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Date:   Thu, 15 Jun 2023 00:50:49 +0300
From:   =?UTF-8?B?QXLEsW7DpyDDnE5BTA==?= <arinc.unal@arinc9.com>
To:     Vladimir Oltean <olteanv@gmail.com>
CC:     "Russell King (Oracle)" <linux@armlinux.org.uk>,
        Daniel Golle <daniel@makrotopia.org>,
        Landen Chao <Landen.Chao@mediatek.com>,
        DENG Qingfang <dqfext@gmail.com>,
        Sean Wang <sean.wang@mediatek.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Frank Wunderlich <frank-w@public-files.de>,
        Bartel Eerdekens <bartel.eerdekens@constell8.be>,
        mithat.guner@xeront.com, erkin.bozoglu@xeront.com,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org
Subject: Re: [PATCH net v4 5/7] net: dsa: mt7530: fix handling of LLDP frames
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On 15 June 2023 00:43:13 EEST, Vladimir Oltean <olteanv@gmail=2Ecom> wrote:
>On Wed, Jun 14, 2023 at 11:52:24PM +0300, Ar=C4=B1n=C3=A7 =C3=9CNAL wrote=
:
>> On 14=2E06=2E2023 19:42, Russell King (Oracle) wrote:
>> > On Mon, Jun 12, 2023 at 10:59:43AM +0300, arinc9=2Eunal@gmail=2Ecom w=
rote:
>> > > From: Ar=C4=B1n=C3=A7 =C3=9CNAL <arinc=2Eunal@arinc9=2Ecom>
>> > >=20
>> > > LLDP frames are link-local frames, therefore they must be trapped t=
o the
>> > > CPU port=2E Currently, the MT753X switches treat LLDP frames as reg=
ular
>> > > multicast frames, therefore flooding them to user ports=2E To fix t=
his, set
>> > > LLDP frames to be trapped to the CPU port(s)=2E
>
>so far so good
>
>> > >=20
>> > > The mt753x_bpdu_port_fw enum is universally used for trapping frame=
s,
>> > > therefore rename it and the values in it to mt753x_port_fw=2E
>
>yeah, this part of the patch is not useful at all [ here ]
>
>> > >=20
>> > > For MT7530, LLDP frames received from a user port will be trapped t=
o the
>> > > numerically smallest CPU port which is affine to the DSA conduit in=
terface
>> > > that is up=2E
>> > >=20
>> > > For MT7531 and the switch on the MT7988 SoC, LLDP frames received f=
rom a
>> > > user port will be trapped to the CPU port that is affine to the use=
r port
>> > > from which the frames are received=2E
>
>redundant and useless information here - what's important here is that
>they're trapped, not where

Ok, will remove=2E

>
>> > > The bit for R0E_MANG_FR is 27=2E When set, the switch regards the f=
rames with
>> > > :0E MAC DA as management (LLDP) frames=2E This bit is set to 1 afte=
r reset on
>> > > MT7530 and MT7531 according to the documents MT7620 Programming Gui=
de v1=2E0
>> > > and MT7531 Reference Manual for Development Board v1=2E0, so there'=
s no need
>> > > to deal with this bit=2E Since there's currently no public document=
 for the
>> > > switch on the MT7988 SoC, I assume this is also the case for this s=
witch=2E
>
>I guess that the reader who isn't familiar with the hardware will never
>get to ask himself "is the unrelated R0E_MANG_FR bit set ok?", and the
>familiar reader can just look that up in the programming guides that are
>available, and see the default value and that the driver doesn't change i=
t=2E
>
>So I just don't see how this bit of information is relevant in this
>patch=2E Sure, by all means, provide all context that helps the reader to
>understand the change, but at the same time: less is more=2E

Will remove=2E

>
>> > >=20
>> > > Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek M=
T7530 switch")
>> >=20
>> > Patch 4 claims to be a fix for this commit, and introduces one of the=
se
>> > modifications to MT753X_BPC, which this patch then changes=2E
>> >=20
>> > On the face of it, it seems this patch is actually a fix to patch 4 a=
s
>> > well as the original patch, so does that mean that patch 4 only half
>> > fixes a problem?
>>=20
>> I should do the enum renaming on my net-next series instead, as it's no=
t
>> useful to what this patch fixes at all=2E
>
>please do so (assuming that the enum really has to be changed)=2E
>
>also, if you're not really sure that this behavior has impacted any user
>(including yourself), I suppose there's also the option of fixing this in
>net-next as one of the earliest patches, independent from any other rewor=
k,
>so that in case there's a request to backport it to stable, it's possible=
=2E
>I remember having suggested this once already=2E

This impacts the devices of the company I work with and Bartel's, so I wou=
ld like this on the stable kernels immediately=2E

Ar=C4=B1n=C3=A7