netdev - Re: [PATCH v1 1/3] dt-bindings: net: dsa: microchip: add microchip,single-led-mode flag

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: <bg6t5lhnved4tvjz4zxt77hjvwp423tr77xlwbiebty45r3ry6@4eghzotqon6h>
Date: Tue, 3 Feb 2026 14:44:28 +0100
From: Heinrich Toews <ht@...-software.de>
To: Tim Harvey <tharvey@...eworks.com>
Cc: netdev <netdev@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>, 
	Florian Fainelli <f.fainelli@...il.com>, Vladimir Oltean <olteanv@...il.com>, 
	Rob Herring <robh+dt@...nel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Subject: Re: [PATCH v1 1/3] dt-bindings: net: dsa: microchip: add
 microchip,single-led-mode flag

Hi Tim,

On Fri, Jan 30, 2026 at 11:19:30AM -0800, Tim Harvey wrote:
> > Hi Andrew,
> >
> > > Am 28.01.26 um 16:22 schrieb Andrew Lunn:
> > > Is that really true? Generally, what actually happens is the
> > > configuration is left alone. So if the boot loader, for example, has
> > > set the configuration, that configuration is left unchanged. So it
> > > could actually be in single LED mode, not tri-colour.
> > >
> > Oh, you're right. We cannot assume a hardware reset state here.
> > Since the driver currently does not touch these registers, the configuration is indeed
> > "inherited" from the bootloader or the
> > hardware strapping.
> 
> Hi Heinrich,
> 
> The setting the SW_RESET bit of REG_SW_OPERATION in
> ksz9477_reset_switch() resets all switch registers so even when the
> mode/errata are taken care of in boot firmware that gets clobbered
> when Linux starts. It is not inherited.

You're right. I see that ksz_setup() always triggers a switch-reset and
there is no device tree property which could change this behaviour.

According to the datasheet (DS00002392C, p. 86), setting Bit 1 in 
REG_SW_OPERATION (0x0300) resets all internal registers, including 
PHY registers. So the switch indeed remains its default
"Tri-Color Dual-LED Mode" if microchip,single-led-mode property is not set.

> I have this switch with single-led mode on two of the boards I support
> (imx8mp-venice-gw74xx.dts and imx8mm-venice-gw7901.dts) and am
> interested in seeing your v2 of this series. Please add me to the cc
> if you would not mind.

Sure. I will add you to the CC for the v2 series. Thanks for the feedback!

Regards,
Heinrich.