Re: Wrong RS485 RTS polarity in 8250 OMAP UART Driver vs DT binding?

[Lukas Wunner]

On Wed, Mar 15, 2023 at 09:41:56PM +0100, Francesco Dolcini wrote:
> We have working hardware, using another UART that expect
> rs485-rts-active-low, and the exact same HW, when using OMAP uart,
> requires rs485-rts-active-high (the HW is modular, so we are really just
> changing the uart, keeping the same RS485 transceiver / connections).
> 
> What's going on there? Is the semantic of the 8250_omap driver just the
> opposite as it should be?

Yes, sadly, for historic reasons.

See these threads:

https://lore.kernel.org/linux-serial/20220329085050.311408-1-matthias.schiffer@xxxxxxxxxxxxxxx/

https://lore.kernel.org/linux-serial/2de36eba3fbe11278d5002e4e501afe0ceaca039.1663863805.git.lukas@xxxxxxxxx/


> Am I doing something wrong in the device tree?

No, but regrettably you need a separate device tree depending on which SoC
you're using.

Thanks,

Lukas