On Wednesday, August 17, 2016 8:14:42 PM CEST Rob Herring wrote: > > Before I spend more time on this, I'm looking mainly for feedback on the > general direction and structure (the interface with the existing serial > drivers in particular). Aside from the things that have already been mentioned in the discussion, I wonder how this should relate to the drivers/input/serio framework. My impression is that there is some overlap in what you want to do here, and what serio does today as a line discipline on top of a tty line discipline (and on top of other non-uart serial connections), so we should look into whether the two can be unified or not. Here is what I found so far: For all I can tell, serio is only used for drivers/input/ but could easily be extended to other subsystems. It currently uses its own binary ID matching between drivers and devices through user space interfaces, though adding a DT binding for it would appear to be a good idea regardless. It also has a bus_type already, and with some operations defined on it. In particular, it has an "interrupt" method that is used to notify the client driver when a byte is available (and pass that byte along with it). This seems to be a useful addition to what you have. Since it is based on sending single characters both ways, transferring large amounts of data would be slower, but the interface is somewhat simpler. In principle, both character based and buffer based interfaces could coexist here as they do in some other interfaces (e.g. smbus). While serio is typically layered on top of tty-ldisc (on top of tty_port, which is often on top of uart_port) or on top of i8042/ps2 drivers, I suppose we could add another back-end on top of uart_port directly to avoid the ldisc configuration in many cases when using devicetree based setup. This should also address the main concern that Alan raised about generality of the subsystem: we'd always leave the option of either manual configuration of the tty-ldisc (for any tty_port) or configuring on-chip devices (using uart_port) directly through DT. Of course the same thing can be done if we hook into tty_port rather than uart_port. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
