Re: [PATCH v3 net-next] net: dsa: ksz_common: Allow only up to two HSR HW offloaded ports for KSZ9477

[Florian Fainelli <f.fainelli@gmail.com>]

On 6/19/2024 3:58 PM, Lukasz Majewski wrote:
> The KSZ9477 allows HSR in-HW offloading for any of two selected ports.
> This patch adds check if one tries to use more than two ports with
> HSR offloading enabled.
> 
> The problem is with RedBox configuration (HSR-SAN) - when configuring:
> ip link add name hsr0 type hsr slave1 lan1 slave2 lan2 interlink lan3 \
> 	supervision 45 version 1
> 
> The lan1 (port0) and lan2 (port1) are correctly configured as ports, which
> can use HSR offloading on ksz9477.
> 
> However, when we do already have two bits set in hsr_ports, we need to
> return (-ENOTSUPP), so the interlink port (lan3) would be used with
> SW based HSR RedBox support.
> 
> Otherwise, I do see some strange network behavior, as some HSR frames are
> visible on non-HSR network and vice versa.
> 
> This causes the switch connected to interlink port (lan3) to drop frames
> and no communication is possible.
> 
> Moreover, conceptually - the interlink (i.e. HSR-SAN port - lan3/port2)
> shall be only supported in software as it is also possible to use ksz9477
> with only SW based HSR (i.e. port0/1 -> hsr0 with offloading, port2 ->
> HSR-SAN/interlink, port4/5 -> hsr1 with SW based HSR).
> 
> Fixes: 5055cccfc2d1 ("net: hsr: Provide RedBox support (HSR-SAN)")
> Signed-off-by: Lukasz Majewski <lukma@denx.de>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>

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