Hi Marek,
On Sun, 25 Aug 2019 18:36:09 +0200, Marek Behun <marek.be...@nic.cz> wrote:
> > Aren't you relying on -ENODEV as well?
>
> Vivien, I am not relying o -ENODEV. I changed the serdes_get_lane
> semantics:
> - previously:
> - if port has a lane for current cmode, return given lane number
> - otherwise return -ENODEV
> - if other error occured during serdes_get_lane, return that error
> (this never happened, because all implementations only need port
> number and cmode, and cmode is cached, so no function was called
> that could err)
> - after this commit:
> - if port has a lane for current cmode, return 0 and put lane number
> into *lane
> - otherwise return 0 and put -1 into *lane
> - if error occured, return that error number
>
> I removed the -ENODEV semantics for "no lane on port" event.
> There are two reasons for this:
> 1. once you requested lane number to be put into a place pointed to
> by a pointer, rather than the return value, the code seemed better
> to me (you may of course disagree, this is a personal opinion) when
> I did:
> if (err)
> return err;
> if (lane < 0)
> return 0;
> rather than
> if (err == -ENODEV)
> return 0;
> if (err)
> return err;
A single return path for invalid queries, eventually checking a specific
error, is always more idiomatic and better than checking two places which
could lead in mistakes as your previous patch did. So this is more readable:
if (err)
return err;
or:
if (err && err != -ENODEV)
return err;
or:
if (err) {
if (err = -ENODEV)
err = 0;
return err;
}
> 2. some future implementation may actually need to call some MDIO
> read/write functions, which may or may not return -ENODEV. That
> could conflict with the -ENODEV returned when there is no lane.
The current code is already using -ENODEV to inform about "no lane for port",
even if it can be used by lower level functions, same as -EINVAL. That is fine.
So if you have to respin the series again, I would really prefer to see an
unsigned lane parameter, otherwise, fine...
Thanks,
Vivien
