netdev - Re: [PATCH net-next] net: dsa: mv88e6xxx: 6352: parse VTU data before loading STU data

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Message-ID: <20201111152732.6328f5be@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Wed, 11 Nov 2020 15:27:32 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Tobias Waldekranz <tobias@...dekranz.com>
Cc:     davem@...emloft.net, andrew@...n.ch, vivien.didelot@...il.com,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: dsa: mv88e6xxx: 6352: parse VTU data
 before loading STU data

On Sun,  8 Nov 2020 23:38:10 +0100 Tobias Waldekranz wrote:
> On the 6352, doing a VTU GetNext op, followed by an STU GetNext op
> will leave you with both the member- and state- data in the VTU/STU
> data registers. But on the 6097 (which uses the same implementation),
> the STU GetNext will override the information gathered from the VTU
> GetNext.
> 
> Separate the two stages, parsing the result of the VTU GetNext before
> doing the STU GetNext.
> 
> We opt to update the existing implementation for all applicable chips,
> as opposed to creating a separate callback for 6097. Though the
> previous implementation did work for (at least) 6352, the datasheet
> does not mention the masking behavior.
> 
> Signed-off-by: Tobias Waldekranz <tobias@...dekranz.com>
> ---
> 
> I was not sure if I should have created a separate callback, but I
> have not found any documentation that suggests that you can expect the
> STU GetNext op to mask the bits that are used to store VTU membership
> information in the way that 6352 does. So depending on undocumented
> behavior felt like something we would want to get rid of anyway.
> 
> Tested on 6097F and 6352.

I'm unclear what this fixes. What functionality is broken on 6097?
Can we identify the commit for a fixes tag?