Re: [PATCH net-next v3] net: dsa: realtek: rtl8366rb: Fix up port isolation

[Jakub Kicinski <kuba@kernel.org>]

On Sat, 25 Jul 2026 15:46:21 +0200 Linus Walleij wrote:
> Sashiko reports that we incorrectly disable isolation in the setup
> loop while what we want to do is to enable it.
> 
> Enable it by setting all isolation bits in the isolation mask
> for all ports in the switch.
> 
> Fix up the comments so it is clear what is going on, including a
> missing word in the helper function.

Sorry to report that both Sashikos remain skeptical.

https://sashiko.dev/#/patchset/20260725-rtl8366rb-fixes-v3-1-57557b39aaa5@kernel.org
https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260725-rtl8366rb-fixes-v3-1-57557b39aaa5@kernel.org

The mask is the allowed mask so the write of 0 was correct,
but we want EN + mask(0) ? The problem being that
rtl8366rb_port_set_isolation() does:

 if (mask)
	reg |= EN

so with mask of 0 we can't enable.

Maybe pass 

	rtl8366rb_port_set_isolation(priv, dp->index, BIT(dp->index));

?

Of course neither I nor the LLMs actually know this HW :S
But comments on other calls to rtl8366rb_port_set_isolation()
suggest that indeed the mask is for allowed ports.