netdev - RE: [PATCH iwl-next v2] ice: Disable Cage Max Power override

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Message-ID: <MW4PR11MB57766C3B9C05C94F51630251FDE7A@MW4PR11MB5776.namprd11.prod.outlook.com>
Date: Tue, 29 Aug 2023 09:12:22 +0000
From: "Drewek, Wojciech" <wojciech.drewek@...el.com>
To: Ido Schimmel <idosch@...sch.org>
CC: Jakub Kicinski <kuba@...nel.org>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "Kitszel, Przemyslaw"
	<przemyslaw.kitszel@...el.com>, "idosch@...dia.com" <idosch@...dia.com>
Subject: RE: [PATCH iwl-next v2] ice: Disable Cage Max Power override



> -----Original Message-----
> From: Ido Schimmel <idosch@...sch.org>
> Sent: niedziela, 27 sierpnia 2023 10:47
> To: Drewek, Wojciech <wojciech.drewek@...el.com>
> Cc: Jakub Kicinski <kuba@...nel.org>; intel-wired-lan@...ts.osuosl.org; netdev@...r.kernel.org; Kitszel, Przemyslaw
> <przemyslaw.kitszel@...el.com>; idosch@...dia.com
> Subject: Re: [PATCH iwl-next v2] ice: Disable Cage Max Power override
> 
> On Fri, Aug 25, 2023 at 11:01:07AM +0000, Drewek, Wojciech wrote:
> > CC: Ido
> >
> > > -----Original Message-----
> > > From: Jakub Kicinski <kuba@...nel.org>
> > > Sent: czwartek, 24 sierpnia 2023 17:32
> > > To: Drewek, Wojciech <wojciech.drewek@...el.com>
> > > Cc: intel-wired-lan@...ts.osuosl.org; netdev@...r.kernel.org; Kitszel, Przemyslaw <przemyslaw.kitszel@...el.com>
> > > Subject: Re: [PATCH iwl-next v2] ice: Disable Cage Max Power override
> > >
> > > On Thu, 24 Aug 2023 10:54:59 +0200 Wojciech Drewek wrote:
> > > > NVM module called "Cage Max Power override" allows to
> > > > change max power in the cage. This can be achieved
> > > > using external tools. The responsibility of the ice driver is to
> > > > go back to the default settings whenever port split is done.
> > > > This is achieved by clearing Override Enable bit in the
> > > > NVM module. Override of the max power is disabled so the
> > > > default value will be used.
> > >
> > > Can you say more? We have ETHTOOL_MSG_MODULE_GET / SET, sounds like
> > > something we could quite easily get ethtool to support?
> >
> > So you're suggesting that ethtool could support setting the maximum power in the cage?
> > Something like:
> >  - new "--set-module" parameter called "power-max"
> >  - new "--get-module" parameters: "power-max-allowed", "power-min-allowed" indicating limitations reported by the HW.
> >
> > About the patch itself, it's only about restoration of the default settings upon port split. Those might be overwritten by
> > Intel's external tools.
> 
> Can you please explain why this setting needs to be changed in the first
> place and why it needs to be restored to the default on port split?

In some cases users are trying to use media with power exceeding max allowed value.
Port split require system reboot so it feels natural to me to restore default settings.