I recently posted some questions on the linux kernel mailing list about usb driver interaction through the tty layer. My reference for now is the usb-skeleton in 2.4.27.
My first question was why they n_tty.c:write_chan() function does *NOT* call schedule() for tty_driver:write() calls that write all of the data requested. From a userland perspective, this means that a write() cannot be guaranteed to happen successfully because we may still be waiting on an interrupt to complete the usb_submit_urb(). My second question is, if the implementation of n_tty.s:write_chan() is correct, why don't usb drivers that implement the tty_driver interface block write() calls until the completion of the usb_submit_urb()?? It seems to me that userland protocols that rely on serialized I/O will have a real problem with this implementation. Can anyone comment on this? -- Ryan ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://productguide.itmanagersjournal.com/ _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
