Re: [PATCH 1/1] MicroSemi Switchtec management interface driver

[Emil Velikov]

On 2 February 2017 at 16:37, Logan Gunthorpe <logang@xxxxxxxxxxxx> wrote:
>
>
> On 01/02/17 05:10 AM, Emil Velikov wrote:
>> You can keep it roughly as-is if you're ~reasonably certain one won't
>> change it in the future.
>
> I've made the change anyway. I think it's better now.
>
>> Some teams frown upon adding new IOCTL(s) where existing ones can be
>> made backward/forward compatible.
>> I'm not fully aware of the general direction/consensus on the topic,
>> so it might be a minority.
>
> Sure, I just don't know what might be needed in the future so it's hard
> to add a version or flags ioctl now.
>
Yes knowing how things will need to change in the is hard. That's why
the documentation suggestions adding a flag to the ioctl structs.
It [the flag] might imply certain functional/implementation change,
support for new/deprecation of old features and others.

>> On the other hand, reading through sysfs for module version in order
>> to use IOCTL A or B sounds quite hacky. Do you have an example where
>> this is used or pointed out as good approach ?
>
> I don't know of anything doing it that way now. But it sure would be
> easy and make a bit of sense. (We'd actually use the module version for
> something useful.) Either way, it would really depend on if and how
> things change in the future. The point is there are options to expand if
> needed.
>
The part that nobody else is doing such a thing should ring a bell ;-)

It's no my call, but if it was I'd stick with the existing approach
and not "reinvent the wheel" sort of speak.

Thanks
Emil