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    SubjectRe: [PATCH] USB: ftdi_sio: Remove tty->low_latency.
    Having had a look through the driver someone with docs or similar needs
    to explain how the ftdi_sio does hardware and software flow control. It
    has throttle/unthrottle methods but these just stall the URB queuing and
    don't do any flow processing of their own at all. Does the ftdi_sio do
    this in hardware when the urbs run low ?

    Otherwise it can certainly be simplified a lot. In particular at the
    point you get throttle event you've got about 64K of cushion to react
    (flow control being async anyway) and you actually *want* to pull data
    after you whack the modem lines because the other end also has a latency
    to respond.

    So all the clever partial processing of urb stuff is overkill. Whether it
    needs not to repost urbs to the device or to implement flow control in
    software I don't know without docs.

    With that done the driver ought to be a good deal easier to debug.


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