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

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Oct 24, 2023 at 03:48:07PM +0800, Crescent CY Hsieh wrote:
> 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?

-ENODEV should be the proper one here.

thanks,

greg k-h