Message-ID: <20250303144051.2503fb43@kmaincent-XPS-13-7390>
Date: Mon, 3 Mar 2025 14:40:51 +0100
From: Kory Maincent <kory.maincent@...tlin.com>
To: Oleksij Rempel <o.rempel@...gutronix.de>
Cc: Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>, "David
 S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo
 Abeni <pabeni@...hat.com>, Jonathan Corbet <corbet@....net>, Donald Hunter
 <donald.hunter@...il.com>, Rob Herring <robh@...nel.org>, Andrew Lunn
 <andrew+netdev@...n.ch>, Simon Horman <horms@...nel.org>, Heiner Kallweit
 <hkallweit1@...il.com>, Russell King <linux@...linux.org.uk>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Thomas
 Petazzoni <thomas.petazzoni@...tlin.com>, netdev@...r.kernel.org,
 linux-doc@...r.kernel.org, Kyle Swenson <kyle.swenson@....tech>, Dent
 Project <dentproject@...uxfoundation.org>, kernel@...gutronix.de, Maxime
 Chevallier <maxime.chevallier@...tlin.com>, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v5 06/12] net: pse-pd: Add support for budget
 evaluation strategies

On Sat, 1 Mar 2025 14:00:43 +0100
Oleksij Rempel <o.rempel@...gutronix.de> wrote:

> On Thu, Feb 27, 2025 at 07:26:40PM +0100, Kory Maincent wrote:
> > On Thu, 27 Feb 2025 17:40:42 +0100
> > Oleksij Rempel <o.rempel@...gutronix.de> wrote:

> > > I would prefer to have it in the for of devlink or use regulator netlink
> > > interface. But, we do not need to do this discussion right now.  
> > 
> > If we want to report the method we should discuss it now. We shouldn't add
> > BUDGET_EVAL_STRAT uAPI to ethtool if we use another way to get and set the
> > method later.  
> 
> Ok, I assume we are talking about different things. I mean - not port
> specific configurations and diagnostic, will have different interface.
> 
> BUDGET_EVAL_STRAT is port specific. HP and Cisco implement it as port
> specific. PD692x0 Protocol manual describe it as port specific too:
> 3.3.6 Set BT Port Parameters
>  Bits [3..0]—BT port PM mode
>   0x0: The port power that is used for power management purposes is
>        dynamic (Iport x Vmain).
>   0x1: The port power that is used for power management purposes is port
>        TPPL_BT.
>   0x2: The port power that is used for power management purposes is
>        dynamic for non LLDP/CDP/Autoclass ports and TPPL_BT for
> LLDP/CDP/Autoclass ports. 0xF: Do not change settings.

I don't really understand how that can be port specific when the power budget is
per PD69208 manager. Maybe I am missing information here.

> > We could also not report the method for now and assume the user knows it for
> > the two controllers currently supported.  
> 
> On one side: it is not just status, but also active configuration. By
> implementing the interface we may break default configuration and user
> expectations.

Yes we should not implement the budget method get/set interface in this series.
 
> On other side: PD692x0 seems to need more then just setting prios to
> manage them correctly. For example power bank limits should be set,
> otherwise internal firmware won't be able to perform budget calculations.

Patch 8 is already configuring the power PD692x0 bank limit according to PSE
power domain budget.

> So, I assume, critical components are missing anyway.

As we are not supporting the budget method configured by the user in this
series, I agreed we should not add any uAPI related to it that could be broken
or confusing later.

I will remove it and send v6.

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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