usb_control_msg (9) - Linux Manuals

usb_control_msg: Builds a control urb, sends it off and waits for completion

Command to display usb_control_msg manual in Linux: $ man 9 usb_control_msg

NAME

usb_control_msg - Builds a control urb, sends it off and waits for completion

SYNOPSIS

int usb_control_msg(struct usb_device * dev, unsigned int pipe, __u8 request, __u8 requesttype, __u16 value, __u16 index, void * data, __u16 size, int timeout);

ARGUMENTS

dev

: pointer to the usb device to send the message to

pipe

: endpoint "pipe" to send the message to

request

: USB message request value

requesttype

: USB message request type value

value

: USB message value

index

: USB message index value

data

: pointer to the data to send

size

: length in bytes of the data to send

timeout

: time in msecs to wait for the message to complete before timing out (if 0 the wait is forever)

CONTEXT

!in_interrupt ()

DESCRIPTION

This function sends a simple control message to a specified endpoint and waits for the message to complete, or timeout.

Don't use this function from within an interrupt context, like a bottom half handler. If you need an asynchronous message, or need to send a message from within interrupt context, use usb_submit_urb. If a thread in your driver uses this call, make sure your disconnect method can wait for it to complete. Since you don't have a handle on the URB used, you can't cancel the request.

RETURN

If successful, the number of bytes transferred. Otherwise, a negative error number.