linux-kernel - Re: [PATCH net-next] net: dsa: mt7530: fix support for MT7531BE

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Message-ID: <ZDW4Tr4bIGcxwDgs@makrotopia.org>
Date:   Tue, 11 Apr 2023 20:43:10 +0100
From:   Daniel Golle <daniel@...rotopia.org>
To:     Arınç ÜNAL <arinc.unal@...nc9.com>
Cc:     netdev@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Russell King <linux@...linux.org.uk>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Vladimir Oltean <olteanv@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH net-next] net: dsa: mt7530: fix support for MT7531BE

On Tue, Apr 11, 2023 at 10:30:06PM +0300, Arınç ÜNAL wrote:
> On 11.04.2023 03:11, Daniel Golle wrote:
> > There are two variants of the MT7531 switch IC which got different
> > features (and pins) regarding port 5:
> >   * MT7531AE: SGMII/1000Base-X/2500Base-X SerDes
> >   * MT7531BE: RGMII
> > 
> > Moving the creation of the SerDes PCS from mt753x_setup to mt7530_probe
> > with commit 6de285229773 ("net: dsa: mt7530: move SGMII PCS creation to
> > mt7530_probe function") works fine for MT7531AE which got two instances
> > of mtk-pcs-lynxi, however, MT7531BE requires mt7531_pll_setup to setup
> > clocks before the single PCS on port 6 (usually used as CPU port)
> > starts to work and hence the PCS creation failed on MT7531BE.
> > 
> > Fix this by introducing a pointer to mt7531_create_sgmii function in
> > struct mt7530_priv and call it again at the end of mt753x_setup like it
> > was before commit 6de285229773 ("net: dsa: mt7530: move SGMII PCS
> > creation to mt7530_probe function").
> 
> If I understand correctly, this patch does two things.
> 
> Run mt7531_create_sgmii() from mt753x_setup(), after mt7531_setup() and
> mt7531_setup_common() is run so that PCS on MT7531BE works.

> 
> Run the PCS creation code inside the loop only once if
> mt7531_dual_sgmii_supported() is false so it doesn't set the nonexistent
> port 5 SGMII on MT7531BE.

Yes, both is correct.

> 
> Regarding the first part:
> I was actually in the middle of moving the code until after
> mt7530_pll_setup() and mt7531_pll_setup() on mt7530_setup() and
> mt7531_setup() to mt7530_probe(). To me it makes more sense to run them on
> mt7530_probe() as there's a good amount of duplicate code on mt7530_setup()
> and mt7531_setup().

I thought about doing that as well, however, note that you will have to
move all the reset and regulator setup procedure to mt7530_probe() as
well then, as PLL setup currently happens after that, and that's
probably for a reason.

As the reset and regulator setup works differently on MT7530 and
MT7531, and depending on whether it's a standalone IC package or MCM, I
believe changes unifying this will have to be tested on a lot of
boards...

> 
> This will resolve the problem here, and make my future work regarding the
> PHY muxing feature on the MT7530 switch possible to do.
> 
> Regarding the second part:
> I'll take your changes to my current RFC patch series while addressing
> Jesse's suggestion if this is fine by you.

Yes, I'd appreciate that and I'm ready to test and review once you post
your updated series.