Android之Camera預覽過程中插拔攝像頭節點後移
阿新 • • 發佈:2019-02-13
現象:
在使用Camera Preview時;熱插拔攝像頭會導致裝置節點由/dev/video0變為/dev/video1,或者插入多個video裝置時,會變為/dev/video1、/dev/video2......。
一、首先看裝置節點的建立
drivers/media/video/uvc/uvc_driver.c
static int uvc_probe(struct usb_interface *intf, const struct usb_device_id *id){ if (v4l2_device_register(&intf->dev, &dev->vdev) < 0) goto error; }
drivers/media/video/v4l2-devices.c
int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
{
err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1, sd->owner);
}
drivers/media/video/v4l2-dev.c
int __video_register_device(struct video_device *vdev, int type, int nr, int warn_if_nr_in_use, struct module *owner){ int nr = -1; int minor_cnt = 64; nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt); //裝置節點名,即“/dev/video*” vdev->num = nr; devnode_set(vdev); //該vdev->numd對應的符號被置為1 /* devnode_set(vdev); //該vdev->numd對應的符號被置為1 devnode_clear(vdev); //該vdev->numd對應的符號被置為0 */ name_base = "video"; dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num); ret = device_register(&vdev->dev); vdev->dev.release = v4l2_device_release; //該介面會呼叫devnode_clear(vdev) }
二、問題解決
最終修改,問題解決:
drivers/media/video/uvc/uvc_driver.c
static void uvc_disconnect(struct usb_interface *intf){ uvc_unregister_video(dev); } static void uvc_unregister_video(struct uvc_device *dev){ video_unregister_device(stream->vdev); //修改該介面函式 if (atomic_dec_and_test(&dev->nstreams)){ //這裡也有些問題,但不是根本原因 uvc_delete(dev); } }
我的修改:
drivers/media/video/v4l2-dev.c
void video_unregister_device(struct video_device *vdev){
devnode_clear(vdev);//add by tankai
device_unregister(&vdev->dev); //該介面本身會呼叫v4l2_device_release,但卻沒有
}
三、其他解決辦法1.這是一個網友在HAL層的解決辦法
2.我們在HAL的解決辦法
hardware/amlogic/camera/AppCallbackNotifier.cpp
//All sub-components of Camera HAL call this whenever any error happens
void AppCallbackNotifier::errorNotify(int error)
{
LOG_FUNCTION_NAME;
CAMHAL_LOGEB("AppCallbackNotifier received error %d", error);
// If it is a fatal error abort here!
if((error == CAMERA_ERROR_FATAL) || (error == CAMERA_ERROR_HARD)) {
//We kill media server if we encounter these errors as there is
//no point continuing and apps also don't handle errors other
//than media server death always.
abort();
return;
}
if ( ( NULL != mCameraHal ) &&
( NULL != mNotifyCb ) &&
( mCameraHal->msgTypeEnabled(CAMERA_MSG_ERROR) ) )
{
CAMHAL_LOGEB("AppCallbackNotifier mNotifyCb %d", error);
mNotifyCb(CAMERA_MSG_ERROR, CAMERA_ERROR_UNKNOWN, 0, mCallbackCookie);
mCameraHal->release(); //add by tankai
}
LOG_FUNCTION_NAME_EXIT;
}