netdev - Re: [PATCH RFC net-next 00/15] net: stmmac: rk: cleanups galore

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aS3EfuypsaGK6Ww_@shell.armlinux.org.uk>
Date: Mon, 1 Dec 2025 16:38:22 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Andrew Lunn <andrew@...n.ch>
Cc: Heiner Kallweit <hkallweit1@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Heiko Stuebner <heiko@...ech.de>, Jakub Kicinski <kuba@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	Maxime Coquelin <mcoquelin.stm32@...il.com>, netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH RFC net-next 00/15] net: stmmac: rk: cleanups galore

On Mon, Dec 01, 2025 at 04:55:21PM +0100, Andrew Lunn wrote:
> > One of the interesting things is that this appears to deal with RGMII
> > delays at the MAC end of the link, but there's no way to tell phylib
> > that's the case. I've not looked deeply into what is going on there,
> > but it is surprising that the driver insists that the delays (in
> > register values?) are provided, but then ignores them depending on the
> > exact RGMII mode selected.
> 
> Yes, many Rockchip .dts files use phy-mode = 'rgmii', and then do the
> delays in the MAC. I've been pushing back on this for a while now, and
> in most cases, it is possible to set the delays to 0, and use
> 'rgmii-id'.
> 
> Unfortunately, the vendor version of the driver comes with a debugfs
> interface which puts the PHY into loopback, and then steps through the
> different delay values to find the range of values which result in no
> packet loss. The vendor documentation then recommends
> phy-mode='rgmii', and set the delays to the middle value for this
> range. So the vendor is leading developers up the garden path.
> 
> These delay values also appear to be magical. There has been at least
> one attempt to reverse engineer the values back to ns, but it was not
> possible to get consistent results across a collection of boards.

Oh yes, I remember that. I also remember that I had asked for the
re-use of "phy_power_on()" to be fixed:

https://lore.kernel.org/netdev/aDne1Ybuvbk0AwG0@shell.armlinux.org.uk/

but that never happened... which makes me wonder whether we *shouldn't*
have applied "sensor101"'s patch until such a requested patch was
available. In my experience, this is the standard behaviour - as a
reviewer, you ask a contributor to do something as part of their
patch submission, and as long as their patch gets merged, they
couldn't give a monkeys about your request.

So, in future, I'm going to take the attitude that I will NAK
contributions if I think there's a side issue that the contributor
should also be addressing until that side issue is addressed.

This shouldn't be necessary, I wish this weren't necessary, and I wish
people could be relied upon to do the right thing, but apparently it is
going to take a stick (not merging their patches) to get them to co-
operate. More fool me for trusting someone to do something.

I now have a couple of extra patches addressing my point raised in
that email... which I myself shouldn't have had to write.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!