netdev - Re: [PATCH net-next v2 3/3] net: stmmac: Add glue layer for Spacemit K3 SoC

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Message-ID: <aXFVAoChTPZhjnGu@inochi.infowork>
Date: Thu, 22 Jan 2026 06:37:12 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: Andrew Lunn <andrew@...n.ch>, 
	"Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Inochi Amaoto <inochiama@...il.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>, Yixun Lan <dlan@...too.org>, 
	Maxime Coquelin <mcoquelin.stm32@...il.com>, Alexandre Torgue <alexandre.torgue@...s.st.com>, 
	Richard Cochran <richardcochran@...il.com>, Paul Walmsley <pjw@...nel.org>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, Yao Zi <ziyao@...root.org>, 
	Yanteng Si <siyanteng@...oftware.com.cn>, Vladimir Oltean <vladimir.oltean@....com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>, Chen-Yu Tsai <wens@...nel.org>, 
	Choong Yong Liang <yong.liang.choong@...ux.intel.com>, Shangjuan Wei <weishangjuan@...incomputing.com>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Boon Khai Ng <boon.khai.ng@...era.com>, 
	Maxime Chevallier <maxime.chevallier@...tlin.com>, Quentin Schulz <quentin.schulz@...rry.de>, 
	Giuseppe Cavallaro <peppe.cavallaro@...com>, Jose Abreu <joabreu@...opsys.com>, netdev@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	spacemit@...ts.linux.dev, linux-stm32@...md-mailman.stormreply.com, 
	linux-arm-kernel@...ts.infradead.org, Longbin Li <looong.bin@...il.com>
Subject: Re: [PATCH net-next v2 3/3] net: stmmac: Add glue layer for Spacemit
 K3 SoC

On Wed, Jan 21, 2026 at 02:45:24PM +0100, Andrew Lunn wrote:
> On Wed, Jan 21, 2026 at 12:05:30PM +0000, Russell King (Oracle) wrote:
> > On Wed, Jan 21, 2026 at 03:13:11PM +0800, Inochi Amaoto wrote:
> > > +	mask = RGMII_RX_DLINE_STEP | RGMII_TX_DLINE_CODE | RGMII_TX_DLINE_EN |
> > > +	       RGMII_TX_DLINE_STEP | RGMII_RX_DLINE_CODE | RGMII_RX_DLINE_EN;
> > > +	val = FIELD_PREP(RGMII_TX_DLINE_STEP, tx_config) |
> > > +	      FIELD_PREP(RGMII_TX_DLINE_CODE, tx_code) | RGMII_TX_DLINE_EN |
> > > +	      FIELD_PREP(RGMII_RX_DLINE_STEP, rx_config) |
> > > +	      FIELD_PREP(RGMII_RX_DLINE_CODE, rx_code) | RGMII_RX_DLINE_EN;
> > 
> > So your reply where you basically stated that all the RGMII.*DLINE.*
> > constants here should be the same was nonsense. How can we trust your
> > replies?
> > 
> > > +static int spacemit_dwmac_fix_delay(struct plat_stmmacenet_data *plat_dat,
> > > +				    struct regmap *apmu,
> > > +				    unsigned int dline_offset,
> > > +				    unsigned int tx_delay, unsigned int rx_delay)
> > > +{
> > > +	bool mac_rxid = rx_delay != 0;
> > > +	bool mac_txid = tx_delay != 0;
> > > +	unsigned int rx_config = 0;
> > > +	unsigned int tx_config = 0;
> > > +	int rx_code;
> > > +	int tx_code;
> > > +
> > > +	plat_dat->phy_interface = phy_fix_phy_mode_for_mac_delays(plat_dat->phy_interface,
> > > +								  mac_txid,
> > > +								  mac_rxid);
> > 
> > Maybe Andrew can confirm, but this function was to fix up existing
> > broken DT, and shouldn't be used by brand new drivers.
> 
> Hi Russell, thanks for pointing this out.
> 
> This function should not be used in this case. MAC drivers in general
> only add small delays, in order to do fine tuning. The PHY adds the
> 2ns delay. There are however some MACs who cannot disable their 2ns
> delay, or have historically been broken, and add 2ns delay. In such
> cases, the phy_interface passed to the PHY needs masking, to indicate
> the PHY should not add the 2ns delays. That is what this function
> does.
> 
> Please don't call it. Pass phy_interface as is to the PHY.
> 

Great, I will remove this call and pass the phy_interface.

Regards,
Inochi