE;
>> +	fmt.format.width = supported_mode.width;
>> +	fmt.format.height = supported_mode.height;
>> +	fmt.format.code = supported_mode.code;
>> +	fmt.format.field = V4L2_FIELD_NONE;
> 
> You don't use field in set_pad_format. Not a big deal though.
> 
>> +
>> +	return imx334_set_pad_format(sd, cfg, &fmt);
>> +}
>> +
>> +/**
>> + * imx334_start_streaming() - Start sensor stream
>> + * @imx334: pointer to imx334 device
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_start_streaming(struct imx334 *imx334)
>> +{
>> +	const struct imx334_reg_list *reg_list;
>> +	int ret;
>> +
>> +	/* Write sensor mode registers */
>> +	reg_list = &imx334->cur_mode->reg_list;
>> +	ret = imx334_write_regs(imx334, reg_list->regs,
>> +				reg_list->num_of_regs);
>> +	if (ret) {
>> +		dev_err(imx334->dev, "fail to write initial registers");
>> +		return ret;
>> +	}
>> +
>> +	/* Setup handler will write actual exposure and gain */
>> +	ret =  __v4l2_ctrl_handler_setup(imx334->sd.ctrl_handler);
>> +	if (ret) {
>> +		dev_err(imx334->dev, "fail to setup handler");
>> +		return ret;
>> +	}
>> +
>> +	/* Start streaming */
>> +	ret = imx334_write_reg(imx334, IMX334_REG_MODE_SELECT,
>> +			       1, IMX334_MODE_STREAMING);
>> +	if (ret) {
>> +		dev_err(imx334->dev, "fail to start streaming");
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * imx334_stop_streaming() - Stop sensor stream
>> + * @imx334: pointer to imx334 device
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_stop_streaming(struct imx334 *imx334)
>> +{
>> +	return imx334_write_reg(imx334, IMX334_REG_MODE_SELECT,
>> +				1, IMX334_MODE_STANDBY);
>> +}
>> +
>> +/**
>> + * imx334_set_stream() - Enable sensor streaming
>> + * @sd: pointer to imx334 subdevice
>> + * @enable: Set to enable sensor streaming
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_set_stream(struct v4l2_subdev *sd, int enable)
>> +{
>> +	struct imx334 *imx334 = to_imx334(sd);
>> +	int ret;
>> +
>> +	mutex_lock(&imx334->mutex);
>> +
>> +	if (imx334->streaming == enable) {
>> +		mutex_unlock(&imx334->mutex);
>> +		return 0;
>> +	}
>> +
>> +	if (enable) {
>> +		ret = pm_runtime_get_sync(imx334->dev);
>> +		if (ret)
>> +			goto error_power_off;
>> +
>> +		ret = imx334_start_streaming(imx334);
>> +		if (ret)
>> +			goto error_power_off;
>> +	} else {
>> +		imx334_stop_streaming(imx334);
>> +		pm_runtime_put(imx334->dev);
>> +	}
>> +
>> +	imx334->streaming = enable;
>> +
>> +	mutex_unlock(&imx334->mutex);
>> +
>> +	return 0;
>> +
>> +error_power_off:
>> +	pm_runtime_put(imx334->dev);
>> +	mutex_unlock(&imx334->mutex);
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * imx334_detect() - Detect imx334 sensor
>> + * @imx334: pointer to imx334 device
>> + *
>> + * Return: 0 if successful, -EIO if sensor id does not match
>> + */
>> +static int imx334_detect(struct imx334 *imx334)
>> +{
>> +	int ret;
>> +	u32 val;
>> +
>> +	ret = imx334_read_reg(imx334, IMX334_REG_ID, 2, &val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (val != IMX334_ID) {
>> +		dev_err(imx334->dev, "chip id mismatch: %x!=%x",
>> +			IMX334_ID, val);
>> +		return -EIO;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/* V4l2 subdevice ops */
>> +static const struct v4l2_subdev_video_ops imx334_video_ops = {
>> +	.s_stream = imx334_set_stream,
>> +};
>> +
>> +static const struct v4l2_subdev_pad_ops imx334_pad_ops = {
>> +	.init_cfg = imx334_init_pad_cfg,
>> +	.enum_mbus_code = imx334_enum_mbus_code,
>> +	.enum_frame_size = imx334_enum_frame_size,
>> +	.get_fmt = imx334_get_pad_format,
>> +	.set_fmt = imx334_set_pad_format,
>> +};
>> +
>> +static const struct v4l2_subdev_ops imx334_subdev_ops = {
>> +	.video = &imx334_video_ops,
>> +	.pad = &imx334_pad_ops,
>> +};
>> +
>> +static const struct media_entity_operations imx334_subdev_entity_ops = {
>> +	.link_validate = v4l2_subdev_link_validate,
>> +};
> 
> Is link_validate called on sensor subdev ? My understanding is that
> they're called on the sink entity, but I might be mistaken.
> 
>> +
>> +/**
>> + * imx334_power_on() - Sensor power on sequence
>> + * @dev: pointer to i2c device
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_power_on(struct device *dev)
>> +{
>> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>> +	struct imx334 *imx334 = to_imx334(sd);
>> +	int ret;
>> +
>> +	gpiod_set_value_cansleep(imx334->reset_gpio, 1);
>> +
>> +	ret = clk_prepare_enable(imx334->inclk);
>> +	if (ret) {
>> +		dev_err(imx334->dev, "fail to enable inclk");
>> +		goto error_reset;
>> +	}
>> +
>> +	usleep_range(18000, 20000);
>> +
>> +	return 0;
>> +
>> +error_reset:
>> +	gpiod_set_value_cansleep(imx334->reset_gpio, 0);
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * imx334_power_off() - Sensor power off sequence
>> + * @dev: pointer to i2c device
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_power_off(struct device *dev)
>> +{
>> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>> +	struct imx334 *imx334 = to_imx334(sd);
>> +
>> +	gpiod_set_value_cansleep(imx334->reset_gpio, 0);
>> +
>> +	clk_disable_unprepare(imx334->inclk);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * imx334_init_controls() - Initialize sensor subdevice controls
>> + * @imx334: pointer to imx334 device
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_init_controls(struct imx334 *imx334)
>> +{
>> +	struct v4l2_ctrl_handler *ctrl_hdlr = &imx334->ctrl_handler;
>> +	const struct imx334_mode *mode = imx334->cur_mode;
>> +	u32 hblank;
>> +	u32 vblank;
>> +	int ret;
>> +
>> +	ret = v4l2_ctrl_handler_init(ctrl_hdlr, 5);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Serialize controls with sensor device */
>> +	ctrl_hdlr->lock = &imx334->mutex;
>> +
>> +	/* Initialize exposure and gain */
>> +	imx334->exp_ctrl = v4l2_ctrl_new_std(ctrl_hdlr,
>> +					     &imx334_ctrl_ops,
>> +					     V4L2_CID_EXPOSURE,
>> +					     IMX334_EXPOSURE_MIN,
>> +					     mode->lpfr,
>> +					     IMX334_EXPOSURE_STEP,
>> +					     IMX334_EXPOSURE_DEFAULT);
>> +
>> +	imx334->again_ctrl = v4l2_ctrl_new_std(ctrl_hdlr,
>> +					       &imx334_ctrl_ops,
>> +					       V4L2_CID_ANALOGUE_GAIN,
>> +					       IMX334_AGAIN_MIN,
>> +					       IMX334_AGAIN_MAX,
>> +					       IMX334_AGAIN_STEP,
>> +					       IMX334_AGAIN_DEFAULT);
>> +
>> +	v4l2_ctrl_cluster(2, &imx334->exp_ctrl);
>> +
>> +	vblank = mode->lpfr - mode->height;
>> +	imx334->vblank_ctrl = v4l2_ctrl_new_std(ctrl_hdlr,
>> +						&imx334_ctrl_ops,
>> +						V4L2_CID_VBLANK,
>> +						IMX334_LPFR_MIN - mode->height,
>> +						IMX334_LPFR_MAX - mode->height,
>> +						1, vblank);
>> +
>> +	/* Read only controls */
>> +	imx334->pclk_ctrl = v4l2_ctrl_new_std(ctrl_hdlr,
>> +					      &imx334_ctrl_ops,
>> +					      V4L2_CID_PIXEL_RATE,
>> +					      mode->pclk, mode->pclk,
>> +					      1, mode->pclk);
>> +	if (imx334->pclk_ctrl)
>> +		imx334->pclk_ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> 
> You can set the READ_ONLY flags after the below:
>          if (ctrl_hdlr->error)
> 
> to avoid checking for the control validity here and below
> 
> 
>> +
>> +	hblank = mode->ppln - mode->width;
>> +	imx334->hblank_ctrl = v4l2_ctrl_new_std(ctrl_hdlr,
>> +						&imx334_ctrl_ops,
>> +						V4L2_CID_HBLANK,
>> +						IMX334_REG_MIN,
>> +						IMX334_REG_MAX,
>> +						1, hblank);
>> +	if (imx334->hblank_ctrl)
>> +		imx334->hblank_ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
>> +
>> +	if (ctrl_hdlr->error) {
>> +		ret = ctrl_hdlr->error;
>> +		dev_err(imx334->dev, "control init failed: %d", ret);
>> +		goto error;
> 
> You can free the handler here and return cltr_hdlr->error directly
> here.
> 
>> +	}
>> +
>> +	imx334->sd.ctrl_handler = ctrl_hdlr;
>> +
>> +	return 0;
>> +
>> +error:
>> +	v4l2_ctrl_handler_free(ctrl_hdlr);
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * imx334_probe() - I2C client device binding
>> + * @client: pointer to i2c client device
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_probe(struct i2c_client *client)
>> +{
>> +	struct imx334 *imx334;
>> +	unsigned long rate;
>> +	int ret;
>> +
>> +	imx334 = devm_kzalloc(&client->dev, sizeof(*imx334), GFP_KERNEL);
>> +	if (!imx334)
>> +		return -ENOMEM;
>> +
>> +	mutex_init(&imx334->mutex);
>> +
>> +	imx334->dev = &client->dev;
>> +
>> +	/* Initialize subdev */
>> +	v4l2_i2c_subdev_init(&imx334->sd, client, &imx334_subdev_ops);
>> +
>> +	/* Request optional reset pin */
>> +	imx334->reset_gpio = gpiod_get_optional(imx334->dev, "reset",
>> +						GPIOD_OUT_LOW);
> 
> devm_ ?
> 
>> +	if (IS_ERR(imx334->reset_gpio)) {
>> +		ret = PTR_ERR(imx334->reset_gpio);
>> +		dev_err(imx334->dev, "failed to get reset gpio %d", ret);
>> +		goto error_mutex_destroy;
>> +	}
>> +
>> +	/* Get sensor input clock */
>> +	imx334->inclk = devm_clk_get(imx334->dev, "inclk");
>> +	if (IS_ERR(imx334->inclk)) {
>> +		ret = PTR_ERR(imx334->inclk);
>> +		dev_err(imx334->dev, "could not get inclk");
>> +		goto error_mutex_destroy;
>> +	}
>> +
>> +	rate = clk_get_rate(imx334->inclk);
>> +	if (rate != IMX334_INCLK_RATE) {
>> +		dev_err(imx334->dev, "inclk frequency mismatch");
>> +		ret = -EINVAL;
>> +		goto error_mutex_destroy;
>> +	}
> 
> You can intialize the mutex here to avoid a few goto here above
> 
>> +
>> +	ret = imx334_power_on(imx334->dev);
>> +	if (ret) {
>> +		dev_err(imx334->dev, "failed to power-on the sensor");
>> +		goto error_mutex_destroy;
>> +	}
>> +
>> +	/* Check module identity */
>> +	ret = imx334_detect(imx334);
>> +	if (ret) {
>> +		dev_err(imx334->dev, "failed to find sensor: %d", ret);
>> +		goto error_power_off;
>> +	}
>> +
>> +	/* Set default mode to max resolution */
>> +	imx334->cur_mode = &supported_mode;
>> +	imx334->lpfr = imx334->cur_mode->lpfr;
>> +
>> +	ret = imx334_init_controls(imx334);
>> +	if (ret) {
>> +		dev_err(imx334->dev, "failed to init controls: %d", ret);
>> +		goto error_power_off;
>> +	}
>> +
>> +	/* Initialize subdev */
>> +	imx334->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
>> +	imx334->sd.entity.ops = &imx334_subdev_entity_ops;
>> +	imx334->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
>> +
>> +	/* Initialize source pad */
>> +	imx334->pad.flags = MEDIA_PAD_FL_SOURCE;
>> +	ret = media_entity_pads_init(&imx334->sd.entity, 1, &imx334->pad);
>> +	if (ret) {
>> +		dev_err(imx334->dev, "failed to init entity pads: %d", ret);
>> +		goto error_handler_free;
>> +	}
>> +
>> +	ret = v4l2_async_register_subdev_sensor_common(&imx334->sd);
> 
> _sensor_common() tries to parse the firware interface to search for
> lens and flash subdevices. I don't see them mentioned in bindings, do
> you need them or should this just be v4l2_async_register_subdev() ?
> 
> Anyway, driver looks good, mostly minor comments
> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
> 
> Thanks
>    j
> 
>> +	if (ret < 0) {
>> +		dev_err(imx334->dev,
>> +			"failed to register async subdev: %d", ret);
>> +		goto error_media_entity;
>> +	}
>> +
>> +	pm_runtime_set_active(imx334->dev);
>> +	pm_runtime_enable(imx334->dev);
>> +	pm_runtime_idle(imx334->dev);
>> +
>> +	return 0;
>> +
>> +error_media_entity:
>> +	media_entity_cleanup(&imx334->sd.entity);
>> +error_handler_free:
>> +	v4l2_ctrl_handler_free(imx334->sd.ctrl_handler);
>> +error_power_off:
>> +	imx334_power_off(imx334->dev);
>> +error_mutex_destroy:
>> +	mutex_destroy(&imx334->mutex);
>> +
>> +	return ret;
>> +}
>> +
>> +/**
>> + * imx334_remove() - I2C client device unbinding
>> + * @client: pointer to I2C client device
>> + *
>> + * Return: 0 if successful, error code otherwise.
>> + */
>> +static int imx334_remove(struct i2c_client *client)
>> +{
>> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> +	struct imx334 *imx334 = to_imx334(sd);
>> +
>> +	v4l2_async_unregister_subdev(sd);
>> +	media_entity_cleanup(&sd->entity);
>> +	v4l2_ctrl_handler_free(sd->ctrl_handler);
>> +
>> +	pm_runtime_disable(&client->dev);
>> +	pm_runtime_suspended(&client->dev);
>> +
>> +	mutex_destroy(&imx334->mutex);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct dev_pm_ops imx334_pm_ops = {
>> +	SET_RUNTIME_PM_OPS(imx334_power_off, imx334_power_on, NULL)
>> +};
>> +
>> +static const struct of_device_id imx334_of_match[] = {
>> +	{ .compatible = "sony,imx334" },
>> +	{ }
>> +};
>> +
>> +MODULE_DEVICE_TABLE(of, imx334_of_match);
>> +
>> +static struct i2c_driver imx334_driver = {
>> +	.probe_new = imx334_probe,
>> +	.remove = imx334_remove,
>> +	.driver = {
>> +		.name = IMX334_DRV_NAME,
>> +		.pm = &imx334_pm_ops,
>> +		.of_match_table = imx334_of_match,
>> +	},
>> +};
>> +
>> +module_i2c_driver(imx334_driver);
>> +
>> +MODULE_DESCRIPTION("Sony imx334 sensor driver");
>> +MODULE_LICENSE("GPL");
>> --
>> 2.11.0
>>