linux-kernel - Re: [PATCH net] net: pse-pd: Fix enabled status mismatch

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Message-ID: <20241002144656.31e59f0e@kmaincent-XPS-13-7390>
Date: Wed, 2 Oct 2024 14:46:56 +0200
From: Kory Maincent <kory.maincent@...tlin.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, Kyle Swenson <kyle.swenson@....tech>,
 thomas.petazzoni@...tlin.com, Oleksij Rempel <o.rempel@...gutronix.de>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH net] net: pse-pd: Fix enabled status mismatch

On Wed, 2 Oct 2024 14:38:19 +0200
Andrew Lunn <andrew@...n.ch> wrote:

> On Wed, Oct 02, 2024 at 02:17:05PM +0200, Kory Maincent wrote:
> > PSE controllers like the TPS23881 can forcefully turn off their
> > configuration state. In such cases, the is_enabled() and get_status()
> > callbacks will report the PSE as disabled, while admin_state_enabled
> > will show it as enabled. This mismatch can lead the user to attempt
> > to enable it, but no action is taken as admin_state_enabled remains set.
> > 
> > The solution is to disable the PSE before enabling it, ensuring the
> > actual status matches admin_state_enabled.
> > 
> > Fixes: d83e13761d5b ("net: pse-pd: Use regulator framework within PSE
> > framework") Signed-off-by: Kory Maincent <kory.maincent@...tlin.com>
> > ---
> > 
> > FYI: Saving the enabled state in the driver is not a viable solution, as a
> > reboot may cause a mismatch between the real and software-saved states.  
> 
> This seems O.K. to me.
> 
> I'm assuming the controller has turned the configuration state to off
> to stop the magic smoke escaping? Is there any sort of notification of
> this?  Does it raise an interrupt? Sometime in the future we might
> want to add a netlink notification about this?

Thanks for your review!

Yes, in case of over-current or over-temperature, there is an interrupt. The
netlink notifications support will arrive soon in the series in progress.

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