[Bug 222665] [uftdi] Cannot send anything if characters received ahead of first use of ftdi chip

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=222665

Ian Lepore <ian at FreeBSD.org> changed:

           What    |Removed                     |Added
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             Status|New                         |Open
           Assignee|freebsd-usb at FreeBSD.org     |ian at FreeBSD.org

--- Comment #3 from Ian Lepore <ian at FreeBSD.org> ---
I'll look into this.

I can confirm that a large change in the ftdi driver between 8.2 and 10.x was
that the old code would reset the chip on open(), and now that doesn't happen. 
The reset was harmful for some embedded uses, such as when the chip is used in
mpsse or bitbang mode.

How is your rs485 transceiver connected to the ftdi?  Is the transmitter
connected to #TXDEN, and if so, are you using the eeprom to reconfigure that
pin from RI to TXDEN?  Is the receive side squelched in hardware (as suggested
in the ftdi datasheet, or otherwise) when the transmit side is active?

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