linux-kernel - Re: [PATCH 4/4] net: stmmac: Add glue layer for Sophgo SG2044 SoC

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Message-ID: <amg64lxjjetkzo5bpi7icmsfgmt5e7jmu2z2h3duqy2jcloj7s@nma2hjk4so5b>
Date: Wed, 23 Oct 2024 15:21:36 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: Andrew Lunn <andrew@...n.ch>, Inochi Amaoto <inochiama@...il.com>
Cc: Chen Wang <unicorn_wang@...look.com>, 
	Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Inochi Amaoto <inochiama@...look.com>, Alexandre Torgue <alexandre.torgue@...s.st.com>, 
	Jose Abreu <joabreu@...opsys.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>, 
	Richard Cochran <richardcochran@...il.com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Giuseppe Cavallaro <peppe.cavallaro@...com>, Yixun Lan <dlan@...too.org>, netdev@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-stm32@...md-mailman.stormreply.com, linux-arm-kernel@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 4/4] net: stmmac: Add glue layer for Sophgo SG2044 SoC

On Wed, Oct 23, 2024 at 03:08:52AM +0200, Andrew Lunn wrote:
> On Wed, Oct 23, 2024 at 08:41:36AM +0800, Inochi Amaoto wrote:
> > On Tue, Oct 22, 2024 at 03:51:08PM +0200, Andrew Lunn wrote:
> > > On Tue, Oct 22, 2024 at 06:21:49PM +0800, Inochi Amaoto wrote:
> > > > On Mon, Oct 21, 2024 at 03:27:18PM +0200, Andrew Lunn wrote:
> > > > > > It is related to the RGMII delay. On sg2044, when the phy 
> > > > > > sets rx-delay, the interal mac is not set the same delay, 
> > > > > > so this is needed to be set.
> > > > > 
> > > > > This is the wrong way to do it. Please look at how phy-mode should be
> > > > > used, the four different "rgmii" values. Nearly everybody gets this
> > > > > wrong, so there are plenty of emails from me in the netdev list about
> > > > > how it should be done.
> > > > > 
> > > > 
> > > > The phy-mode is alreay set to the "rgmii-id" and a rx delay is already
> > > > set (a default tx delay is set by the phy driver). In the scenario 
> > > > the extra bit is used to fix 2ns difference between the sampling clock
> > > > and data. It is more like an extra setting and the kernel can not handle
> > > > it by only setting the phy-mode.
> > > 
> > > This sounds wrong.
> > > 
> > > So in DT you have rgmii-id? You say the PHY is doing TX delay. So you
> > > pass PHY_INTERFACE_MODE_RGMII_TXID to the PHY? It is not clear from
> > > this patch, i don't see any code mentioning
> > > PHY_INTERFACE_MODE_RGMII_TXID. Could you point me at that code.
> > > 
> > > 	Andrew
> > 
> > The phy on the board I have is YT8531, The config code is here:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/phy/motorcomm.c#n868
> 
> This PHY should be able to do rgmii-id, so there is no need for the
> MAC to add delays. We encourage that setup in linux, so all RGMII
> MAC/PHY pairs are the same, the PHY add the delays.
> 

Yes, this is what I have done at the beginning. At first I only
set up the phy setting and not set the config in the syscon. 
But I got a weird thing: the phy lookback test is timeout. 
Although the datasheet told it just adds a internal delay for 
the phy, I suspect sophgo does something more to set this delay.

Regards,
Inochi