USB摄像头驱动之实现数据传输3_设置参数
1、启动传输
/* A11 启动传输
* 参考: uvc_video_enable(video, 1):
* uvc_commit_video
* uvc_init_video
*/
static int myuvc_vidioc_streamon(struct file *file, void *priv, enum v4l2_buf_type i)
{
int ret;
/* 1. 向USB摄像头设置参数: 比如使用哪个format,使用这个format下的哪个frame(分辨率)
* 参考uvc_set_video_ctrl / uvc_get_video_ctrl
* 1.1 根据uvc_streaming_control结构体设置数据包:可以手工设置，也可以读出后设置
* 1.2 调用usb_control_msg函数发出数据包
*/
/* a. 测试参数 */
发参数给USB设备，如果USB设备能够接收这个参数，会保存起来并做一些修正，我们try后只发出（设置）几个参数，很多其他参数并没有设置，如果发出的几个参数合适就把其他参数补齐
ret = myuvc_try_streaming_params(&myuvc_params);
printk("myuvc_try_streaming_params ret = %d\n", ret);
/* b. 取出参数 */
把补齐的所有参数都读取回来
ret = myuvc_get_streaming_params(&myuvc_params);
printk("myuvc_get_streaming_params ret = %d\n", ret);
/* c. 设置参数 */
ret = myuvc_set_streaming_params(&myuvc_params);
printk("myuvc_set_streaming_params ret = %d\n", ret);
myuvc_print_streaming_params(&myuvc_params);
/* d. 设置VideoStreaming Interface所使用的setting
* d.1 从myuvc_params确定带宽
* d.2 根据setting的endpoint能传输的wMaxPacketSize
* 找到能满足该带宽的setting
*/
/* 手工确定:
* bandwidth = myuvc_params.dwMaxPayloadTransferSize = 1024
* 观察lsusb -v -d 0x1e4e:的结果:
* wMaxPacketSize 0x0400 1x 1024 bytes
* bAlternateSetting 8
*/
usb_set_interface(myuvc_udev, myuvc_streaming_intf, myuvc_streaming_bAlternateSetting);
/* 2. 分配一个URB */
ret = myuvc_alloc_init_urbs();
if (ret)
printk("myuvc_alloc_init_urbs err : ret = %d\n", ret);
/* 3. 提交URB以接收数据 */
for (i = 0; i < MYUVC_URBS; ++i) {
if ((ret = usb_submit_urb(myuvc_queue.urb[i], GFP_KERNEL)) < 0) {
printk("Failed to submit URB %u (%d).\n", i, ret);
myuvc_uninit_urbs();
return ret;
}
}
return 0;
}
/* A13 APP通过poll/select函数确定了有数据，就把缓存从队列中取出
* 参考: uvc_dequeue_buffer
*/
static int myuvc_vidioc_dqbuf(struct file *file, void *priv, struct v4l2_buffer *v4l2_buf)
{
/* APP发现数据就绪后, 从mainqueue里取出这个buffer */
struct myuvc_buffer *buf;
int ret = 0;
if (list_empty(&myuvc_queue.mainqueue)) {//队列非空
ret = -EINVAL;
goto done;
}
buf = list_first_entry(&myuvc_queue.mainqueue, struct myuvc_buffer, stream);//取出第1个buffer
switch (buf->state) {
case VIDEOBUF_ERROR:
ret = -EIO;
case VIDEOBUF_DONE:
buf->state = VIDEOBUF_IDLE;
break;
case VIDEOBUF_IDLE:
case VIDEOBUF_QUEUED:
case VIDEOBUF_ACTIVE:
default:
ret = -EINVAL;
goto done;
}
list_del(&buf->stream);//删除第1个buf
done:
return ret;
}
myuvc_udev-》设备，myuvc_streaming_intf-》视频流接口，myuvc_streaming_bAlternateSetting-》设置
usb_set_interface(myuvc_udev, myuvc_streaming_intf, myuvc_streaming_bAlternateSetting);
struct myuvc_streaming_control {
__u16 bmHint; //参考UVC 1.5 Class specification.pdf，每1位都有含义
__u8 bFormatIndex;
__u8 bFrameIndex;
__u32 dwFrameInterval;
__u16 wKeyFrameRate;
__u16 wPFrameRate;
__u16 wCompQuality;
__u16 wCompWindowSize;
__u16 wDelay;
__u32 dwMaxVideoFrameSize;
__u32 dwMaxPayloadTransferSize;
__u32 dwClockFrequency;
__u8 bmFramingInfo;
__u8 bPreferedVersion;
__u8 bMinVersion;
__u8 bMaxVersion;
};
2、测试参数
static int myuvc_try_streaming_params(struct myuvc_streaming_control *ctrl)
{
__u8 *data;
__u16 size;
int ret;
__u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
unsigned int pipe;
memset(ctrl, 0, sizeof *ctrl);
ctrl->bmHint = 1;/* dwFrameInterval */表示在协商（设置参数要发给摄像头看能否备用，不能用修改后重发）过程中，保持帧间隔不变，
ctrl->bFormatIndex = 1;//支持的格式数
ctrl->bFrameIndex = frame_idx + 1;//支持格式下的分辨率数
ctrl->dwFrameInterval = 333333;//帧的间隔(单位是100ns),1秒钟的帧数（30帧）
看文件USB_Video_Payload_Uncompressed_1.5.pdf
在这里插入图片描述
size = uvc_version >= 0x0110 ? 34 : 26;//根据不同版本看需要发送多少数据，利用lsusb中查找bcduvc,也可以在UVC 1.5 Class specification.pdf中查找bcduvc属于哪一个描述符
//分配data
data = kzalloc(size, GFP_KERNEL);//分配缓冲区，
GFP_KERNEL是内核内存分配时最常用的，无内存可用时可引起休眠。
if (data == NULL)
return -ENOMEM;
//用参数填充缓冲区
*(__le16 *)&data[0] = cpu_to_le16(ctrl->bmHint);
data[2] = ctrl->bFormatIndex;
data[3] = ctrl->bFrameIndex;
*(__le32 *)&data[4] = cpu_to_le32(ctrl->dwFrameInterval);
*(__le16 *)&data[8] = cpu_to_le16(ctrl->wKeyFrameRate);
*(__le16 *)&data[10] = cpu_to_le16(ctrl->wPFrameRate);
*(__le16 *)&data[12] = cpu_to_le16(ctrl->wCompQuality);
*(__le16 *)&data[14] = cpu_to_le16(ctrl->wCompWindowSize);
*(__le16 *)&data[16] = cpu_to_le16(ctrl->wDelay);
put_unaligned_le32(ctrl->dwMaxVideoFrameSize, &data[18]);
put_unaligned_le32(ctrl->dwMaxPayloadTransferSize, &data[22]);
if (size == 34) {
put_unaligned_le32(ctrl->dwClockFrequency, &data[26]);
data[30] = ctrl->bmFramingInfo;
data[31] = ctrl->bPreferedVersion;
data[32] = ctrl->bMinVersion;
data[33] = ctrl->bMaxVersion;
}
pipe = (SET_CUR & 0x80) ? usb_rcvctrlpipe(myuvc_udev, 0)
: usb_sndctrlpipe(myuvc_udev, 0);
type |= (SET_CUR & 0x80) ? USB_DIR_IN : USB_DIR_OUT;
//进行发送,ret是接收的字节数
//usb_control_msg是没有用到urb的在USB中简单进行发送和接收的一种机制，用于少量的数据通信
ret = usb_control_msg(myuvc_udev, pipe, SET_CUR, type, VS_PROBE_CONTROL << 8,
0 << 8 | myuvc_streaming_intf, data, size, 5000);
kfree(data);//释放缓冲区
return (ret < 0) ? ret : 0;
}
3、取出参数
static int myuvc_get_streaming_params(struct myuvc_streaming_control *ctrl)
{
u8 *data;
u16 size;
int ret;
u8 type;
unsigned int pipe;
size = uvc_version >= 0x0110 ? 34 : 26;
data = kmalloc(size, GFP_KERNEL);
type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
if (data == NULL)
return -ENOMEM;
pipe = (GET_CUR & 0x80) ? usb_rcvctrlpipe(myuvc_udev, 0)
: usb_sndctrlpipe(myuvc_udev, 0);
type |= (GET_CUR & 0x80) ? USB_DIR_IN : USB_DIR_OUT;
ret = usb_control_msg(myuvc_udev, pipe, GET_CUR, type, VS_PROBE_CONTROL << 8,
0 << 8 | myuvc_streaming_intf, data, size, 5000);
if(ret < 0)
goto done;
ctrl->bmHint = le16_to_cpup((__le16 *)&data[0]);
ctrl->bFormatIndex = data[2];
ctrl->bFrameIndex = data[3];
ctrl->dwFrameInterval = le32_to_cpup((__le32 *)&data[4]);
ctrl->wKeyFrameRate = le16_to_cpup((__le16 *)&data[8]);
ctrl->wPFrameRate = le16_to_cpup((__le16 *)&data[10]);
ctrl->wCompQuality = le16_to_cpup((__le16 *)&data[12]);
ctrl->wCompWindowSize = le16_to_cpup((__le16 *)&data[14]);
ctrl->wDelay = le16_to_cpup((__le16 *)&data[16]);
ctrl->dwMaxVideoFrameSize = get_unaligned_le32(&data[18]);
ctrl->dwMaxPayloadTransferSize = get_unaligned_le32(&data[22]);
if (size == 34) {
ctrl->dwClockFrequency = get_unaligned_le32(&data[26]);
ctrl->bmFramingInfo = data[30];
ctrl->bPreferedVersion = data[31];
ctrl->bMinVersion = data[32];
ctrl->bMaxVersion = data[33];
} else {
// ctrl->dwClockFrequency = stream->dev->clock_frequency;
ctrl->bmFramingInfo = 0;
ctrl->bPreferedVersion = 0;
ctrl->bMinVersion = 0;
ctrl->bMaxVersion = 0;
}
done:
kfree(data);
return (ret < 0) ? ret : 0;
}
4、设置参数
static int myuvc_set_streaming_params(struct myuvc_streaming_control *ctrl)
{
__u8 *data;
__u16 size;
int ret;
__u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
unsigned int pipe;
size = uvc_version >= 0x0110 ? 34 : 26;
data = kzalloc(size, GFP_KERNEL);
if (data == NULL)
return -ENOMEM;
*(__le16 *)&data[0] = cpu_to_le16(ctrl->bmHint);
data[2] = ctrl->bFormatIndex;
data[3] = ctrl->bFrameIndex;
*(__le32 *)&data[4] = cpu_to_le32(ctrl->dwFrameInterval);
*(__le16 *)&data[8] = cpu_to_le16(ctrl->wKeyFrameRate);
*(__le16 *)&data[10] = cpu_to_le16(ctrl->wPFrameRate);
*(__le16 *)&data[12] = cpu_to_le16(ctrl->wCompQuality);
*(__le16 *)&data[14] = cpu_to_le16(ctrl->wCompWindowSize);
*(__le16 *)&data[16] = cpu_to_le16(ctrl->wDelay);
put_unaligned_le32(ctrl->dwMaxVideoFrameSize, &data[18]);
put_unaligned_le32(ctrl->dwMaxPayloadTransferSize, &data[22]);
if (size == 34) {
put_unaligned_le32(ctrl->dwClockFrequency, &data[26]);
data[30] = ctrl->bmFramingInfo;
data[31] = ctrl->bPreferedVersion;
data[32] = ctrl->bMinVersion;
data[33] = ctrl->bMaxVersion;
}
pipe = (SET_CUR & 0x80) ? usb_rcvctrlpipe(myuvc_udev, 0)
: usb_sndctrlpipe(myuvc_udev, 0);
type |= (SET_CUR & 0x80) ? USB_DIR_IN : USB_DIR_OUT;
//跟try不一样的是，刚才是 VS_PROBE_CONTROL（枚举尝试），现在是VS_COMMIT_CONTROL（设置参数）
ret = usb_control_msg(myuvc_udev, pipe, SET_CUR, type, VS_COMMIT_CONTROL << 8,
0 << 8 | myuvc_streaming_intf, data, size, 5000);
0 << 8 | myuvc_streaming_intf这里索引字段是2个字节，描述的是接口号，因为有两种接口，一种是视频流接口（这些参数存储的地方），一种是视频控制接口
kfree(data);
return (ret < 0) ? ret : 0;
}
5、probe函数
static int myuvc_probe(struct usb_interface *intf,
const struct usb_device_id *id)
{
static int cnt = 0;
//interface_to_usbdev() -- 根据usb_interface指针intf获取usb_device的地址
struct usb_device *dev = interface_to_usbdev(intf);//根据接口找到对应的设备
int ret;
myuvc_udev = dev;
printk("myuvc_probe : cnt = %d\n", cnt++);
if (cnt == 1)
{
//控制接口的编号
myuvc_control_intf = intf->cur_altsetting->desc.bInterfaceNumber;
}
else if (cnt == 2)
{
//流接口的编号
myuvc_streaming_intf = intf->cur_altsetting->desc.bInterfaceNumber;
}
if (cnt == 2)
{
/* 1. 分配一个video_device结构体 */
myuvc_vdev = video_device_alloc();
/* 2. 设置 */
/* 2.1 */
myuvc_vdev->release = myuvc_release;
/* 2.2 */
myuvc_vdev->fops = &myuvc_fops;
/* 2.3 */
myuvc_vdev->ioctl_ops = &myuvc_ioctl_ops;
/* 3. 注册 */
video_register_device(myuvc_vdev, VFL_TYPE_GRABBER, -1);
其中：第一个参数struct video_device *vdev是想注册的video device的结构体；
第二个参数是视频设备类型，在此头文件(v4l2-dev.h中)，定义了几种视频设备类型：
#defineVFL_TYPE_GRABBER 0 //图像采集设备
#defineVFL_TYPE_VBI 1 //从视频消隐的时间段获得信息的设备
#defineVFL_TYPE_RADIO 2 //无线电设备
#defineVFL_TYPE_SUBDEV 3 //视频设备（不确定）
#defineVFL_TYPE_MAX 4 //最大值
第三个参数是注册的设备节点号；
device node number
(0 == /dev/video0, 1 == /dev/video1, ... -1 == first free)
此函数注册一个V4L2 Device。 指定类型，指定device node.（通过参数3）
/* 为了确定带宽,使用哪一个setting */
/* a. 测试参数 */
ret = myuvc_try_streaming_params(&myuvc_params);
printk("myuvc_try_streaming_params ret = %d\n", ret);
/* b. 取出参数 */
ret = myuvc_get_streaming_params(&myuvc_params);
printk("myuvc_get_streaming_params ret = %d\n", ret);
/* c. 设置参数 */
ret = myuvc_set_streaming_params(&myuvc_params);
printk("myuvc_set_streaming_params ret = %d\n", ret);
myuvc_print_streaming_params(&myuvc_params);
}
return 0;
}