scsi command timeout_per_command and scsi device timeout

Hi,

What is the relation between scsi_cmd->timeout_per_command and scsi_device->timeout?
I set a timeout value for scsi_device->timeout in slave_configure, but I don't see this value being taken by scsi_cmd->timeout_per_command.

If they are not related, then how can I set command timeout for all commands to my driver to avoid command timeouts.

with regards,
Anil