On 18/03/14 16:55, Felipe Balbi wrote: > Hi Mark, > > I'm looking at the omap-serial driver and saw that you added rts-gpio > binding in commit 4a0ac0f55b18dc297a87a85417fcf068658bf103 (OMAP: add > RS485 support) but, as it turns out, gpio0_13 and gpio2_15 are both > actual RTS signals. > > Instead of adding that extra GPIO handling, why didn't you just mux > those signals as RTS and enable auto-RTS/auto-CTS feature ? > > It looks to me like that's highly unnecessary binding. I agree !! I think it was to allow delays pre- and post- sending the comms data. Several RS485 drivers require a "warm up" time before they will transmit data correctly, and also need a "cool down" time to prevent clipping of the last few bits of data. IIRC the built-in RTS handling did not allow for this. It also allows the RTS signal to be "inverted", again required for some RS485 driver chips. However, I'll dig into why I did this and report back. Mark J. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
