Hello Johan, This patch series adds support for a family of FTDI-based devices that need special quirks in the ftdi_sio driver. The devices in question are produced by my hobby company Falconia Partners LLC, and I got a block of PIDs from FTDI (from their VID), so I assign custom USB IDs when I program FT2232 EEPROMs on my boards. These custom USD IDs are intended to facilitate conditionalized quirks in the ftdi_sio driver, as implemented in this patch series. The 3 devices (3 USB IDs) for which this patch series adds support consist of two JTAG+UART adapters and one dual UART adapter. Support for the two JTAG+UART adapters consists of nothing more than adding them to the USB ID table with the already existing ftdi_jtag_quirk applied, but the dual UART adapter (DUART28C) is more involved. The special quirk with DUART28C is that FT2232D BDBUS2 and BDBUS4 outputs (which would normally be Channel B RTS and DTR, respectively) have been repurposed to drive power and reset controls to Calypso targets, and these power and reset controls must not be triggered on their own - instead their control needs to be left to special userspace applications. The problem is that the standard behaviour of all tty devices under Linux (not just ftdi_sio and not just USB serial, but apparently all ttys) is that DTR and RTS are always unconditionally asserted as soon as the tty device (ttyUSB in the present case) is opened, and userspace does not get a chance to intervene. It is not my place to debate whether this behaviour is good or not for true serial ports where DTR/RTS really are DTR/RTS, but it is a total killer for non-standard hardware where the USB to serial chip's DTR & RTS outputs have been repurposed to do something disruptive like power and reset control. The solution that works beautifully in my own hardware lab is contained in the present patch series: the new DUART28C-specific quirk simply suppresses automatic assertion of DTR&RTS for Channel B on this device. Userspace can then trigger PWON and RESET actions as needed with TIOCMBIS ioctls (followed by a delay and TIOCMBIC to make a pulse), and everything works beautifully. If I could get this DUART28C quirk (conditionalized on the USB ID which FTDI officially allocated to me) mainlined, it would spare my users the pain of having to apply this patch themselves locally. TIA, Mychaela Mychaela N. Falconia (3): USB: serial: ftdi_sio: add support for FreeCalypso JTAG+UART adapters USB: serial: ftdi_sio: pass port to quirk port_probe functions USB: serial: ftdi_sio: add support for FreeCalypso DUART28C adapter drivers/usb/serial/ftdi_sio.c | 72 +++++++++++++++++++++++++++++++++------ drivers/usb/serial/ftdi_sio_ids.h | 8 +++++ 2 files changed, 70 insertions(+), 10 deletions(-) -- 2.9.0 base-commit: 2bb70f0a4b238323e4e2f392fc3ddeb5b7208c9e
