Re: [PATCH v3 1/3] media: pci: intel: ivsc: Add CSI submodule

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

Hi Wentong,

On Mon, Mar 27, 2023 at 02:23:06PM +0800, Wentong Wu wrote:
> CSI is a submodule of IVSC which can route camera sensor data
> to the outbound MIPI CSI-2 interface.
> 
> The interface communicating with firmware is via MEI. There is
> a separate MEI UUID, which this driver uses to enumerate.
> 
> To route camera sensor data to host, the information of link
> frequency and number of data lanes is sent to firmware by
> sending MEI command when starting stream.
> 
> CSI also provides a privacy mode. When privacy mode is turned
> on, camera sensor can't be used. This means that both IVSC and
> host Image Processing Unit(IPU) can't get image data. And when
> this mode is turned on, host Image Processing Unit(IPU) driver
> is informed via v4l2 control callback, so that user can be
> notified.
> 
> Signed-off-by: Wentong Wu <wentong.wu@intel.com>
> ---
>  drivers/media/pci/Kconfig                 |   1 +
>  drivers/media/pci/intel/Makefile          |   2 +
>  drivers/media/pci/intel/ivsc/Kconfig      |  12 +
>  drivers/media/pci/intel/ivsc/Makefile     |   7 +
>  drivers/media/pci/intel/ivsc/csi_bridge.c | 332 +++++++++++++
>  drivers/media/pci/intel/ivsc/csi_bridge.h | 122 +++++
>  drivers/media/pci/intel/ivsc/mei_csi.c    | 775 ++++++++++++++++++++++++++++++
>  7 files changed, 1251 insertions(+)
>  create mode 100644 drivers/media/pci/intel/ivsc/Kconfig
>  create mode 100644 drivers/media/pci/intel/ivsc/Makefile
>  create mode 100644 drivers/media/pci/intel/ivsc/csi_bridge.c
>  create mode 100644 drivers/media/pci/intel/ivsc/csi_bridge.h
>  create mode 100644 drivers/media/pci/intel/ivsc/mei_csi.c

I'm commenting just mei_csi this time...

> diff --git a/drivers/media/pci/intel/ivsc/mei_csi.c b/drivers/media/pci/intel/ivsc/mei_csi.c
> new file mode 100644
> index 0000000..6a01537
> --- /dev/null
> +++ b/drivers/media/pci/intel/ivsc/mei_csi.c
> @@ -0,0 +1,775 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2023 Intel Corporation. All rights reserved.
> + * Intel Visual Sensing Controller CSI Linux driver
> + */
> +
> +/*
> + * To set ownership of CSI-2 link and to configure CSI-2 link, there
> + * are specific commands, which are sent via MEI protocol. The send
> + * command function uses "completion" as a synchronization mechanism.
> + * The response for command is received via a mei callback which wakes
> + * up the caller. There can be only one outstanding command at a time.
> + */
> +
> +#include <linux/completion.h>
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/math64.h>
> +#include <linux/mei_cl_bus.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/slab.h>
> +#include <linux/units.h>
> +#include <linux/uuid.h>
> +#include <linux/workqueue.h>
> +
> +#include <media/v4l2-async.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +#define MEI_CSI_DRIVER_NAME "ivsc_csi"
> +
> +/* the 5s used here is based on experiment */
> +#define CSI_CMD_TIMEOUT (5 * HZ)
> +/* to setup CSI-2 link an extra delay needed and determined experimentally */
> +#define CSI_FW_READY_DELAY_MS 100
> +/* link frequency unit is 100kHz */
> +#define CSI_LINK_FREQ(x) ((u32)(div_u64(x, 100 * HZ_PER_KHZ)))
> +
> +/*
> + * identify the command id supported by firmware
> + * IPC, as well as the privacy notification id
> + * used when processing privacy event.
> + */
> +enum csi_cmd_id {
> +	/* used to set csi ownership */
> +	CSI_SET_OWNER = 0,
> +
> +	/* used to configure CSI-2 link */
> +	CSI_SET_CONF = 2,
> +
> +	/* privacy notification id used when privacy state changes */
> +	CSI_PRIVACY_NOTIF = 6,
> +};
> +
> +/* CSI-2 link ownership definition */
> +enum csi_link_owner {
> +	CSI_LINK_IVSC,
> +	CSI_LINK_HOST,
> +};
> +
> +/* privacy status definition */
> +enum ivsc_privacy_status {
> +	CSI_PRIVACY_OFF,
> +	CSI_PRIVACY_ON,
> +	CSI_PRIVACY_MAX,
> +};
> +
> +enum csi_pads {
> +	CSI_PAD_SOURCE,
> +	CSI_PAD_SINK,
> +	CSI_NUM_PADS
> +};
> +
> +/* configuration of the CSI-2 link between host and IVSC */
> +struct csi_link_cfg {
> +	/* number of data lanes used on the CSI-2 link */
> +	u32 nr_of_lanes;
> +
> +	/* frequency of the CSI-2 link */
> +	u32 link_freq;
> +
> +	/* for future use */
> +	u32 rsvd[2];
> +} __packed;
> +
> +/* CSI command structure */
> +struct csi_cmd {
> +	u32 cmd_id;
> +	union _cmd_param {
> +		u32 param;
> +		struct csi_link_cfg conf;
> +	} param;
> +} __packed;
> +
> +/* CSI notification structure */
> +struct csi_notif {
> +	u32 cmd_id;
> +	int status;
> +	union _resp_cont {
> +		u32 cont;
> +		struct csi_link_cfg conf;
> +	} cont;
> +} __packed;
> +
> +struct mei_csi {
> +	struct mei_cl_device *cldev;
> +
> +	/* command response */
> +	struct csi_notif cmd_response;
> +	/* used to wait for command response from firmware */
> +	struct completion cmd_completion;
> +	/* protect command download */
> +	struct mutex lock;
> +
> +	struct v4l2_subdev subdev;
> +	struct v4l2_subdev *remote;
> +	struct v4l2_async_notifier notifier;
> +	struct v4l2_ctrl_handler ctrl_handler;
> +	struct v4l2_ctrl *privacy_ctrl;
> +	unsigned int remote_pad;
> +	/* start streaming or not */
> +	int streaming;
> +
> +	struct media_pad pads[CSI_NUM_PADS];
> +	struct v4l2_mbus_framefmt format_mbus[CSI_NUM_PADS];
> +
> +	/* number of data lanes used on the CSI-2 link */
> +	u32 nr_of_lanes;
> +	/* frequency of the CSI-2 link */
> +	u64 link_freq;
> +
> +	/* privacy status */
> +	enum ivsc_privacy_status status;
> +};
> +
> +static const struct v4l2_mbus_framefmt mei_csi_format_mbus_default = {
> +	.width = 1,
> +	.height = 1,
> +	.code = MEDIA_BUS_FMT_Y8_1X8,
> +	.field = V4L2_FIELD_NONE,
> +};
> +
> +int csi_bridge_init(struct mei_cl_device *csi_dev);
> +
> +static inline struct mei_csi *notifier_to_csi(struct v4l2_async_notifier *n)
> +{
> +	return container_of(n, struct mei_csi, notifier);
> +}
> +
> +static inline struct mei_csi *sd_to_csi(struct v4l2_subdev *sd)
> +{
> +	return container_of(sd, struct mei_csi, subdev);
> +}
> +
> +/* send a command to firmware and mutex must be held by caller */
> +static int mei_csi_send(struct mei_csi *csi, u8 *buf, size_t len)
> +{
> +	struct csi_cmd *cmd = (struct csi_cmd *)buf;
> +	int ret;
> +
> +	reinit_completion(&csi->cmd_completion);
> +
> +	ret = mei_cldev_send(csi->cldev, buf, len);
> +	if (ret < 0)
> +		goto out;
> +
> +	ret = wait_for_completion_killable_timeout(&csi->cmd_completion,
> +						   CSI_CMD_TIMEOUT);
> +	if (ret < 0) {
> +		goto out;
> +	} else if (!ret) {
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}
> +
> +	/* command response status */
> +	ret = csi->cmd_response.status;
> +	if (ret) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	if (csi->cmd_response.cmd_id != cmd->cmd_id)
> +		ret = -EINVAL;
> +
> +out:
> +	return ret;
> +}
> +
> +/* set CSI-2 link ownership */
> +static int csi_set_link_owner(struct mei_csi *csi, enum csi_link_owner owner)
> +{
> +	struct csi_cmd cmd = { 0 };
> +	size_t cmd_size;
> +	int ret;
> +
> +	cmd.cmd_id = CSI_SET_OWNER;
> +	cmd.param.param = owner;
> +	cmd_size = sizeof(cmd.cmd_id) + sizeof(cmd.param.param);

In some cases you're using memset and in others not. If you don't need
memset, I'd prefer assigning the fields in variable declaration instead.

> +
> +	mutex_lock(&csi->lock);
> +
> +	ret = mei_csi_send(csi, (u8 *)&cmd, cmd_size);
> +
> +	mutex_unlock(&csi->lock);
> +
> +	return ret;
> +}
> +
> +/* configure CSI-2 link between host and IVSC */
> +static int csi_set_link_cfg(struct mei_csi *csi)
> +{
> +	struct csi_cmd cmd = { 0 };
> +	size_t cmd_size;
> +	int ret;
> +
> +	cmd.cmd_id = CSI_SET_CONF;
> +	cmd.param.conf.nr_of_lanes = csi->nr_of_lanes;
> +	cmd.param.conf.link_freq = CSI_LINK_FREQ(csi->link_freq);
> +	cmd_size = sizeof(cmd.cmd_id) + sizeof(cmd.param.conf);

Ditto.

> +
> +	mutex_lock(&csi->lock);
> +
> +	ret = mei_csi_send(csi, (u8 *)&cmd, cmd_size);
> +	/*
> +	 * wait configuration ready if download success. placing
> +	 * delay under mutex is to make sure current command flow
> +	 * completed before starting a possible new one.
> +	 */
> +	if (!ret)
> +		msleep(CSI_FW_READY_DELAY_MS);
> +
> +	mutex_unlock(&csi->lock);
> +
> +	return ret;
> +}
> +
> +/* callback for receive */
> +static void mei_csi_rx(struct mei_cl_device *cldev)
> +{
> +	struct mei_csi *csi = mei_cldev_get_drvdata(cldev);
> +	struct csi_notif notif = { 0 };
> +	int ret;
> +
> +	ret = mei_cldev_recv(cldev, (u8 *)&notif, sizeof(notif));
> +	if (ret < 0) {
> +		dev_err(&cldev->dev, "recv error: %d\n", ret);
> +		return;
> +	}
> +
> +	switch (notif.cmd_id) {
> +	case CSI_PRIVACY_NOTIF:
> +		if (notif.cont.cont < CSI_PRIVACY_MAX) {
> +			csi->status = notif.cont.cont;
> +			v4l2_ctrl_s_ctrl(csi->privacy_ctrl, csi->status);
> +		}
> +		break;
> +	case CSI_SET_OWNER:
> +	case CSI_SET_CONF:
> +		memcpy(&csi->cmd_response, &notif, ret);
> +
> +		complete(&csi->cmd_completion);
> +		break;
> +	default:
> +		break;
> +	}
> +}
> +
> +static int mei_csi_pre_streamon(struct v4l2_subdev *sd, u32 flags)
> +{
> +	struct v4l2_querymenu qm = { .id = V4L2_CID_LINK_FREQ, };
> +	struct v4l2_mbus_config mbus_config = { 0 };
> +	struct mei_csi *csi = sd_to_csi(sd);
> +	struct v4l2_ctrl *ctrl;
> +	int ret = 0;
> +
> +	if (!csi->remote)
> +		return -ENODEV;
> +
> +	ret = v4l2_subdev_call(csi->remote, pad, get_mbus_config,
> +			       csi->remote_pad, &mbus_config);
> +	if (ret)
> +		return ret;

You're already parsing the endpoint in probe(). Do you need this, assuming
the sensor has a static lane configuration? Virtually all do.

Could this all be done via the s_stream() op instead?

> +
> +	if (mbus_config.type != V4L2_MBUS_CSI2_DPHY)
> +		return -EINVAL;
> +
> +	csi->nr_of_lanes = mbus_config.bus.mipi_csi2.num_data_lanes;
> +
> +	ctrl = v4l2_ctrl_find(csi->remote->ctrl_handler, V4L2_CID_LINK_FREQ);
> +	if (!ctrl)
> +		return -EINVAL;
> +	qm.index = v4l2_ctrl_g_ctrl(ctrl);
> +
> +	ret = v4l2_querymenu(csi->remote->ctrl_handler, &qm);
> +	if (ret)
> +		return ret;
> +
> +	csi->link_freq = qm.value;
> +
> +	return ret;
> +}
> +
> +static int mei_csi_set_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	struct mei_csi *csi = sd_to_csi(sd);
> +	int ret = 0;
> +
> +	if (enable && csi->streaming == 0) {
> +		/* switch CSI-2 link to host */
> +		ret = csi_set_link_owner(csi, CSI_LINK_HOST);
> +		if (ret < 0)
> +			goto err;
> +
> +		/* configure CSI-2 link */
> +		ret = csi_set_link_cfg(csi);
> +		if (ret < 0)
> +			goto err;
> +
> +		ret = v4l2_subdev_call(csi->remote, video, s_stream, 1);
> +		if (ret)
> +			goto err;
> +	} else if (!enable && csi->streaming == 1) {
> +		v4l2_subdev_call(csi->remote, video, s_stream, 0);
> +
> +		/* switch CSI-2 link to IVSC */
> +		ret = csi_set_link_owner(csi, CSI_LINK_IVSC);
> +		if (ret < 0)
> +			goto err;

I'd complain (e.g. dev_warn()) but return zero in this case. There's not
much if anything the caller can do with this.

> +	}
> +
> +	csi->streaming = enable;
> +
> +err:
> +	return ret;
> +}
> +
> +static struct v4l2_mbus_framefmt *
> +mei_csi_get_pad_format(struct v4l2_subdev *sd,
> +		       struct v4l2_subdev_state *sd_state,
> +		       unsigned int pad, u32 which)
> +{
> +	struct mei_csi *csi = sd_to_csi(sd);
> +
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_format(sd, sd_state, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &csi->format_mbus[pad];
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static int mei_csi_init_cfg(struct v4l2_subdev *sd,
> +			    struct v4l2_subdev_state *sd_state)
> +{
> +	struct v4l2_mbus_framefmt *mbusformat;
> +	struct mei_csi *csi = sd_to_csi(sd);
> +	unsigned int i;
> +
> +	mutex_lock(&csi->lock);
> +
> +	for (i = 0; i < sd->entity.num_pads; i++) {
> +		mbusformat = v4l2_subdev_get_try_format(sd, sd_state, i);
> +		*mbusformat = mei_csi_format_mbus_default;
> +	}
> +
> +	mutex_unlock(&csi->lock);
> +
> +	return 0;
> +}
> +
> +static int mei_csi_get_fmt(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_state *sd_state,
> +			   struct v4l2_subdev_format *format)
> +{
> +	struct v4l2_mbus_framefmt *mbusformat;
> +	struct mei_csi *csi = sd_to_csi(sd);
> +
> +	mutex_lock(&csi->lock);
> +
> +	mbusformat = mei_csi_get_pad_format(sd, sd_state, format->pad,
> +					    format->which);
> +	if (mbusformat)
> +		format->format = *mbusformat;
> +
> +	mutex_unlock(&csi->lock);
> +
> +	return 0;
> +}

It'd be nice to have also enum_mbus_code support. Video mux of course
didn't have this either. Something that could be done in the framework,
including validating the mbus format.

> +
> +static int mei_csi_set_fmt(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_state *sd_state,
> +			   struct v4l2_subdev_format *format)
> +{
> +	struct v4l2_mbus_framefmt *source_mbusformat;
> +	struct v4l2_mbus_framefmt *mbusformat;
> +	struct mei_csi *csi = sd_to_csi(sd);
> +	struct media_pad *pad;
> +
> +	mbusformat = mei_csi_get_pad_format(sd, sd_state, format->pad,
> +					    format->which);
> +	if (!mbusformat)
> +		return -EINVAL;
> +
> +	source_mbusformat = mei_csi_get_pad_format(sd, sd_state,
> +						   CSI_PAD_SOURCE,
> +						   format->which);
> +	if (!source_mbusformat)
> +		return -EINVAL;
> +
> +	v4l_bound_align_image(&format->format.width, 1, 65536, 0,
> +			      &format->format.height, 1, 65536, 0, 0);
> +
> +	switch (format->format.code) {
> +	case MEDIA_BUS_FMT_RGB444_1X12:
> +	case MEDIA_BUS_FMT_RGB444_2X8_PADHI_BE:
> +	case MEDIA_BUS_FMT_RGB444_2X8_PADHI_LE:
> +	case MEDIA_BUS_FMT_RGB555_2X8_PADHI_BE:
> +	case MEDIA_BUS_FMT_RGB555_2X8_PADHI_LE:
> +	case MEDIA_BUS_FMT_RGB565_1X16:
> +	case MEDIA_BUS_FMT_BGR565_2X8_BE:
> +	case MEDIA_BUS_FMT_BGR565_2X8_LE:
> +	case MEDIA_BUS_FMT_RGB565_2X8_BE:
> +	case MEDIA_BUS_FMT_RGB565_2X8_LE:
> +	case MEDIA_BUS_FMT_RGB666_1X18:
> +	case MEDIA_BUS_FMT_RBG888_1X24:
> +	case MEDIA_BUS_FMT_RGB666_1X24_CPADHI:
> +	case MEDIA_BUS_FMT_BGR888_1X24:
> +	case MEDIA_BUS_FMT_GBR888_1X24:
> +	case MEDIA_BUS_FMT_RGB888_1X24:
> +	case MEDIA_BUS_FMT_RGB888_2X12_BE:
> +	case MEDIA_BUS_FMT_RGB888_2X12_LE:
> +	case MEDIA_BUS_FMT_ARGB8888_1X32:
> +	case MEDIA_BUS_FMT_RGB888_1X32_PADHI:
> +	case MEDIA_BUS_FMT_RGB101010_1X30:
> +	case MEDIA_BUS_FMT_RGB121212_1X36:
> +	case MEDIA_BUS_FMT_RGB161616_1X48:
> +	case MEDIA_BUS_FMT_Y8_1X8:
> +	case MEDIA_BUS_FMT_UV8_1X8:
> +	case MEDIA_BUS_FMT_UYVY8_1_5X8:
> +	case MEDIA_BUS_FMT_VYUY8_1_5X8:
> +	case MEDIA_BUS_FMT_YUYV8_1_5X8:
> +	case MEDIA_BUS_FMT_YVYU8_1_5X8:
> +	case MEDIA_BUS_FMT_UYVY8_2X8:
> +	case MEDIA_BUS_FMT_VYUY8_2X8:
> +	case MEDIA_BUS_FMT_YUYV8_2X8:
> +	case MEDIA_BUS_FMT_YVYU8_2X8:
> +	case MEDIA_BUS_FMT_Y10_1X10:
> +	case MEDIA_BUS_FMT_UYVY10_2X10:
> +	case MEDIA_BUS_FMT_VYUY10_2X10:
> +	case MEDIA_BUS_FMT_YUYV10_2X10:
> +	case MEDIA_BUS_FMT_YVYU10_2X10:
> +	case MEDIA_BUS_FMT_Y12_1X12:
> +	case MEDIA_BUS_FMT_UYVY12_2X12:
> +	case MEDIA_BUS_FMT_VYUY12_2X12:
> +	case MEDIA_BUS_FMT_YUYV12_2X12:
> +	case MEDIA_BUS_FMT_YVYU12_2X12:
> +	case MEDIA_BUS_FMT_UYVY8_1X16:
> +	case MEDIA_BUS_FMT_VYUY8_1X16:
> +	case MEDIA_BUS_FMT_YUYV8_1X16:
> +	case MEDIA_BUS_FMT_YVYU8_1X16:
> +	case MEDIA_BUS_FMT_YDYUYDYV8_1X16:
> +	case MEDIA_BUS_FMT_UYVY10_1X20:
> +	case MEDIA_BUS_FMT_VYUY10_1X20:
> +	case MEDIA_BUS_FMT_YUYV10_1X20:
> +	case MEDIA_BUS_FMT_YVYU10_1X20:
> +	case MEDIA_BUS_FMT_VUY8_1X24:
> +	case MEDIA_BUS_FMT_YUV8_1X24:
> +	case MEDIA_BUS_FMT_UYYVYY8_0_5X24:
> +	case MEDIA_BUS_FMT_UYVY12_1X24:
> +	case MEDIA_BUS_FMT_VYUY12_1X24:
> +	case MEDIA_BUS_FMT_YUYV12_1X24:
> +	case MEDIA_BUS_FMT_YVYU12_1X24:
> +	case MEDIA_BUS_FMT_YUV10_1X30:
> +	case MEDIA_BUS_FMT_UYYVYY10_0_5X30:
> +	case MEDIA_BUS_FMT_AYUV8_1X32:
> +	case MEDIA_BUS_FMT_UYYVYY12_0_5X36:
> +	case MEDIA_BUS_FMT_YUV12_1X36:
> +	case MEDIA_BUS_FMT_YUV16_1X48:
> +	case MEDIA_BUS_FMT_UYYVYY16_0_5X48:
> +	case MEDIA_BUS_FMT_JPEG_1X8:
> +	case MEDIA_BUS_FMT_AHSV8888_1X32:
> +	case MEDIA_BUS_FMT_SBGGR8_1X8:
> +	case MEDIA_BUS_FMT_SGBRG8_1X8:
> +	case MEDIA_BUS_FMT_SGRBG8_1X8:
> +	case MEDIA_BUS_FMT_SRGGB8_1X8:
> +	case MEDIA_BUS_FMT_SBGGR10_1X10:
> +	case MEDIA_BUS_FMT_SGBRG10_1X10:
> +	case MEDIA_BUS_FMT_SGRBG10_1X10:
> +	case MEDIA_BUS_FMT_SRGGB10_1X10:
> +	case MEDIA_BUS_FMT_SBGGR12_1X12:
> +	case MEDIA_BUS_FMT_SGBRG12_1X12:
> +	case MEDIA_BUS_FMT_SGRBG12_1X12:
> +	case MEDIA_BUS_FMT_SRGGB12_1X12:
> +	case MEDIA_BUS_FMT_SBGGR14_1X14:
> +	case MEDIA_BUS_FMT_SGBRG14_1X14:
> +	case MEDIA_BUS_FMT_SGRBG14_1X14:
> +	case MEDIA_BUS_FMT_SRGGB14_1X14:
> +	case MEDIA_BUS_FMT_SBGGR16_1X16:
> +	case MEDIA_BUS_FMT_SGBRG16_1X16:
> +	case MEDIA_BUS_FMT_SGRBG16_1X16:
> +	case MEDIA_BUS_FMT_SRGGB16_1X16:
> +		break;
> +	default:
> +		format->format.code = MEDIA_BUS_FMT_Y8_1X8;
> +		break;
> +	}
> +	if (format->format.field == V4L2_FIELD_ANY)
> +		format->format.field = V4L2_FIELD_NONE;
> +
> +	mutex_lock(&csi->lock);
> +
> +	pad = &csi->pads[format->pad];
> +	if (pad->flags & MEDIA_PAD_FL_SOURCE)
> +		format->format = csi->format_mbus[CSI_PAD_SINK];
> +
> +	*mbusformat = format->format;
> +
> +	if (pad->flags & MEDIA_PAD_FL_SINK)
> +		*source_mbusformat = format->format;
> +
> +	mutex_unlock(&csi->lock);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_video_ops mei_csi_video_ops = {
> +	.s_stream = mei_csi_set_stream,
> +	.pre_streamon = mei_csi_pre_streamon,
> +};
> +
> +static const struct v4l2_subdev_pad_ops mei_csi_pad_ops = {
> +	.init_cfg = mei_csi_init_cfg,
> +	.get_fmt = mei_csi_get_fmt,
> +	.set_fmt = mei_csi_set_fmt,
> +};
> +
> +static const struct v4l2_subdev_ops mei_csi_subdev_ops = {
> +	.video = &mei_csi_video_ops,
> +	.pad = &mei_csi_pad_ops,
> +};
> +
> +static const struct media_entity_operations mei_csi_entity_ops = {
> +	.link_validate = v4l2_subdev_link_validate,
> +};
> +
> +static int mei_csi_notify_bound(struct v4l2_async_notifier *notifier,
> +				struct v4l2_subdev *subdev,
> +				struct v4l2_async_subdev *asd)
> +{
> +	struct mei_csi *csi = notifier_to_csi(notifier);
> +	int pad;
> +
> +	pad = media_entity_get_fwnode_pad(&subdev->entity, asd->match.fwnode,
> +					  MEDIA_PAD_FL_SOURCE);
> +	if (pad < 0)
> +		return pad;
> +
> +	csi->remote = subdev;
> +	csi->remote_pad = pad;
> +
> +	return media_create_pad_link(&subdev->entity, pad,
> +				     &csi->subdev.entity, 0,
> +				     MEDIA_LNK_FL_ENABLED |
> +				     MEDIA_LNK_FL_IMMUTABLE);
> +}
> +
> +static void mei_csi_notify_unbind(struct v4l2_async_notifier *notifier,
> +				  struct v4l2_subdev *subdev,
> +				  struct v4l2_async_subdev *asd)
> +{
> +	struct mei_csi *csi = notifier_to_csi(notifier);
> +
> +	csi->remote = NULL;
> +}
> +
> +static const struct v4l2_async_notifier_operations mei_csi_notify_ops = {
> +	.bound = mei_csi_notify_bound,
> +	.unbind = mei_csi_notify_unbind,
> +};
> +
> +static int mei_csi_init_control(struct mei_csi *csi)
> +{
> +	v4l2_ctrl_handler_init(&csi->ctrl_handler, 1);
> +	csi->ctrl_handler.lock = &csi->lock;
> +
> +	csi->privacy_ctrl = v4l2_ctrl_new_std(&csi->ctrl_handler, NULL,
> +					      V4L2_CID_PRIVACY, 0, 1, 1, 0);
> +	if (csi->ctrl_handler.error)
> +		return csi->ctrl_handler.error;

The control should be made volatile here (flags |=
V4L2_CTRL_FLAG_READ_ONLY) as it can't be changed by the user.

> +
> +	csi->subdev.ctrl_handler = &csi->ctrl_handler;
> +
> +	return 0;
> +}
> +
> +static int mei_csi_parse_firmware(struct mei_csi *csi)
> +{
> +	struct v4l2_fwnode_endpoint v4l2_ep = {
> +		.bus_type = V4L2_MBUS_CSI2_DPHY,
> +	};
> +	struct device *dev = &csi->cldev->dev;
> +	struct v4l2_async_subdev *asd;
> +	struct fwnode_handle *fwnode;
> +	struct fwnode_handle *ep;
> +	int ret;
> +
> +	ep = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev), 0, 0, 0);
> +	if (!ep) {
> +		dev_err(dev, "not connected to subdevice\n");
> +		return -EINVAL;
> +	}
> +
> +	ret = v4l2_fwnode_endpoint_parse(ep, &v4l2_ep);
> +	if (ret) {
> +		dev_err(dev, "could not parse v4l2 endpoint\n");
> +		fwnode_handle_put(ep);
> +		return -EINVAL;
> +	}
> +
> +	fwnode = fwnode_graph_get_remote_endpoint(ep);
> +	fwnode_handle_put(ep);
> +
> +	v4l2_async_nf_init(&csi->notifier);
> +	csi->notifier.ops = &mei_csi_notify_ops;
> +
> +	asd = v4l2_async_nf_add_fwnode(&csi->notifier, fwnode,
> +				       struct v4l2_async_subdev);
> +	fwnode_handle_put(fwnode);
> +	if (IS_ERR(asd))
> +		return PTR_ERR(asd);
> +
> +	ret = v4l2_async_subdev_nf_register(&csi->subdev, &csi->notifier);
> +	if (ret)
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +
> +	return ret;
> +}
> +
> +static int mei_csi_probe(struct mei_cl_device *cldev,
> +			 const struct mei_cl_device_id *id)
> +{
> +	struct mei_csi *csi;
> +	int ret;
> +
> +	/*
> +	 * no connections to sensor are defined in firmware, try to
> +	 * build connections as software_nodes parsed from SSDB.
> +	 */
> +	ret = csi_bridge_init(cldev);
> +	if (ret)
> +		return ret;
> +
> +	csi = devm_kzalloc(&cldev->dev, sizeof(struct mei_csi), GFP_KERNEL);
> +	if (!csi)
> +		return -ENOMEM;
> +
> +	csi->cldev = cldev;
> +	mutex_init(&csi->lock);
> +	init_completion(&csi->cmd_completion);
> +
> +	mei_cldev_set_drvdata(cldev, csi);
> +
> +	ret = mei_cldev_enable(cldev);
> +	if (ret < 0) {
> +		dev_err(&cldev->dev, "mei_cldev_enable failed: %d\n", ret);
> +		goto destroy_mutex;
> +	}
> +
> +	ret = mei_cldev_register_rx_cb(cldev, mei_csi_rx);
> +	if (ret) {
> +		dev_err(&cldev->dev, "event cb registration failed: %d\n", ret);
> +		goto err_disable;
> +	}
> +
> +	ret = mei_csi_parse_firmware(csi);
> +	if (ret)
> +		goto err_disable;
> +
> +	csi->subdev.dev = &cldev->dev;
> +	v4l2_subdev_init(&csi->subdev, &mei_csi_subdev_ops);
> +	v4l2_set_subdevdata(&csi->subdev, csi);
> +	csi->subdev.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
> +	csi->subdev.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> +	csi->subdev.entity.ops = &mei_csi_entity_ops;
> +
> +	ret = mei_csi_init_control(csi);
> +	if (ret)
> +		goto err_async;

You'll also need to call v4l2_ctrl_handler_free() if setting up the handler
failed. I.e. just change the label here and remove err_async label below.

> +
> +	csi->format_mbus[CSI_PAD_SOURCE] = mei_csi_format_mbus_default;
> +	csi->format_mbus[CSI_PAD_SINK] = mei_csi_format_mbus_default;
> +
> +	csi->pads[CSI_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
> +	csi->pads[CSI_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> +	ret = media_entity_pads_init(&csi->subdev.entity, CSI_NUM_PADS,
> +				     csi->pads);
> +	if (ret)
> +		goto err_ctrl_handler;
> +
> +	ret = v4l2_subdev_init_finalize(&csi->subdev);
> +	if (ret < 0)
> +		goto err_entity;
> +
> +	ret = v4l2_async_register_subdev(&csi->subdev);
> +	if (ret < 0)
> +		goto err_subdev;
> +
> +	pm_runtime_enable(&cldev->dev);
> +
> +	return 0;
> +
> +err_subdev:
> +	v4l2_subdev_cleanup(&csi->subdev);
> +err_entity:
> +	media_entity_cleanup(&csi->subdev.entity);
> +err_ctrl_handler:
> +	v4l2_ctrl_handler_free(&csi->ctrl_handler);
> +err_async:
> +	v4l2_async_nf_unregister(&csi->notifier);
> +	v4l2_async_nf_cleanup(&csi->notifier);
> +err_disable:
> +	mei_cldev_disable(cldev);

It'd be nice to have an additional newline before the label. Elsewhere,
too.

> +destroy_mutex:
> +	mutex_destroy(&csi->lock);
> +
> +	return ret;
> +}
> +
> +static void mei_csi_remove(struct mei_cl_device *cldev)
> +{
> +	struct mei_csi *csi = mei_cldev_get_drvdata(cldev);
> +
> +	v4l2_async_nf_unregister(&csi->notifier);
> +	v4l2_async_nf_cleanup(&csi->notifier);
> +	v4l2_ctrl_handler_free(&csi->ctrl_handler);
> +	v4l2_async_unregister_subdev(&csi->subdev);
> +	v4l2_subdev_cleanup(&csi->subdev);
> +	media_entity_cleanup(&csi->subdev.entity);
> +
> +	pm_runtime_disable(&cldev->dev);
> +
> +	mutex_destroy(&csi->lock);
> +}
> +
> +#define MEI_CSI_UUID UUID_LE(0x92335FCF, 0x3203, 0x4472, \
> +			     0xAF, 0x93, 0x7b, 0x44, 0x53, 0xAC, 0x29, 0xDA)
> +
> +static const struct mei_cl_device_id mei_csi_tbl[] = {
> +	{ MEI_CSI_DRIVER_NAME, MEI_CSI_UUID, MEI_CL_VERSION_ANY },
> +

Extra newline.

> +	/* required last entry */

The comment could be on the same line below. E.g. "Sentinel" is
appropriate, as this isn't just any last entry.

> +	{ }
> +};
> +MODULE_DEVICE_TABLE(mei, mei_csi_tbl);
> +
> +static struct mei_cl_driver mei_csi_driver = {
> +	.id_table = mei_csi_tbl,
> +	.name = MEI_CSI_DRIVER_NAME,
> +
> +	.probe = mei_csi_probe,
> +	.remove = mei_csi_remove,
> +};
> +
> +module_mei_cl_driver(mei_csi_driver);
> +
> +MODULE_AUTHOR("Wentong Wu <wentong.wu@intel.com>");
> +MODULE_AUTHOR("Zhifeng Wang <zhifeng.wang@intel.com>");
> +MODULE_DESCRIPTION("Device driver for IVSC CSI");
> +MODULE_LICENSE("GPL");

-- 
Kind regards,

Sakari Ailus