Date:   Thu, 2 Mar 2023 12:00:22 +0200
From:   Vladimir Oltean <olteanv@gmail.com>
To:     Daniel Golle <daniel@makrotopia.org>
Cc:     devicetree@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        netdev@vger.kernel.org, linux-mediatek@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Russell King <linux@armlinux.org.uk>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Mark Lee <Mark-MC.Lee@mediatek.com>,
        John Crispin <john@phrozen.org>, Felix Fietkau <nbd@nbd.name>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        DENG Qingfang <dqfext@gmail.com>,
        Landen Chao <Landen.Chao@mediatek.com>,
        Sean Wang <sean.wang@mediatek.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Jianhui Zhao <zhaojh329@gmail.com>,
        =?utf-8?B?QmrDuHJu?= Mork <bjorn@mork.no>
Subject: Re: [RFC PATCH v11 08/12] net: ethernet: mtk_eth_soc: fix RX data
 corruption issue
Message-ID: <20230302100022.vcw5kqpiy6jpmq3r@skbuf>
References: <cover.1677699407.git.daniel@makrotopia.org>
 <9a788bb6984c836e63a7ecbdadff11a723769c37.1677699407.git.daniel@makrotopia.org>
 <20230301233121.trnzgverxndxgunu@skbuf>
 <Y//n4R2QuWvySDbg@makrotopia.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <Y//n4R2QuWvySDbg@makrotopia.org>
Precedence: bulk

On Thu, Mar 02, 2023 at 12:03:45AM +0000, Daniel Golle wrote:
> On Thu, Mar 02, 2023 at 01:31:21AM +0200, Vladimir Oltean wrote:
> > On Wed, Mar 01, 2023 at 07:55:05PM +0000, Daniel Golle wrote:
> > > Also set bit 12 which disabled the RX FIDO clear function when setting up
> > > MAC MCR, as MediaTek SDK did the same change stating:
> > > "If without this patch, kernel might receive invalid packets that are
> > > corrupted by GMAC."[1]
> > > This fixes issues with <= 1G speed where we could previously observe
> > > about 30% packet loss while the bad packet counter was increasing.
> > > 
> > > [1]: https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/d8a2975939a12686c4a95c40db21efdc3f821f63
> > > Tested-by: Bj?rn Mork <bjorn@mork.no>
> > > Signed-off-by: Daniel Golle <daniel@makrotopia.org>
> > > ---
> > 
> > Should this patch be submitted separately from the series, to the
> > net.git tree, to be backported to stable kernels?
> 
> Maybe yes, as this issue may affect e.g. the BPi-R3 board when used
> with 1G SFP modules. Previously this has just never been a problem as
> all practically all boards with MediaTek SoCs using SGMII also use the
> MediaTek MT7531 switch connecting in 2500Base-X mode.
> 
> Should the Fixes:-tag hence reference the commit adding support for the
> BPi-R3?

If it's not an issue that affects existing setups, there is no need to
backport the patch. But it needs to be clearly described as such in the
commit message.

You mention <= 1G speeds, but then only talk about 1G SFP modules.
I see that the mtk_eth_soc driver also sets "gmii" and "rgmii" in
phylink's supported_interfaces. Those are also <= 1G speeds. There could
also be SGMII on-board PHYs. Does the RX FIFO clearing issue not affect
those?