---
title: ClearStall
framework: usbdriverkit
role: symbol
role_heading: Instance Method
path: usbdriverkit/iousbhostpipe/clearstall
---

# ClearStall

Clears the halt condition of the pipe.

## Declaration

```occ
virtual kern_return_t ClearStall(bool withRequest);
```

## Parameters

- `withRequest`: A Boolean indicating whether to send a CLEAR_FEATURE request to the device with the value ENDPOINT_HALT. To keep the device’s data toggle synchronized with the host’s data toggle, it’s recommended that you specify doc://com.apple.documentation/documentation/Swift/true, but you may safely specify doc://com.apple.documentation/documentation/Swift/false for control endpoints. For information about this request, see section 9.4.1 of the USB 2.0 specification.

## Return Value

Return Value kIOReturnSuccess on success, or another value if an error occurs. See Error Codes.

## Discussion

Discussion When a bulk or interrupt USB endpoint encounters an I/O error other than a timeout, it transitions to a halted state that you must clear if you want to perform additional I/O on the endpoint. Call this method to clear the halted condition for the endpoint. This method aborts all pending I/O on the endpoint and resets its data toggle. If an intermediate hub is between the device and your driver, this method also sends a CLEAR_TT_BUFFER control request (USB 2.0, section 11.24.2.3) to the hub.

## See Also

### Adjusting the Pipe’s Status

- [AdjustPipe](usbdriverkit/iousbhostpipe/adjustpipe.md)