netdev - Re: [PATCH net-next v2 0/5] TSN auto negotiation between 1G and 2.5G

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Message-ID: <ZQxZVbmdcAN6UI2G@shell.armlinux.org.uk>
Date: Thu, 21 Sep 2023 15:55:17 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Andrew Lunn <andrew@...n.ch>
Cc: Choong Yong Liang <yong.liang.choong@...ux.intel.com>,
	Rajneesh Bhardwaj <irenic.rajneesh@...il.com>,
	David E Box <david.e.box@...ux.intel.com>,
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	Mark Gross <markgross@...nel.org>,
	Jose Abreu <Jose.Abreu@...opsys.com>,
	Heiner Kallweit <hkallweit1@...il.com>,
	"David S . Miller" <davem@...emloft.net>,
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	Michael Sit Wei Hong <michael.wei.hong.sit@...el.com>,
	Lai Peter Jun Ann <jun.ann.lai@...el.com>
Subject: Re: [PATCH net-next v2 0/5] TSN auto negotiation between 1G and 2.5G

On Thu, Sep 21, 2023 at 04:41:20PM +0200, Andrew Lunn wrote:
> On Thu, Sep 21, 2023 at 03:12:19PM +0100, Russell King (Oracle) wrote:
> > On Thu, Sep 21, 2023 at 03:21:00PM +0200, Andrew Lunn wrote:
> > > > Hi Andrew,
> > > > 
> > > > After conducting a comprehensive study, it seems that implementing
> > > > out-of-band for all link modes might not be feasible. I may have missed some
> > > > key aspects during my analysis.
> > > > 
> > > > Would you be open to sharing a high-level idea of how we could potentially
> > > > make this feasible? Your insights would be greatly appreciated.
> > > 
> > > stmmac_mac_link_up() gets passed interface, speed and duplex. That
> > > tells you what the PHY has negotiated. Is there anything else you need
> > > to know?
> > 
> > The problem is... the stmmac driver is utter bollocks - that information
> > is *not* passed to the BSP. Instead, stmmac parse and store information
> > such as the PHY interface mode at initialisation time. BSPs also re-
> > parse and store e.g. the PHY interface mode at initialisation time.
> > The driver ignores what it gets from phylink.
> > 
> > The driver is basically utter crap. That's an area I _had_ patches to
> > clean up. I no longer do. stmmac is crap crap crap and will stay crap
> > until they become more receptive to patches to fix it, even if the
> > patches are not 100% to their liking but are in fact correct. Maybe
> > if I ever decide to touch that driver in the future. Which I doubt
> > given my recent experience.
> 
> Hi Russell
> 
> You pointed out the current proposal will break stuff. Do you see a
> way forward for this patchset which does not first involve actually
> cleaning up of this driver?

As I said in one of my replies, it would really help if the author can
provide a table showing what is attempting to be achieved here. With
that, we should be able to work out exactly what is required, what
needs to change in stmmac, etc.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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