Re: [PATCH] net: phy: intel-xway: workaround 100BASE-TX Link-Up issue

Thanks for the timely feedback, Andrew!

On Tue, 2026-09-15 at 14:37 +0200, Andrew Lunn wrote:

quoted

MaxLinear GSW12x/GSW14x Ethernet Switch Errata Sheet states:
"An issue has been sporadically observed after device power-on on the first
link-up attempt in 100BASE-TX mode resulting in either the link-up taking a
long time, or failing to link-up altogether...

Workaround:
After power-on, enable Cable Diagnostic Mode for all ports and disable
it..."

Implement the proposed workaround unconditionally in the Intel XWAY driver
(MaxLinear GSW1xx switches incorporate Intel XWAY PHYs) because the
diagnostic bits have the same meaning even in older integral PHYs such as
GPY111/PEF7071/PHY11G. So it's not clear how to distinguish the affected
newer integrated PHYs, but the workaround should not hurt the older PHYs.

Cc: stable@vger.kernel.org

Please set the Subject: line correctly to indicate net, and include a
Fixes: tag.

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html

Will fix in v2, sorry for that!

Out if interest, is there sufficient details in the data sheet to
implement cable diagnostics?

I'd say, no. I see no details on determining open/short circuit or cable
length, even though the datasheet claims the device supports it.

I've tried to activate Standard IEEE test patterns in the past, those
required for Ethernet compliance test -- it didn't work out of the box
and I've got no support on it from the vendor.

Same story with packet generator.

-- 
Alexander Sverdlin
Siemens AG
www.siemens.com