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:
7.57 ioctl VIDIOC_SUBDEV_ENUM_FRAME_SIZE
struct v4l2_subdev_frame_size_enum {
__u32 index;
__u32 pad;
__u32 code;
__u32 min_width;
__u32 max_width;
__u32 min_height;
__u32 max_height;
__u32 which;
__u32 stream;
__u32 reserved[7];
};
app:
index: 要 get 的 frame size index.pad: pad id.code: bus format code.which: 见 7.60 的 which.
kernel:
min_width, max_width, min_height, max_height: disCrete frame size
的 min 和 max 值相同。
7.58 ioctl VIDIOC_SUBDEV_ENUM_MBUS_CODE
Enumerate media bus formats.
struct v4l2_subdev_mbus_code_enum {
__u32 pad;
__u32 index;
__u32 code;
__u32 which;
__u32 reserved[8];
}
app:
pad: pad id.index: 要 get 的 mbus code index.which: 见 7.60 的 which.
kernel:
code: 返回 bus format, MEDIA_BUS_FMT_XXX.
7.60 ioctl VIDIOC_SUBDEV_G_FMT, VIDIOC_SUBDEV_S_FMT
Get or set the data format on a subdev pad.
struct v4l2_subdev_format {
__u32 which;
__u32 pad;
struct v4l2_mbus_framefmt format;
__u32 reserved[8];
};
struct v4l2_mbus_framefmt {
__u32 width;
__u32 height;
__u32 code;
__u32 field;
__u32 colorspace;
union {
/* enum v4l2_ycbcr_encoding */
__u16 ycbcr_enc;
/* enum v4l2_hsv_encoding */
__u16 hsv_enc;
};
__u16 quantization;
__u16 xfer_func;
__u16 flags;
__u16 reserved[10];
};
VIDIOC_SUBDEV_S_FMT：
app：
which: Format to modified, 传入 enum v4l2_subdev_format_whence,
有 V4L2_SUBDEV_FORMAT_TRY 和 V4L2_SUBDEV_FORMAT_ACTIVE 两个值。前者用来 try format,
后者 apply to hardware.pad: pad id.format: 要设置的 struct v4l2_mbus_framefmt.
7.61 ioctl VIDIOC_SUBDEV_G_FRAME_INTERVAL, VIDIOC_SUBDEV_S_FRAME_INTERVAL
Get or set the frame interval on a subdev pad
struct v4l2_subdev_frame_interval {
__u32 pad;
struct v4l2_fract interval;
__u32 stream;
__u32 reserved[8];
};
struct v4l2_fract {
__u32 numerator;
__u32 denominator;
};
app:
pad: pad number.interval: 要设置的 struct v4l2_fract.stream: stream identifier.
7.66 ioctl VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT
Subscribe or unsubscribe event
struct v4l2_event_subscription {
__u32 type;
__u32 id;
__u32 flags;
__u32 reserved[5];
};
type: 要订阅的 event 类型，V4L2_EVENT_XXX.
id: 根据 type 不同类型，有的需要 event source id.
flags: V4L2_EVENT_SUB_FL_XXX.