linux-kernel - Re: [PATCH RFC net-next v3 21/27] net: pse-pd: Add support for getting and setting port priority

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Message-ID: <20241127120043.481bf0a2@kmaincent-XPS-13-7390>
Date: Wed, 27 Nov 2024 12:00:43 +0100
From: Kory Maincent <kory.maincent@...tlin.com>
To: Oleksij Rempel <o.rempel@...gutronix.de>
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>, Liam Girdwood
 <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>, linux-kernel@...r.kernel.org,
 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>
Subject: Re: [PATCH RFC net-next v3 21/27] net: pse-pd: Add support for
 getting and setting port priority

On Wed, 27 Nov 2024 11:31:18 +0100
Oleksij Rempel <o.rempel@...gutronix.de> wrote:

> On Wed, Nov 27, 2024 at 11:11:26AM +0100, Kory Maincent wrote:
> > On Wed, 27 Nov 2024 10:30:43 +0100
> > Oleksij Rempel <o.rempel@...gutronix.de> wrote:
> >   
> > > On Tue, Nov 26, 2024 at 04:52:28PM +0100, Kory Maincent wrote:  
>  [...]  
>  [...]  
> > >  [...]  
> > >  [...]    
>  [...]  
> > > 
> > > Good question :)
> > >   
>  [...]  
> > > 
> > > And a way to upload everything in atomic way, but I see it as
> > > optimization and can be done separately
> > >   
>  [...]  
> > > 
> > > Both can be implemented for TI. By constantly polling the channel
> > > current register, it should be possible to implement dynamic strategy.
> > >   
>  [...]  
> > > 
> > > Use hard coded one ¯\_(ツ)_/¯  
> > 
> > I think we could start with disabled disconnection policy for now.
> > The user cans still play with the priority value which is really reasonable
> > as there is as many priority values as PSE ports in the static strategy.  
> 
> Hm, since prios without disconnecting do not make sens and it looks more like
> all disconnection policies are optimizations steps for configurations with
> multiple ports having same prio, i would suggest an implementation where
> no same prios are allowed on multiple ports.

This won't allow users that don't care about priorities.

I think as we support only budget strategy for now. On the case of power budget
exceeded we should disconnect all the ports that are on the lowest priority
until we get enough power. If there is no ports with a lower priority than the
newly connected we should not power on the newly connected.

With my proposition, at boot as all the ports have the same priority it is like
we don't care about priority.

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