usb_bulk_msg (9) - Linux Manuals

usb_bulk_msg: Builds a bulk urb, sends it off and waits for completion

NAME

usb_bulk_msg - Builds a bulk urb, sends it off and waits for completion

SYNOPSIS

int usb_bulk_msg(struct usb_device * usb_dev, unsigned int pipe, void * data, int len, int * actual_length, int timeout);

ARGUMENTS

usb_dev

pointer to the usb device to send the message to

pipe

endpoint "pipe" to send the message to

data

pointer to the data to send

len

length in bytes of the data to send

actual_length

pointer to a location to put the actual length transferred in bytes

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 bulk 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.

Because there is no usb_interrupt_msg and no USBDEVFS_INTERRUPT ioctl, users are forced to abuse this routine by using it to submit URBs for interrupt endpoints. We will take the liberty of creating an interrupt URB (with the default interval) if the target is an interrupt endpoint.

RETURN

If successful, 0. Otherwise a negative error number. The number of actual bytes transferred will be stored in the actual_length parameter.

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