Subject: Re: [PATCH] net: dsa: mv88e6xxx: force cmode write on 6141/6341

From: Andrew Lunn <[email-masked]>
Date: Thu, 2 Jan 2020 23:36:41 +0100

On Thu, Jan 02, 2020 at 12:45:56PM -0800, David Miller wrote:
> From: Baruch Siach <[email-masked]>
> Date: Thu, 19 Dec 2019 11:48:22 +0200
> 
> > mv88e6xxx_port_set_cmode() relies on cmode stored in struct
> > mv88e6xxx_port to skip cmode update when the requested value matches the
> > cached value. It turns out that mv88e6xxx_port_hidden_write() might
> > change the port cmode setting as a side effect, so we can't rely on the
> > cached value to determine that cmode update in not necessary.
> > 
> > Force cmode update in mv88e6341_port_set_cmode(), to make
> > serdes configuration work again. Other mv88e6xxx_port_set_cmode()
> > callers keep the current behaviour.
> > 
> > This fixes serdes configuration of the 6141 switch on SolidRun Clearfog
> > GT-8K.
> > 
> > Fixes: 7a3007d22e8 ("net: dsa: mv88e6xxx: fully support SERDES on Topaz family")
> > Reported-by: Denis Odintsov <[email-masked]>
> > Signed-off-by: Baruch Siach <[email-masked]>
> 
> This thread has stalled on December 20th with Baruch asking if we can put this
> in for now as a temporary fix that solves the given problem whilst a better
> long term analysis and change is being worked on.

Hi David

It seems like a reasonable fix for the moment.

Reviewed-by: Andrew Lunn <[email-masked]>

    Andrew