Adjusting scsi_cmnd timeout_per_command value?

Is it possible to control the timeout value of scsi commands that are submitted to a particular device from an upper layer driver? I figured I'd have to either change the scsi_device's timeout value or the request's timeout value. Given that I'm relying on the block layer's __make_request function to build a request, is there a safe way to adjust the timeout value for a scsi_device from the upper layer? Or is there a better way to do this, i.e. something similar to how sg_timeout is associated with a request_queue and can subsequently be used to set timeout values for sg_io's? Or maybe a scsi device timeout value should be under the control of the LLDs only?

Thanks!!
lan