Re: [PATCH v3 6/6] tty: serial: 8250: Add support for MOXA PCIe boards to switch interface between RS422/RS485

[Crescent CY Hsieh]

On Mon, Oct 23, 2023 at 12:25:18PM +0300, Ilpo Järvinen wrote:
> On Wed, 18 Oct 2023, Crescent CY Hsieh wrote:
> > +		/*
> > +		 * RS232 is not supported for MOXA PCIe boards with device IDs
> > +		 * matching the pattern 0x*3**.
> > +		 */
> > +		if (pci_moxa_match_second_digit(device, 0x0300))
> > +			return -EOPNOTSUPP;
> 
> This is not the correct error code I think. Maybe return -ENXIO instead.

I think EOPNOTSUPP or ENOTSUPP would be more reasonable, they directly
indicates "operation is not supported".

However, EOPNOTSUPP is used for network-related and ENOTSUPP is used for
NFSv3 protocol, even though they are already been used throughout the
kernel.

Maybe add a new one stand for serial, or clean them up into a general
one, or use EOPNOTSUPP and ENOTSUPP just for now?

---
Sincerely,
Crescent CY Hsieh