Hi all, Summary Question:
Broadly, I am trying to understand where a interrupt callback is specified if not already specified by usbd_open_pipe_intr(9). Specifically, for the athn(4) driver, I am trying to understand if/how athn_usb_intr() is executed for Tx interrupts. This seems necessary yet I do not see a callback specified by usbd_setup_xfer(9) or by usbd_open_pipe_intr(9). All code is located in sys/dev/usb/if_athn_usb.c. Question Walk-through: >From reading the code, it seems that the athn_usb_intr() function is called whenever a Tx interrupt is triggered. The reason I think this is because there is a tsleep_nsec(9) for a Tx interrupt that awaits for a wakeup(9) that only happens in athn_usb_intr(). The 3 relevant steps are listed below in athn_usb_htc_setup() under the comment "Set credits for WLAN Tx pipe": 1. athn_usb_htc_msg(), which runs usbd_setup_xfer(9) and usbd_transfer(9) for a Tx interrupt. The callback is set to NULL. 2. usc->wait_msg_id is set to AR_HTC_MSG_CONF_PIPE_RSP. 3. A tsleep_nsec() on &usc->wait_msg_id The only place I see a wakeup(9) on &usc->wait_msg_id is within athn_usb_intr(), on condition that usc->wait_msg_id is set to AR_HTC_MSG_CONF_PIPE_RSP. Seems like a perfect match. Additionally, I do not see an Rx interrupt anywhere else. But even if it does happen somewhere and I am just missing it, the only place AR_HTC_MSG_CONF_PIPE_RSP is used is step 2. Rx interrupt callbacks to athn_usb_intr() are specified by the usbd_open_pipe_intr(9) call in athn_usb_open_pipes(). That seems explicit. But for the Tx interrupt, I do not see where the mapping to athn_usb_intr() is. Please assist, thank you. - Farhan
