V4L2驱动框架
主設備號： 81
次設備號：
?? ?0-63
?? ?64-67
?? ?192-223
?? ?224-255
/dev/videoX?? ?
應用層
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char驅動
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V4L2
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具體的驅動
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硬件
應用層的操作都需要有底層V4L2驅動的支持。內核中有一些非常完善的例子。比如：linux-2.6.26內核目錄drivers/media/video/vivi.c中的驅動代碼實例。
1、V4L2驅動注冊、注銷函數
static int __init videodev_init(void)?? ??? ?//注冊256個視頻設備
{
??????? dev_t dev = MKDEV(VIDEO_MAJOR, 0);
??????? int ret;
??????? printk(KERN_INFO "Linux video capture interface: v2.00\n");
??????? ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
??????? if (ret < 0) {
??????????????? printk(KERN_WARNING "videodev: unable to get major %d\n", VIDEO_MAJOR);
??????????????? return ret;
??????? }
??????? ret = class_register(&video_class);
??????? if (ret < 0) {
??????????????? unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
??????????????? printk(KERN_WARNING "video_dev: class_register failed\n");
??????????????? return -EIO;
??????? }
??????? return 0;
}
static void __exit videodev_exit(void)
{
??????? dev_t dev = MKDEV(VIDEO_MAJOR, 0);
??????? class_unregister(&video_class);
??????? unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
}
module_init(videodev_init)
module_exit(videodev_exit)
2、函數實現
2.1
Video核心層（drivers/media/video/videodev.c）提供了注冊函數供具體的V4L2驅動調用:
int video_register_device(struct video_device *vfd, int type, int nr)
?? ?—video_device: 要構建的核心數據結構
?? ?—Type: 表示設備類型，此設備號的基地址受此變量的影響
?? ?—Nr: 如果end-base>nr>0 ：次設備號=base（基準值，受type影響）+nr；否則：系統自動分配合適的次設備號
函數內部調用
static int __video_register_device(struct video_device *vdev, int type, int nr, int warn_if_nr_in_use)
具體驅動只需要構建video_device結構，然后調用注冊函數既可。
2.2
Video核心層（drivers/media/video/videodev.c）提供了注銷函數
void video_unregister_device(struct video_device *vdev)
核心定義設備數組，其中VIDEO_NUM_DEVICES 為 256 是最大設備數
static struct video_device *video_device[VIDEO_NUM_DEVICES];
2.3
V4L2提供了統一的應用層接口
static const struct file_operations v4l2_fops = {
??????? .owner = THIS_MODULE,
??????? .read = v4l2_read,
??????? .write = v4l2_write,
??????? .open = v4l2_open,
??????? .mmap = v4l2_mmap,
??????? .unlocked_ioctl = v4l2_ioctl,
#ifdef CONFIG_COMPAT
??????? .compat_ioctl = v4l2_compat_ioctl32,
#endif
??????? .release = v4l2_release,
??????? .poll = v4l2_poll,
??????? .llseek = no_llseek,
};
v4l2_read定義如下
static ssize_t v4l2_read(struct file *filp, char __user *buf, size_t sz, loff_t *off)
{
??????? struct video_device *vdev = video_devdata(filp);
??????? int ret = -ENODEV;
??????? if (!vdev->fops->read)
??????????????? return -EINVAL;
??????? if (vdev->lock && mutex_lock_interruptible(vdev->lock))
??????????????? return -ERESTARTSYS;
??????? if (video_is_registered(vdev))
??????????????? ret = vdev->fops->read(filp, buf, sz, off);
??????? if (vdev->lock)
??????????????? mutex_unlock(vdev->lock);
??????? return ret;
}
函數內部調用的?? ?vdev->fops->read? 由具體的V4L2驅動實現
驅動開發
定義最重要的數據結構體struct video_device，
其中，重要的是
const struct v4l2_file_operations *fops;??? //幀緩沖操作
編寫幀緩沖驅動的主要工作就是編寫fops各個成員函數
編寫具體驅動方法步驟:
1、構建具體驅動的struct video_device;
3、構建具體驅動的struct fops,并定義相關的操作函數；
4、定義具體驅動的XXX_probe。
struct video_device
{
??????? /* device ops */
??????? const struct v4l2_file_operations *fops;
??????? /* sysfs */
??????? struct device dev;????????????? /* v4l device */
??????? struct cdev *cdev;????????????? /* character device */
??????? /* Set either parent or v4l2_dev if your driver uses v4l2_device */
??????? struct device *parent;????????? /* device parent */
??????? struct v4l2_device *v4l2_dev;?? /* v4l2_device parent */
??????? /* Control handler associated with this device node. May be NULL. */
??????? struct v4l2_ctrl_handler *ctrl_handler;
??????? /* device info */
??????? char name[32];
??????? int vfl_type;
??????? /* 'minor' is set to -1 if the registration failed */
??????? int minor;
??????? u16 num;
??????? /* use bitops to set/clear/test flags */
??????? unsigned long flags;
??????? /* attribute to differentiate multiple indices on one physical device */
??????? int index;
??????? /* V4L2 file handles */
??????? spinlock_t????????????? fh_lock; /* Lock for all v4l2_fhs */
??????? struct list_head??????? fh_list; /* List of struct v4l2_fh */
??????? int debug;????????????????????? /* Activates debug level*/
??????? /* Video standard vars */
??????? v4l2_std_id tvnorms;??????????? /* Supported tv norms */
??????? v4l2_std_id current_norm;?????? /* Current tvnorm */
??????? /* callbacks */
??????? void (*release)(struct video_device *vdev);
??????? /* ioctl callbacks */
??????? const struct v4l2_ioctl_ops *ioctl_ops;
??????? /* serialization lock */
??????? struct mutex *lock;
};
================================================================================
struct v4l2_file_operations {
??????? struct module *owner;
??????? ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
??????? ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
??????? unsigned int (*poll) (struct file *, struct poll_table_struct *);
??????? long (*ioctl) (struct file *, unsigned int, unsigned long);
??????? long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
??????? int (*mmap) (struct file *, struct vm_area_struct *);
??????? int (*open) (struct file *);
??????? int (*release) (struct file *);
};
================================================================================
struct device {
??????? struct device?????????? *parent;
??????? struct device_private?? *p;
??????? struct kobject kobj;
??????? const char????????????? *init_name;/* initial name of the device */
??????? struct device_type????? *type;
??????? struct mutex??????????? mutex; ??? ?/* mutex to synchronize calls to its driver. */
??????? struct bus_type *bus;????????? ??? ?/* type of bus device is on */
??????? struct device_driver ?? ?*driver;?? ?/* which driver has allocated this device */
??????? void?????????? ??? ?*platform_data; /* Platform specific data, device core doesn't touch it */
??????? struct dev_pm_info????? power;
#ifdef CONFIG_NUMA
??????? int??????????? ??? ?numa_node;????? /* NUMA node this device is close to */
#endif
??????? u64??????????? ??? ?*dma_mask;????? /* dma mask (if dma'able device) */
??????? u64??????????? ??? ?coherent_dma_mask;/* Like dma_mask, but for alloc_coherent mappings as not all hardware supports 64 bit ses for consistent allocations such descriptors. */
??????? struct device_dma_parameters *dma_parms;
??????? struct list_head??????? dma_pools;????? /* dma pools (if dma'ble) */
??????? struct dma_coherent_mem *dma_mem; /* internal for coherent mem override */
??????? /* arch specific additions */
??????? struct dev_archdata???? archdata;
#ifdef CONFIG_OF
??????? struct device_node????? *of_node;
#endif
??????? dev_t?????????????????? devt;?? /* dev_t, creates the sysfs "dev" */
??????? spinlock_t????????????? devres_lock;
??????? struct list_head??????? devres_head;
??????? struct klist_node?????? knode_class;
??????? struct class??????????? *class;
??????? const struct attribute_group **groups;? /* optional groups */
??????? void??? (*release)(struct device *dev);
};
================================================================================
struct cdev {
??????? struct kobject kobj;
??????? struct module *owner;
??????? const struct file_operations *ops;
??????? struct list_head list;
??????? dev_t dev;
??????? unsigned int count;
};
================================================================================
struct v4l2_device {
??????? struct device *dev;?? ?/* dev->driver_data points to this struct. Note: dev might be NULL if there is no parent device as is the case with e.g. ISA devices. */
??????? struct list_head subdevs;????????? /* used to keep track of the registered subdevs */
??????? spinlock_t lock;? /* lock this struct; can be used by the driver as well if this struct is embedded into a larger struct. */
??????? char name[V4L2_DEVICE_NAME_SIZE];??????? /* unique device name, by default the driver name + bus ID */
??????? void (*notify)(struct v4l2_subdev *sd, unsigned int notification, void *arg);??????? /* notify callback called by some sub-devices. */
??????? struct v4l2_ctrl_handler *ctrl_handler;??????? /* The control handler. May be NULL. */
??????? struct mutex ioctl_lock;??????? /* BKL replacement mutex. Temporary solution only. */
};
================================================================================
struct v4l2_ioctl_ops {
??????? /* ioctl callbacks */
??????? /* VIDIOC_QUERYCAP handler */
??????? int (*vidioc_querycap)(struct file *file, void *fh, struct v4l2_capability *cap);
??????? /* Priority handling */
??????? int (*vidioc_g_priority)?? (struct file *file, void *fh, enum v4l2_priority *p);
??????? int (*vidioc_s_priority)?? (struct file *file, void *fh, enum v4l2_priority p);
??????? /* VIDIOC_ENUM_FMT handlers */
??????? int (*vidioc_enum_fmt_vid_cap)???? (struct file *file, void *fh, struct v4l2_fmtdesc *f);
??????? int (*vidioc_enum_fmt_vid_overlay) (struct file *file, void *fh, struct v4l2_fmtdesc *f);
??????? int (*vidioc_enum_fmt_vid_out)???? (struct file *file, void *fh, struct v4l2_fmtdesc *f);
??????? int (*vidioc_enum_fmt_type_private)(struct file *file, void *fh, struct v4l2_fmtdesc *f);
??????? /* VIDIOC_G_FMT handlers */
??????? int (*vidioc_g_fmt_vid_cap)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_g_fmt_vid_overlay)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_g_fmt_vid_out)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_g_fmt_vid_out_overlay)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_g_fmt_vbi_cap)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_g_fmt_vbi_out)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_g_fmt_sliced_vbi_cap)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_g_fmt_sliced_vbi_out)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_g_fmt_type_private)(struct file *file, void *fh, struct v4l2_format *f);
??????? /* VIDIOC_S_FMT handlers */
??????? int (*vidioc_s_fmt_vid_cap)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_s_fmt_vid_overlay)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_s_fmt_vid_out)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_s_fmt_vid_out_overlay)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_s_fmt_vbi_cap)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_s_fmt_vbi_out)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_s_fmt_sliced_vbi_cap)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_s_fmt_sliced_vbi_out)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_s_fmt_type_private)(struct file *file, void *fh, struct v4l2_format *f);
??????? /* VIDIOC_TRY_FMT handlers */
??????? int (*vidioc_try_fmt_vid_cap)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_try_fmt_vid_overlay)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_try_fmt_vid_out)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_try_fmt_vid_out_overlay)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_try_fmt_vbi_cap)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_try_fmt_vbi_out)??? (struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_try_fmt_sliced_vbi_cap)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_try_fmt_sliced_vbi_out)(struct file *file, void *fh, struct v4l2_format *f);
??????? int (*vidioc_try_fmt_type_private)(struct file *file, void *fh, struct v4l2_format *f);
??????? /* Buffer handlers */
??????? int (*vidioc_reqbufs) (struct file *file, void *fh, struct v4l2_requestbuffers *b);
??????? int (*vidioc_querybuf)(struct file *file, void *fh, struct v4l2_buffer *b);
??????? int (*vidioc_qbuf)??? (struct file *file, void *fh, struct v4l2_buffer *b);
??????? int (*vidioc_dqbuf)?? (struct file *file, void *fh, struct v4l2_buffer *b);
??????? int (*vidioc_overlay)?? ?(struct file *file, void *fh, unsigned int i);
??????? int (*vidioc_g_fbuf)?? ?(struct file *file, void *fh, struct v4l2_framebuffer *a);
??????? int (*vidioc_s_fbuf)?? ?(struct file *file, void *fh, struct v4l2_framebuffer *a);
??????? /* Stream on/off */
??????? int (*vidioc_streamon)?? ?(struct file *file, void *fh, enum v4l2_buf_type i);
??????? int (*vidioc_streamoff)?? ?(struct file *file, void *fh, enum v4l2_buf_type i);
??????? /* Standard handling ENUMSTD is handled by videodev.c */
??????? int (*vidioc_g_std) ?? ?(struct file *file, void *fh, v4l2_std_id *norm);
??????? int (*vidioc_s_std) ?? ?(struct file *file, void *fh, v4l2_std_id *norm);
??????? int (*vidioc_querystd) ?? ?(struct file *file, void *fh, v4l2_std_id *a);
??????? /* Input handling */
??????? int (*vidioc_enum_input)?? ?(struct file *file, void *fh, struct v4l2_input *inp);
??????? int (*vidioc_g_input)? ??? ?(struct file *file, void *fh, unsigned int *i);
??????? int (*vidioc_s_input)? ??? ?(struct file *file, void *fh, unsigned int i);
??????? /* Output handling */
??????? int (*vidioc_enum_output)?? ?(struct file *file, void *fh, struct v4l2_output *a);
??????? int (*vidioc_g_output)? ??? ?(struct file *file, void *fh, unsigned int *i);
??????? int (*vidioc_s_output)? ??? ?(struct file *file, void *fh, unsigned int i);
??????? /* Control handling */
??????? int (*vidioc_queryctrl)??????? (struct file *file, void *fh, struct v4l2_queryctrl *a);
??????? int (*vidioc_g_ctrl)?????????? (struct file *file, void *fh, struct v4l2_control *a);
??????? int (*vidioc_s_ctrl)?????????? (struct file *file, void *fh, struct v4l2_control *a);
??????? int (*vidioc_g_ext_ctrls)????? (struct file *file, void *fh, struct v4l2_ext_controls *a);
??????? int (*vidioc_s_ext_ctrls)????? (struct file *file, void *fh, struct v4l2_ext_controls *a);
??????? int (*vidioc_try_ext_ctrls)??? (struct file *file, void *fh, struct v4l2_ext_controls *a);
??????? int (*vidioc_querymenu)??????? (struct file *file, void *fh, struct v4l2_querymenu *a);
??????? /* Audio ioctls */
??????? int (*vidioc_enumaudio)??????? (struct file *file, void *fh, struct v4l2_audio *a);
??????? int (*vidioc_g_audio)????????? (struct file *file, void *fh, struct v4l2_audio *a);
??????? int (*vidioc_s_audio)????????? (struct file *file, void *fh, struct v4l2_audio *a);
??????? /* Audio out ioctls */
??????? int (*vidioc_enumaudout)?????? (struct file *file, void *fh, struct v4l2_audioout *a);
??????? int (*vidioc_g_audout)???????? (struct file *file, void *fh, struct v4l2_audioout *a);
??????? int (*vidioc_s_audout)???????? (struct file *file, void *fh, struct v4l2_audioout *a);
??????? int (*vidioc_g_modulator)????? (struct file *file, void *fh, struct v4l2_modulator *a);
??????? int (*vidioc_s_modulator)????? (struct file *file, void *fh, struct v4l2_modulator *a);
??????? /* Crop ioctls */
??????? int (*vidioc_cropcap)????????? (struct file *file, void *fh, struct v4l2_cropcap *a);
??????? int (*vidioc_g_crop)?????????? (struct file *file, void *fh, struct v4l2_crop *a);
??????? int (*vidioc_s_crop)?????????? (struct file *file, void *fh, struct v4l2_crop *a);
??????? /* Compression ioctls */
??????? int (*vidioc_g_jpegcomp)?????? (struct file *file, void *fh, struct v4l2_jpegcompression *a);
??????? int (*vidioc_s_jpegcomp)?????? (struct file *file, void *fh, struct v4l2_jpegcompression *a);
??????? int (*vidioc_g_enc_index)????? (struct file *file, void *fh, struct v4l2_enc_idx *a);
??????? int (*vidioc_encoder_cmd)????? (struct file *file, void *fh, struct v4l2_encoder_cmd *a);
??????? int (*vidioc_try_encoder_cmd)? (struct file *file, void *fh, struct v4l2_encoder_cmd *a);
??????? /* Stream type-dependent parameter ioctls */
??????? int (*vidioc_g_parm)?????????? (struct file *file, void *fh, struct v4l2_streamparm *a);
??????? int (*vidioc_s_parm)?????????? (struct file *file, void *fh, struct v4l2_streamparm *a);
??????? /* Tuner ioctls */
??????? int (*vidioc_g_tuner)????????? (struct file *file, void *fh, struct v4l2_tuner *a);
??????? int (*vidioc_s_tuner)????????? (struct file *file, void *fh, struct v4l2_tuner *a);
??????? int (*vidioc_g_frequency)????? (struct file *file, void *fh, struct v4l2_frequency *a);
??????? int (*vidioc_s_frequency)????? (struct file *file, void *fh, struct v4l2_frequency *a);
??????? /* Sliced VBI cap */
??????? int (*vidioc_g_sliced_vbi_cap) (struct file *file, void *fh, struct v4l2_sliced_vbi_cap *a);
??????? /* Log status ioctl */
??????? int (*vidioc_log_status)?????? (struct file *file, void *fh);
??????? int (*vidioc_s_hw_freq_seek)?? (struct file *file, void *fh, struct v4l2_hw_freq_seek *a);
??????? /* Debugging ioctls */
#ifdef CONFIG_VIDEO_ADV_DEBUG
??????? int (*vidioc_g_register)?????? (struct file *file, void *fh, struct v4l2_dbg_register *reg);
??????? int (*vidioc_s_register)?????? (struct file *file, void *fh, struct v4l2_dbg_register *reg);
#endif
??????? int (*vidioc_g_chip_ident)?? ??? (struct file *file, void *fh, struct v4l2_dbg_chip_ident *chip);
??????? int (*vidioc_enum_framesizes)????? (struct file *file, void *fh, struct v4l2_frmsizeenum *fsize);
??????? int (*vidioc_enum_frameintervals)? (struct file *file, void *fh, struct v4l2_frmivalenum *fival);
??????? /* DV Timings IOCTLs */
??????? int (*vidioc_enum_dv_presets)? (struct file *file, void *fh, struct v4l2_dv_enum_preset *preset);
??????? int (*vidioc_s_dv_preset)????? (struct file *file, void *fh, struct v4l2_dv_preset *preset);
??????? int (*vidioc_g_dv_preset)????? (struct file *file, void *fh, struct v4l2_dv_preset *preset);
??????? int (*vidioc_query_dv_preset)? (struct file *file, void *fh, struct v4l2_dv_preset *qpreset);
??????? int (*vidioc_s_dv_timings)???? (struct file *file, void *fh, struct v4l2_dv_timings *timings);
??????? int (*vidioc_g_dv_timings)???? (struct file *file, void *fh, struct v4l2_dv_timings *timings);
??????? int (*vidioc_subscribe_event)? (struct v4l2_fh *fh, struct v4l2_event_subscription *sub);
??????? int (*vidioc_unsubscribe_event)(struct v4l2_fh *fh, struct v4l2_event_subscription *sub);
??????? /* For other private ioctls */
??????? long (*vidioc_default)???????? (struct file *file, void *fh, int cmd, void *arg);
};
================================================================================
================================================================================
================================================================================
static struct ov7670_format_struct {
??????? enum v4l2_mbus_pixelcode mbus_code;
??????? enum v4l2_colorspace colorspace;
??????? struct regval_list *regs;
??????? int cmatrix[CMATRIX_LEN];
?? ?int bpp;
} ov7670_format_struct ov7670_formats[] = {
?? ?/* "YUYV 4:2:2"???? */
?? ??? ?.desc?? ??? ?= "YUYV 4:2:2",
?? ??? ?.pixelformat?? ?= V4L2_PIX_FMT_YUYV,
?? ??? ?.regs ?? ??? ?= ov7670_fmt_yuv422,
?? ??? ?.cmatrix?? ?= { 128, -128, 0, -34, -94, 128 },
?? ??? ?.bpp?? ??? ?= 2,
?? ?/* "UYVY 4:2:2"???? */
?? ?/* "RGB 444"??????? */
?? ?/* "RGB 565"??????? */
?? ?/* "Raw RGB Bayer"? */
}
#define N_OV7670_FMTS ARRAY_SIZE(ov7670_formats)
struct v4l2_fmtdesc {
??????? __u32?????????????? index;???????????? /* Format number????? */
??????? enum v4l2_buf_type? type;????????????? /* buffer type??????? */
??????? __u32?????????????? flags;
??????? __u8??????????????? description[32];?? /* Description string */
??????? __u32?????????????? pixelformat;?????? /* Format fourcc????? */
??????? __u32?????????????? reserved[4];
};
?
//每一個subdev驅動程序實例應該創建這個結構，無論是獨立或在一個更大的結構之中。
struct v4l2_subdev {
??????? struct list_head list;
??????? struct module *owner;
??????? u32 flags;
??????? struct v4l2_device *v4l2_dev;
??????? const struct v4l2_subdev_ops *ops;
??????? /* name must be unique */
??????? char name[V4L2_SUBDEV_NAME_SIZE];
??????? /* can be used to group similar subdevs, value is driver-specific */
??????? u32 grp_id;?
??????? /* pointer to private data */
??????? void *priv;
};?
struct v4l2_pix_format {?
??????? __u32?????????????????? width;
??????? __u32?????????????????? height;
??????? __u32?????????????????? pixelformat;
??????? enum v4l2_field???????? field;
??????? __u32?????????????????? bytesperline;?? /* for padding, zero if unused */
??????? __u32?????????????????? sizeimage;
??????? enum v4l2_colorspace??? colorspace;
??????? __u32?????????????????? priv;?????????? /* private data, depends on pixelformat */
}; ?
struct v4l2_format {?
??????? enum v4l2_buf_type type;
??????? union {?
??????????????? struct v4l2_pix_format????????? pix;???? /* V4L2_BUF_TYPE_VIDEO_CAPTURE */
??????????????? struct v4l2_window????????????? win;???? /* V4L2_BUF_TYPE_VIDEO_OVERLAY */
??????????????? struct v4l2_vbi_format????????? vbi;???? /* V4L2_BUF_TYPE_VBI_CAPTURE */
??????????????? struct v4l2_sliced_vbi_format?? sliced;? /* V4L2_BUF_TYPE_SLICED_VBI_CAPTURE */
??????????????? __u8??? raw_data[200];?????????????????? /* user-defined */
??????? } fmt;
};
static struct ov7670_win_size {
??????? int???? width;
??????? int???? height;
??????? unsigned char com7_bit;
??????? int???? hstart;???????? /* Start/stop values for the camera.? Note */
??????? int???? hstop;????????? /* that they do not always make complete */
??????? int???? vstart;???????? /* sense to humans, but evidently the sensor */
??????? int???? vstop;????????? /* will do the right thing... */
??????? struct regval_list *regs; /* Regs to tweak */
?? ??? ??? ??? ?/* h/vref stuff */
} ov7670_win_sizes[] = {
?? ?/* VGA */
?? ?/* CIF */
?? ?/* QVGA */
?? ?/* QCIF */
}
#define N_WIN_SIZES (ARRAY_SIZE(ov7670_win_sizes))
總結
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