netdev - Re: [RFC net-next 1/2] net: ethtool: plumb PHY stats to PHY drivers

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Message-ID: <20240904092024.530c54c3@fedora.home>
Date: Wed, 4 Sep 2024 09:20:24 +0200
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
 pabeni@...hat.com, Vladimir Oltean <olteanv@...il.com>, andrew@...n.ch,
 hkallweit1@...il.com, linux@...linux.org.uk, woojung.huh@...rochip.com,
 o.rempel@...gutronix.de
Subject: Re: [RFC net-next 1/2] net: ethtool: plumb PHY stats to PHY drivers

Hi Jakub,

On Fri, 30 Aug 2024 11:30:47 -0700
Jakub Kicinski <kuba@...nel.org> wrote:

> On Fri, 30 Aug 2024 10:16:30 +0200 Maxime Chevallier wrote:
> > > +static void
> > > +ethtool_get_phydev_stats(struct net_device *dev,
> > > +			 struct linkstate_reply_data *data)
> > > +{
> > > +	struct phy_device *phydev = dev->phydev;    
> > 
> > This would be a very nice spot to use the new
> > ethnl_req_get_phydev(), if there are multiple PHYs on that device.
> > Being able to access the stats individually can help
> > troubleshoot HW issues.
> >   
> > > +static void
> > > +ethtool_get_phydev_stats(struct net_device *dev, struct stats_reply_data *data)
> > > +{
> > > +	struct phy_device *phydev = dev->phydev;    
> > 
> > Here as well, but that's trickier, as the MAC can override the PHY
> > stats, but it doesn't know which PHY were getting the stats from.
> > 
> > Maybe we could make so that when we pass a phy_index in the netlink
> > command, we don't allow the mac to override the phy stats ? Or better,
> > don't allow the mac to override these stats and report the MAC-reported
> > PHY stats alongside the PHY-reported stats ?  
> 
> Maybe we can flip the order of querying regardless of the PHY that's
> targeted? Always query the MAC first and then the PHY, so that the
> PHY can override. Presumably the PHY can always provide more detailed
> stats than the MAC (IOW if it does provide stats they will be more
> accurate).

I think that could work indeed, good point.

[...]

> > I'm all in for getting the PHY stats from netlink though :)  
> 
> Great! FWIW I'm not sure what the status of these patches is.
> I don't know much about PHYs.
> I wrote them to help Oleksij out with the "netlink parts".
> I'm not sure how much I convinced Andrew about the applicability.
> And I don't know if this is enough for Oleksij to take it forward.
> So in the unlikely even that you have spare cycles and a PHY you can
> test with, do not hesitate to take these, rework, reset the author 
> and repost... :)

I do have some hardware I can test this on, and I'm starting to get
familiar with netlink :) I can give it a try, however I can't guarantee
as of right now that I'll be able to send anything before net-next
closes. I'll ping here if I start moving forward with this :)

Thanks,

Maxime