ioctls

根据 determine_valid_ioctls() 函数，video rx 设备支持的 ioctl 有：

VIDIOC_QUERYCAP // 要定义 ops->vidioc_querycap
VIDIOC_G_PRIORITY
VIDIOC_S_PRIORITY
VIDIOC_G_FREQUENCY // ops->vidioc_g_frequency
VIDIOC_S_FREQUENCY // ops->vidioc_s_frequency
VIDIOC_LOG_STATUS // ops->vidioc_log_status
VIDIOC_DQEVENT // ops->vidioc_subscribe_event
VIDIOC_SUBSCRIBE_EVENT // ops->vidioc_subscribe_event
VIDIOC_UNSUBSCRIBE_EVENT // ops->vidioc_unsubscribe_event

在定义了 vdev->ctrl_handler 的情况下：

VIDIOC_QUERYCTRL // ops->vidioc_queryctrl
VIDIOC_QUERY_EXT_CTRL // ops->vidioc_query_ext_ctrl
VIDIOC_G_CTRL // ops->vidioc_g_ctrl || ops->vidioc_g_ext_ctrls
VIDIOC_S_CTRL // ops->vidioc_s_ctrl || ops->vidioc_s_ext_ctrls
VIDIOC_G_EXT_CTRLS // ops->vidioc_g_ext_ctrls
VIDIOC_S_EXT_CTRLS // ops->vidioc_s_ext_ctrls
VIDIOC_TRY_EXT_CTRLS // ops->vidioc_try_ext_ctrls
VIDIOC_QUERYMENU // ops->vidioc_querymenu

VIDIOC_ENUM_FMT // ops->vidioc_enum_fmt_vid_cap || ops->vidioc_enum_fmt_vid_overlay
VIDIOC_G_FMT // vidioc_g_fmt_vid_cap || vidioc_g_fmt_vid_cap_mplane || vidioc_g_fmt_vid_overlay
VIDIOC_S_FMT // 同上
VIDIOC_TRY_FMT // 同上
VIDIOC_OVERLAY
VIDIOC_G_FBUF
VIDIOC_S_FBUF
VIDIOC_G_JPEGCOMP
VIDIOC_S_JPEGCOMP
VIDIOC_G_ENC_INDEX
VIDIOC_ENCODER_CMD
VIDIOC_TRY_ENCODER_CMD
VIDIOC_DECODER_CMD
VIDIOC_TRY_DECODER_CMD
VIDIOC_ENUM_FRAMESIZES
VIDIOC_ENUM_FRAMEINTERVALS
VIDIOC_G_CROP // vidioc_g_selection
VIDIOC_CROPCAP // // vidioc_g_selection
VIDIOC_S_CROP // vidioc_s_selection
VIDIOC_G_SELECTION
VIDIOC_S_SELECTION

VIDIOC_REQBUFS
VIDIOC_QUERYBUF
VIDIOC_QBUF
VIDIOC_EXPBUF
VIDIOC_DQBUF
VIDIOC_CREATE_BUFS
VIDIOC_PREPARE_BUF
VIDIOC_STREAMON
VIDIOC_STREAMOFF

VIDIOC_ENUMSTD
VIDIOC_S_STD
VIDIOC_G_STD
VIDIOC_QUERYSTD

Video for Linux API

static void rtsisp_hw_free_vreg(struct rtsisp_dev_info *dev_info)
{
	struct rtsisp_hw *hw = dev_info->hw;
	struct rtsisp_dev_hw_info *hw_info = &hw->hw_info[dev_info->dev_id];

	if (hw_info->vregs) {
		vfree(hw_info->vregs);
		hw_info->vregs = NULL;
	}

	if (hw->dev_num == 1 && hw->vregs_bitmap) {
		bitmap_free(hw->vregs_bitmap);
		hw->vregs_bitmap = NULL;
	}
}

1.2 Querying Capabilities

查询 v4l2 设备支持的功能，返回 struct v4l2_capability 结构体。所有 app 程序在 open 后都要执行。

struct v4l2_capability caps;
ioctl(fd, VIDIOC_QUERYCAP, &caps);

struct v4l2_capability {
	__u8	driver[16];
	__u8	card[32];
	__u8	bus_info[32];
	__u32   version;
	__u32	capabilities;
	__u32	device_caps;
	__u32	reserved[3];
};

driver: 驱动名称。 card: 设备名称。 bus_info: bus 名称，比如 platform:xxx
version: kernel 版本。 capabilities: 物理设备支持的功能。看着和 device_caps 差不多，多一个 V4L2_CAP_DEVICE_CAPS?
device_caps: 设备支持的功能。

1.3 Application Priority

1.4 Video Inputs and Outputs

struct v4l2_input input;
ioctl(fd, VIDIOC_G_INPUT, &index); // 获取 input index
ioctl(fd, VIDIOC_G_OUTPUT, &index); // 获取 output index
ioctl(fd, VIDIOC_S_INPUT, &index); // 选择 input index
ioctl(fd, VIDIOC_S_OUTPUT, &index); // 选择 output index
ioctl(fd, VIDIOC_ENUMINPUT, &input); // 传入 input.index, 获取第 index 个 input 的信息
ioctl(fd, VIDIOC_ENUMOUTPUT, &output); // 传入 output.index, 获取第 index 个 output 的信息

对于 media controller, input/ouput 另外控制，这里只会有一个 input 和 output.

1.5 Audio Inputs and Outputs

audio 相关

1.6 Tuners and Modulators

调谐器，调制器。

1.7 Video Standards

tv 相关

1.8 Digital Video (DV) Timings

tv 相关。

1.9 User Controls

7.14 ioctl VIDIOC_ENUM_FMT

Enumerate image formats.

app 初始化 struct v4l2_fmtdesc 结构体，传入 type, mbus_code, index, 其他由内核填充并返回。

struct v4l2_fmtdesc {
	__u32		    index;             /* Format number      */
	__u32		    type;              /* enum v4l2_buf_type */
	__u32               flags;
	__u8		    description[32];   /* Description string */
	__u32		    pixelformat;       /* Format fourcc      */
	__u32		    mbus_code;		/* Media bus code    */
	__u32		    reserved[3];
};

index: app 要查询的 format index.
type: capture 设备传 V4L2_BUF_TYPE_VIDEO_CAPTURE/V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE.
flags:
description: drvier 返回的 format 的 description.
pixelformat: driver 返回的 format(fourcc code).
mbus_code: app 传入的 mbus_code, 可以来索引不同的 mbus 的 format.

7.25 ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL

get or set the value of control.

app 传入标准的 v4l2_ctrl id, driver 返回 value.

v4l2_ctrl id 参考 v4l2-controls.h.

struct v4l2_control {
	__u32		     id;
	__s32		     value;
};

7.29 ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS

Get or set the value of several controls, try control values.

int ioctl(int fd, VIDIOC_G_EXT_CTRLS, struct v4l2_ext_controls *argp);
int ioctl(int fd, VIDIOC_S_EXT_CTRLS, struct v4l2_ext_controls *argp);
int ioctl(int fd, VIDIOC_TRY_EXT_CTRLS, struct v4l2_ext_controls *argp);

app 传入 count, which, controls, reserved, 并且初始化好所有的 v4l2_ext_control.

struct v4l2_ext_controls {
	union {
#ifndef __KERNEL__
		__u32 ctrl_class;
#endif
		__u32 which;
	};
	__u32 count;
	__u32 error_idx;
	__s32 request_fd;
	__u32 reserved[1];
	struct v4l2_ext_control *controls;
};

ctrl_class: 已废弃，使用 which.
which: V4L2_CTRL_WHICH_CUR_VAL/V4L2_CTRL_WHICH_DEF_VAL/V4L2_CTRL_WHICH_REQUEST_VAL.
count: controls 数组的数量。 error_idx: driver 返回发生错误的 control index.
request_fd:
reserved[1]: 设置为 0.
controls: control 数组。

struct v4l2_ext_control {
	__u32 id;
	__u32 size;
	__u32 reserved2[1];
	union {
		__s32 value;
		__s64 value64;
		char __user *string;
		__u8 __user *p_u8;
		__u16 __user *p_u16;
		__u32 __user *p_u32;
		__s32 __user *p_s32;
		__s64 __user *p_s64;
		// ...
		void __user *ptr;
	};
}

id: control id.
size: 通常为 0, 对于 pointer control 要设置为发送或接收的 payload 大小。 reserved2: 设置为 0.
value: 要设置的 control value.

7.31 ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT

Get or set the data format, try a format.

struct v4l2_format {
	__u32	 type;
	union {
		struct v4l2_pix_format		pix;     /* V4L2_BUF_TYPE_VIDEO_CAPTURE */
		struct v4l2_pix_format_mplane	pix_mp;  /* V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE */
		// ... other types format
	} fmt;
};

struct v4l2_pix_format {
	__u32			width;
	__u32			height;
	__u32			pixelformat;
	__u32			field;		/* enum v4l2_field */
	__u32			bytesperline;	/* for padding, zero if unused */
	__u32			sizeimage;
	__u32			colorspace;	/* enum v4l2_colorspace */
	__u32			priv;		/* private data, depends on pixelformat */
	__u32			flags;		/* format flags (V4L2_PIX_FMT_FLAG_*) */
	union {
		__u32			ycbcr_enc;
		__u32			hsv_enc;
	};
	__u32			quantization;	/* enum v4l2_quantization */
	__u32			xfer_func;	/* enum v4l2_xfer_func */
};

width: picture width in pixels.
height: picture height in pixels. 如果 field 是 V4L2_FIELD_TOP/BOTTOM/ALTERNATE, 则 height 代表 field 中的 height pixels, 否则是 frame 中的 height pixels.
pixelformat: picture format in fourcc code.
field: enum v4l2_field 场的类型。 bytesperline: 每行的字节数。 sizeimage: 图像总字节数。 colorspace: enum v4l2_colorspace.
priv: app 设置为 V4L2_PIX_FMT_PRIV_MAGIC, 那么后面的 extended fields 才会有效。 flags: 有 V4L2_PIX_FMT_FLAG_PREMUL_ALPHA 和 V4L2_PIX_FMT_FLAG_SET_CSC.
ycbcr_enc: enum v4l2_ycbcr_encoding.
hsv_enc: enum v4l2_hsv_encoding.
quantization: enum v4l2_quantization.
xfer_func: enum v4l2_xfer_func.

struct v4l2_pix_format_mplane {
	__u32				width;
	__u32				height;
	__u32				pixelformat;
	__u32				field;
	__u32				colorspace;

	struct v4l2_plane_pix_format	plane_fmt[VIDEO_MAX_PLANES];
	__u8				num_planes;
	__u8				flags;
	 union {
		__u8				ycbcr_enc;
		__u8				hsv_enc;
	};
	__u8				quantization;
	__u8				xfer_func;
	__u8				reserved[7];
}

VIDIOC_G_FMT: 获取当前的 format.

VIDIOC_S_FMT: app 设置好所有 field.

VIDIOC_TRY_FMT: 和 VIDIOC_S_FMT 类似，但是 driver 永远不会返回 EBUSY, 不推荐实现。

7.46 ioctl VIDIOC_QBUF, VIDIOC_DQBUF

Exchange a buffer with the driver.

7.47 ioctl VIDIOC_QUERYBUF

Query the status of a buffer.

填充 struct v4l2_buffer 结构体。

struct v4l2_buffer {
	__u32			index;
	__u32			type; // enum v4l2_buf_type
	__u32			bytesused;
	__u32			flags;
	__u32			field;
#ifdef __KERNEL__
	struct __kernel_v4l2_timeval timestamp;
#else
	struct timeval		timestamp;
#endif
	struct v4l2_timecode	timecode;
	__u32			sequence;

	__u32			memory;
	union {
		__u32           offset;
		unsigned long   userptr;
		struct v4l2_plane *planes;
		__s32		fd;
	} m;
	__u32			length;
	__u32			reserved2;
	union {
		__s32		request_fd;
		__u32		reserved;
	};
};

index: buffer index.

7.49 ioctls VIDIOC_QUERYCTRL, VIDIOC_QUERY_EXT_CTRL and VIDIOC_QUERYMENU

Enumerate controls and menu control items.

int ioctl(int fd, VIDIOC_QUERYCTRL, struct v4l2_queryctrl *argp);
int ioctl(int fd, VIDIOC_QUERY_EXT_CTRL, struct v4l2_query_ext_ctrl *argp);
int ioctl(int fd, VIDIOC_QUERYMENU, struct v4l2_querymenu *argp);

struct v4l2_queryctrl {
	__u32		     id;
	__u32		     type;	/* enum v4l2_ctrl_type */
	__u8		     name[32];	/* Whatever */
	__s32		     minimum;	/* Note signedness */
	__s32		     maximum;
	__s32		     step;
	__s32		     default_value;
	__u32                flags;
	__u32		     reserved[2];
};

id: control id. app 设置。 type: enum v4l2_ctrl_type. driver 返回。 name: minimum: maximum: step: default_value: flags: control flags. driver 返回。

struct v4l2_querymenu {
	__u32		id;
	__u32		index;
	union {
		__u8	name[32];	/* Whatever */
		__s64	value;
	};
	__u32		reserved;
}

id: control id, app 设定。 index: 该 menu 选项中的第 index 个，app 设定。 name: driver 返回的 menu control string, V4L2_CTRL_TYPE_MENU 类型 control 适用。 value: driver 返回的 menu control value, V4L2_CTRL_TYPE_INTEGER_MENU 类型 control 适用。

7.52 ioctl VIDIOC_REQBUFS

Initiate Memory Mapping, User Pointer I/O or DMA buffer I/O.

struct v4l2_requestbuffers {
	__u32			count;
	__u32			type;		/* enum v4l2_buf_type */
	__u32			memory;		/* enum v4l2_memory */
	__u32			capabilities;
	__u8			flags;
	__u8			reserved[3];
};

count: app 传入要 request 的 buf 数量，driver 返回实际的 buf 数量。 type: app 传入的 v4l2_buf_type. memory: usersapce 设置为 V4L2_MEMORY_MMAP/V4L2_MEMORY_DMABUF/V4L2_MEMORY_USERPTR. capabilities: driver 返回的 capabilities. flags:

Media Controller API