linux-kernel - Re: [PATCH net v2] net: dsa: b53: bcm531x5: fix cpu rgmii mode interpretation

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Message-ID: <044303c3-03fa-4eea-8b63-f804171a4f93@broadcom.com>
Date: Fri, 7 Nov 2025 16:38:49 -0800
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Jonas Gorski <jonas.gorski@...il.com>, Andrew Lunn <andrew@...n.ch>,
 Vladimir Oltean <olteanv@...il.com>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, Álvaro Fernández Rojas
 <noltari@...il.com>
Subject: Re: [PATCH net v2] net: dsa: b53: bcm531x5: fix cpu rgmii mode
 interpretation

On 11/7/2025 12:30 AM, Jonas Gorski wrote:
> b53_adjust_531x5_rgmii() incorrectly enable delays in rgmii mode, but
> disables them in rgmii-id mode. Only rgmii-txid is correctly handled.
> 
> Fix this by correctly enabling rx delay in rgmii-rxid and rgmii-id
> modes, and tx delay in rgmii-txid and rgmii-id modes.
> 
> Since b53_adjust_531x5_rgmii() is only called for fixed-link ports,
> these are usually used as the CPU port, connected to a MAC. This means
> the chip is assuming the role of the PHY and enabling delays is
> expected.
> 
> Since this has the potential to break existing setups, treat rgmii
> as rgmii-id to keep the old broken behavior.
> 
> Fixes: 967dd82ffc52 ("net: dsa: b53: Add support for Broadcom RoboSwitch")
> Reported-by: Álvaro Fernández Rojas <noltari@...il.com>
> Signed-off-by: Jonas Gorski <jonas.gorski@...il.com>

Reviewed-by: Florian Fainelli <florian.fainelli@...adcom.com>
-- 
Florian