On Tue, Mar 18, 2014 at 05:04:47PM +0000, Mark Jackson wrote: > 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. you might be right here. I can't find anywhere to write rts delays. Weird... digging TRM. > 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. cool, thanks -- balbi
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