Trait devices::usb::xhci::ring_buffer_controller::TransferDescriptorHandler

source · 
pub trait TransferDescriptorHandler {
    // Required method
    fn handle_transfer_descriptor(
        &self,
        descriptor: Vec<AddressedTrb>,
        complete_event: Event
    ) -> Result<()>;

    // Provided method
    fn stop(&self) -> bool { ... }
}
Expand description

TransferDescriptorHandler handles transfer descriptor. User should implement this trait and build a ring buffer controller with the struct.

Required Methods§

source

fn handle_transfer_descriptor( &self, descriptor: Vec<AddressedTrb>, complete_event: Event ) -> Result<()>

Process descriptor asynchronously, write complete_event when done.

Provided Methods§

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fn stop(&self) -> bool

Stop is called when trying to stop ring buffer controller. Returns true when stop must be performed asynchronously. This happens because the handler is handling some descriptor asynchronously, the stop callback of ring buffer controller must be called after the async part is handled or canceled. If the TransferDescriptorHandler decide it could stop immediately, it could return false. For example, if a handler submitted a transfer but the transfer has not yet finished. Then guest kernel requests to stop the ring buffer controller. Transfer descriptor handler will return true, thus RingBufferController would transfer to Stopping state. It will be stopped when all pending transfer completed. On the other hand, if hander does not have any pending transfers, it would return false.

Implementors§