In the smsc911x Ethernet chip driver, I'm changing the FIFO write and read to DMA write and read. By the way, this driver uses loopback test during initialization using a simple test packet. I registered the DMA controller irq using request_irq(irq, handler, flags, name, dev) which calls request_threaded_irq(irq, handler, NULL, flags, name, dev). The process goes into sleep using wait_event_interruptible() after DMA command and I've seen the ISR handler is called by the DMA completion, and during the ISR, wake_up_interruptible() is called to wake up the process. But when the program runs I get this error message below during the first interrupt processing. "IRQ 2 device ald_dmac returned IRQ_WAKE_THREAD but no thread function available" I don't know why ald_dmac returned IRQ_WAKE_THREAD (because my interrupt handler only returns IRQ_HANDLED), and I have a feeling that in this case (processing going to sleep and woken up by the ISR), I should use some other method to register my interrupt. Can anybody give me some advice? Thanks a lot in advance. Chan Kim