---
title: StopIO
framework: VideoDriverKit
role: symbol
role_heading: Instance Method
platforms: [driverkit 27.0+]
path: videodriverkit/iouservideoclockdevice/stopio
---

# StopIO

Tells the clock device to stop IO.

## Declaration

```occ
virtual kern_return_t StopIO(IOUserVideoStartStopFlags in_flags);
```

## Parameters

- `in_flags`: IOUserVideoStartStopFlags to indicate how IO is stopping.

## Discussion

Discussion The default implementation always returns kIOReturnSuccess. Subclass and override this method to handle any hardware specific things when IO is stopping, then call the superclass implementation to update IO state.

## See Also

### Performing I/O

- [StartIO](videodriverkit/iouservideoclockdevice/startio.md)
- [IOUserVideoStartStopFlags](videodriverkit/videodriverkit/iouservideostartstopflags.md)