Re: [PATCH RFC net-next 4/4] net: mtk_eth_soc: note interface modes not set in supported_interfaces

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Daniel Golle <daniel@makrotopia.org>
Cc: Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
	Sean Wang <sean.wang@mediatek.com>,
	Mark Lee <Mark-MC.Lee@mediatek.com>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	"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>,
	netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH RFC net-next 4/4] net: mtk_eth_soc: note interface modes not set in supported_interfaces
Date: Tue, 7 Mar 2023 14:04:59 +0000	[thread overview]
Message-ID: <ZAdEi2TsIw8Vjsh8@shell.armlinux.org.uk> (raw)
In-Reply-To: <ZAc7Q4VMzLjzQbRC@makrotopia.org>

On Tue, Mar 07, 2023 at 01:25:23PM +0000, Daniel Golle wrote:
> A quick grep through the device trees of the more than 650 ramips and
> mediatek boards we support in OpenWrt has revealed that *none* of them
> uses either reduced-MII or reverse-MII PHY modes. I could imaging that
> some more specialized ramips boards may use the RMII 100M PHY mode to
> connect with exotic PHYs for industrial or automotive applications
> (think: for 100BASE-T1 PHY connected via RMII). I have never seen or
> touched such boards, but there are hints that they do exist.
> 
> For reverse-MII there are cases in which the Ralink SoC (Rt305x, for
> example) is used in iNIC mode, ie. connected as a PHY to another SoC,
> and running only a minimal firmware rather than running Linux. Due to
> the lack of external DRAM for the Ralink SoC on this kind of boards,
> the Ralink SoC there will anyway never be able to boot Linux.
> I've seen this e.g. in multimedia devices like early WiFi-connected
> not-yet-so-smart TVs.
> 
> Tl;dr: I'd drop them. If anyone really needs them, it would be easy to
> add them again and then also add them to the phylink capability mask.

Thanks! That seems to be well reasoned. Would you have any objection to
using the above as part of the commit message removing these modes?

-- 
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