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Date: Tue, 16 Jan 2024 15:47:05 +0200
From: Vladimir Oltean <olteanv@gmail.com>
To: =?utf-8?B?QXLEsW7DpyDDnE5BTA==?= <arinc.unal@arinc9.com>
Cc: 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>,
	mithat.guner@xeront.com, erkin.bozoglu@xeront.com,
	Luiz Angelo Daros de Luca <luizluca@gmail.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [RFC PATCH net-next 6/8] net: dsa: mt7530: simplify
 mt7530_setup_port6() and change to void
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On Tue, Jan 16, 2024 at 04:09:18PM +0300, Arınç ÜNAL wrote:
> Do you mean by internal port that the port does not have MII pinout? Port 6
> of the MT7530 switch do. It is possible to have an external PHY wired to it.

Yes, this is what I meant by internal port. It seems I was wrong to
assume it is always connected to GMAC0.

How is the selection done between internal and external wiring?

If external wiring to a PHY is possible, shouldn't the driver accept all
4 RGMII variants with phy_interface_mode_is_rgmii(), because the delays
specified in "rgmii-txid", "rgmii-rxid", "rgmii-id" always pertain to
the PHY, and thus it doesn't make sense for the MAC to not allow the use
of the full spectrum?

> So it would make sense to design mt7530_setup_port6() in the sense that
> dynamic reconfiguration is possible.

Ok, you mean to keep the dynamic reconfiguration possible rather than
redesign to disallow it.

> I've tested to see that the core operations for TRGMII does not interfere
> so no need to undo them when the interface changes from TRGMII to RGMII.
> 
> I'll do below on this patch:
> 
> 	if (interface == PHY_INTERFACE_MODE_RGMII) {
> 		mt7530_rmw(priv, MT7530_P6ECR, P6_INTF_MODE_MASK,
> 			   P6_INTF_MODE(0));
> 		return;
> 	}

Ok.