netdev - Re: [PATCH net-next 1/2] mlxsw: Register physical ports as a devlink resource

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Message-ID: <20210113133902.GH3565223@nanopsycho.orion>
Date:   Wed, 13 Jan 2021 14:39:02 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Ido Schimmel <idosch@...sch.org>
Cc:     Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        davem@...emloft.net, jiri@...dia.com, danieller@...dia.com,
        mlxsw@...dia.com, Ido Schimmel <idosch@...dia.com>
Subject: Re: [PATCH net-next 1/2] mlxsw: Register physical ports as a devlink
 resource

Wed, Jan 13, 2021 at 09:32:41AM CET, idosch@...sch.org wrote:
>On Tue, Jan 12, 2021 at 08:21:22PM -0800, Jakub Kicinski wrote:
>> On Tue, 12 Jan 2021 10:39:30 +0200 Ido Schimmel wrote:
>> > From: Danielle Ratson <danieller@...dia.com>
>> > 
>> > The switch ASIC has a limited capacity of physical ('flavour physical'
>> > in devlink terminology) ports that it can support. While each system is
>> > brought up with a different number of ports, this number can be
>> > increased via splitting up to the ASIC's limit.
>> > 
>> > Expose physical ports as a devlink resource so that user space will have
>> > visibility to the maximum number of ports that can be supported and the
>> > current occupancy.
>> 
>> Any thoughts on making this a "generic" resource?
>
>It might be possible to allow drivers to pass the maximum number of
>physical ports to devlink during their initialization. Devlink can then
>use it as an indication to register the resource itself instead of the
>driver. It can report the current occupancy without driver intervention
>since the list of ports is maintained in devlink.
>
>There might be an issue with the resource identifier which is a 64-bit
>number passed from drivers. I think we can partition this to identifiers
>allocated by devlink / drivers.
>
>Danielle / Jiri?

There is no concept of "generic resource". And I think it is a good
reason for it, as the resource is something which is always quite
hw-specific. Port number migth be one exception. Can you think of
anything else? If not, I would vote for not having "generic resource"
just for this one case.