netdev - Re: [PATCH net-next 1/3] devlink: Introduce PCI PF port flavour and port attribute

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Date:   Wed, 3 Jul 2019 16:33:54 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Parav Pandit <parav@...lanox.com>
Cc:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Jiri Pirko <jiri@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Saeed Mahameed <saeedm@...lanox.com>,
        "vivien.didelot@...il.com" <vivien.didelot@...il.com>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>
Subject: Re: [PATCH net-next 1/3] devlink: Introduce PCI PF port flavour and
 port attribute

Wed, Jul 03, 2019 at 03:49:51PM CEST, parav@...lanox.com wrote:
>
>
>> -----Original Message-----
>> From: Jiri Pirko <jiri@...nulli.us>
>> Sent: Wednesday, July 3, 2019 4:07 PM
>> To: Parav Pandit <parav@...lanox.com>
>> Cc: Jakub Kicinski <jakub.kicinski@...ronome.com>; Jiri Pirko
>> <jiri@...lanox.com>; netdev@...r.kernel.org; Saeed Mahameed
>> <saeedm@...lanox.com>; vivien.didelot@...il.com; andrew@...n.ch;
>> f.fainelli@...il.com
>> Subject: Re: [PATCH net-next 1/3] devlink: Introduce PCI PF port flavour and
>> port attribute
>> 
>> Wed, Jul 03, 2019 at 06:46:13AM CEST, parav@...lanox.com wrote:
>> >
>> >
>> >> -----Original Message-----
>> >> From: Jakub Kicinski <jakub.kicinski@...ronome.com>
>> >> Sent: Wednesday, July 3, 2019 7:46 AM
>> >> To: Parav Pandit <parav@...lanox.com>
>> >> Cc: Jiri Pirko <jiri@...lanox.com>; netdev@...r.kernel.org; Saeed
>> >> Mahameed <saeedm@...lanox.com>
>> >> Subject: Re: [PATCH net-next 1/3] devlink: Introduce PCI PF port
>> >> flavour and port attribute
>> >>
>> >> On Wed, 3 Jul 2019 02:08:39 +0000, Parav Pandit wrote:
>> >> > > If you want to expose some device specific eswitch port ID please
>> >> > > add a new attribute for that.
>> >> > > The fact that that ID may match port_number for your device today
>> >> > > is coincidental.  port_number, and split attributes should not be
>> >> > > exposed for PCI ports.
>> >> >
>> >> > So your concern is non mellanox hw has eswitch but there may not be
>> >> > a unique handle to identify a eswitch port?
>> >>
>> >> That's not a concern, no.  Like any debug attribute it should be optional.
>> >>
>> >> > Or that handle may be wider than 32-bit?
>> >>
>> >> 64 bit would probably be better, yes, although that wasn't my initial
>> >> concern.
>> >>
>> >Why 32-bit is not enough?
>> >
>> >> > And instead of treating port_number as handle, there should be
>> >> > different attribute, is that the ask?
>> >>
>> >> Yes, the ask, as always, is to not abuse existing attributes to carry
>> >> tangentially related information.
>> >
>> >Why it is tangential?
>> >Devlink_port has got a port_number. Depending on flavour this port_number
>> represents a port.
>> >If it is floavour=PHYSICAL, its physical port number.
>> >If it is eswitch pf/vf ports, it represents eswitch port.
>> >
>> >Why you see it only as physical_port_number?
>> 
>> The original intention was like that. See the desc of
>> devlink_port_attrs_set():
>> 
>>  *      @port_number: number of the port that is facing user, for example
>>  *                    the front panel port number
>> 
>> For vf/pf representors, this is not applicable and should be indeed avoided.
>> 
>Physical port number is not applicable but this is useful information that completes the eswitch picture.
>Because eswitch has this termination end point anyway.

Use port_index. That is up to the driver to put whatever value there.


>Instead of inventing some new vendor specific field, I see value in using existing port_number field.
>Will wait for others inputs.
>
>> However, we expose it for DEVLINK_PORT_FLAVOUR_CPU and
>> DEVLINK_PORT_FLAVOUR_DSA. Not sure if it makes sense there either.
>> Ccing Florian, Andrew and Vivien.
>> What do you guys think?
>> 
>> Perhaps we should have:
>> 	if (attrs->flavour == DEVLINK_PORT_FLAVOUR_PHYSICAL &&
>> 	    nla_put_u32(msg, DEVLINK_ATTR_PORT_NUMBER, attrs-
>> >port_number))
>>                 return -EMSGSIZE;
>> in devlink_nl_port_attrs_put()
>