On Mon, Jun 22, 2015 at 10:11:35PM +0200, Stefan Agner wrote: > On 2015-06-22 19:26, Johan Hovold wrote: > > Instead, hang the gpio chip directly off the usb interface (not the > > port), add a new config option, and keep the gpio implementation under > > drivers/usb/serial (possibly in its own file ftdi_sio-gpio.c). > > Agreed sounds like a good plan. Will try this approach in v2. > > Except I don't think hanging it directly to the USB interface is the > right thing to do. > > Looking at the block diagram of FT232R or FT232H, the CBUS pins seem to > be part of the UART/FIFO controller. And I think the dual UART FT2232D > actually supports controlling the CBUS pins of the two UART controllers > individually, at least the block diagram thereof suggests so. The port is a Linux abstraction, and for FTDI we happen to have exactly one port child device per USB interface. As I see it, the gpio controller for the CBUS pins should be a sibling rather than a child device to the port. Note that we'd still have two gpio-controllers on FT2232D (one per USB interface). I'm aware that this requires some restructuring of the ftdi_sio-driver (e.g. the device type and ftdi-interface number should be a feature of the usb-serial rather than usb-serial-port device). Thanks, Johan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
