linux-kernel - Re: [PATCH net-next] net: phy: intel-xway: workaround stale LEDs before link-up

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] [day] [month] [year] [list]

Message-ID: <aWmdMyJbzaoETETA@makrotopia.org>
Date: Fri, 16 Jan 2026 02:06:43 +0000
From: Daniel Golle <daniel@...rotopia.org>
To: Andrew Lunn <andrew@...n.ch>
Cc: Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Benny (Ying-Tsan) Weng" <yweng@...linear.com>,
	Avinash Jayaraman <ajayaraman@...linear.com>,
	Bing tao Xu <bxu@...linear.com>,
	Juraj Povazanec <jpovazanec@...linear.com>,
	"Fanni (Fang-Yi) Chan" <fchan@...linear.com>,
	"Livia M. Rosu" <lrosu@...linear.com>,
	John Crispin <john@...ozen.org>
Subject: Re: [PATCH net-next] net: phy: intel-xway: workaround stale LEDs
 before link-up

On Fri, Jan 16, 2026 at 02:23:18AM +0100, Andrew Lunn wrote:
> On Thu, Jan 15, 2026 at 11:40:38PM +0000, Daniel Golle wrote:
> > Due to a bug in some PHY internal firmware, manual control as well as
> > polarity configuration of the PHY LEDs has no effect until a link has
> > been detected at least once after reset. Apparently the LED control
> > thread is not started until then.
> > 
> > As a workaround, clear the BMCR_ANENABLE bit for 100ms to force the
> > firmware to start the LED thread, allowing manual LED control and
> > respecting LED polarity before the first link comes up.
> > 
> > In case the legacy default LED configuration is used the bug isn't
> > visible, so only apply the workaround in case LED configuration is
> > present in the device tree.
> 
> You should consider the case of forced links, where autoneg is
> disabled. Under such conditions, you should not leave autoneg enabled.

If BMCR_ANENABLE has already been disabled after a reset we can skip
this workaround entirely, as doing that once for more than 100ms is all
needed for the LEDs to work properly.

However, I'm not aware of .config_init ever being run again after the
intial attachment of the PHY and call to phy_init_hw().

All user-defined configuration happens after that, and would then remove
the BMCR_ANENABLE bit just like it would do it if it was set by the
hardware after reset.
(note that BMCR_ANENABLE is set as part of the reset value of BMCR on
this PHY)

But maybe I'm getting something wrong here?