linux-kernel - Re: [PATCH net-next v5 07/12] net: ethtool: Add PSE new budget evaluation strategy support feature

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Message-ID: <Z7iEYQzsdpUFmfZE@pengutronix.de>
Date: Fri, 21 Feb 2025 14:49:21 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Kory Maincent <kory.maincent@...tlin.com>
Cc: Andrew Lunn <andrew@...n.ch>, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, 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 07/12] net: ethtool: Add PSE new budget
 evaluation strategy support feature

Hi Kory,

On Tue, Feb 18, 2025 at 05:19:11PM +0100, Kory Maincent wrote:
> From: Kory Maincent (Dent Project) <kory.maincent@...tlin.com>
> 
> This patch expands the status information provided by ethtool for PSE c33
> with current port priority and max port priority. It also adds a call to
> pse_ethtool_set_prio() to configure the PSE port priority.

Thank you! Here are some comments...

> --- a/Documentation/networking/ethtool-netlink.rst
> +++ b/Documentation/networking/ethtool-netlink.rst
> @@ -1790,6 +1790,12 @@ Kernel response contents:
>    ``ETHTOOL_A_C33_PSE_PW_LIMIT_RANGES``       nested  Supported power limit
>                                                        configuration ranges.
>    ``ETHTOOL_A_PSE_PW_D_ID``                      u32  Index of the PSE power domain
> +  ``ETHTOOL_A_C33_PSE_BUDGET_EVAL_STRAT``        u32  Budget evaluation strategy
> +                                                      of the PSE
> +  ``ETHTOOL_A_C33_PSE_PRIO_MAX``                 u32  Priority maximum configurable
> +                                                      on the PoE PSE
> +  ``ETHTOOL_A_C33_PSE_PRIO``                     u32  Priority of the PoE PSE
> +                                                      currently configured

Please remove _C33_ from these fields, as they are not specific to Clause 33.

>    ==========================================  ======  =============================
>  
>  When set, the optional ``ETHTOOL_A_PODL_PSE_ADMIN_STATE`` attribute identifies
> @@ -1866,6 +1872,51 @@ equal.
>  The ``ETHTOOL_A_PSE_PW_D_ID`` attribute identifies the index of PSE power
>  domain.
>  
> +When set, the optional ``ETHTOOL_A_C33_PSE_PRIO_SUPP_MODES`` attribute
> +identifies the priority mode supported by the C33 PSE.
> +When set, the optional ``ETHTOOL_A_C33_PSE_BUDGET_EVAL_STRAT`` attributes is used to
> +identifies the currently configured C33 PSE budget evaluation strategy.
> +The available strategies are:
> +
> +1. Disabled:
> +
> +   In this mode, the port is excluded from active budget evaluation. It
> +   allows the port to violate the budget and is intended primarily for testing
> +   purposes.
> +
> +2. Static Method:
> +
> +   This method involves distributing power based on PD classification. It’s
> +   straightforward and stable, with the PSE core keeping track of the budget
> +   and subtracting the power requested by each PD’s class. This is the
> +   safest option and should be used by default.
> +
> +   Advantages: Every PD gets its promised power at any time, which guarantees
> +   reliability.
> +
> +   Disadvantages: PD classification steps are large, meaning devices request
> +   much more power than they actually need. As a result, the power supply may
> +   only operate at, say, 50% capacity, which is inefficient and wastes money.
> +
> +3. Dynamic Method:
> +
> +   This method monitors the current consumption per port and subtracts it from
> +   the available power budget. When the budget is exceeded, lower-priority
> +   ports are shut down. This method is managed by the PSE controller itself.
> +
> +   Advantages: This method optimizes resource utilization, saving costs.
> +
> +   Disadvantages: Low-priority devices may experience instability.
> +
> +.. kernel-doc:: include/uapi/linux/ethtool.h
> +    :identifiers: ethtool_pse_budget_eval_strategies
> +
> +When set, the optional ``ETHTOOL_A_C33_PSE_PRIO_MAX`` attribute identifies
> +the C33 PSE maximum priority value.
> +When set, the optional ``ETHTOOL_A_C33_PSE_PRIO`` attributes is used to
> +identifies the currently configured C33 PSE priority.
> +For a description of PSE priority attributes, see ``PSE_SET``.
> +
>  PSE_SET
>  =======
>  
> @@ -1879,6 +1930,8 @@ Request contents:
>    ``ETHTOOL_A_C33_PSE_ADMIN_CONTROL``        u32  Control PSE Admin state
>    ``ETHTOOL_A_C33_PSE_AVAIL_PWR_LIMIT``      u32  Control PoE PSE available
>                                                    power limit
> +  ``ETHTOOL_A_C33_PSE_PRIO``                 u32  Control priority of the
> +                                                  PoE PSE

Please remove _C33_ from these field, as they are not specific to
Clause 33.
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