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

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Message-ID: <aXFnmXIwSdKCS9Uc@inochi.infowork>
Date: Thu, 22 Jan 2026 07:56:45 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>, 
	Inochi Amaoto <inochiama@...il.com>
Cc: 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>, Yanteng Si <siyanteng@...oftware.com.cn>, 
	Yao Zi <ziyao@...root.org>, Vladimir Oltean <vladimir.oltean@....com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>, Choong Yong Liang <yong.liang.choong@...ux.intel.com>, 
	Maxime Chevallier <maxime.chevallier@...tlin.com>, Chen-Yu Tsai <wens@...nel.org>, 
	Shangjuan Wei <weishangjuan@...incomputing.com>, Boon Khai Ng <boon.khai.ng@...era.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 3/3] net: stmmac: Add glue layer for Spacemit K3
 SoC

On Wed, Jan 21, 2026 at 12:03:36PM +0000, Russell King (Oracle) wrote:
> On Tue, Jan 20, 2026 at 01:05:39PM +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_CODE, tx_config) |
> > > > +	      FIELD_PREP(RGMII_TX_DLINE_CODE, tx_code) | RGMII_TX_DLINE_EN |
> > > > +	      FIELD_PREP(RGMII_TX_DLINE_CODE, rx_config) |
> > > > +	      FIELD_PREP(RGMII_RX_DLINE_CODE, rx_code) | RGMII_RX_DLINE_EN;
> > > 
> > > These FIELD_PREP() fields look wrong. Did you mean to use DLINE_CODE
> > > both tx_config and tx_code, and did you mean to use TX_DLINE_CODE for
> > > rx_config ?
> > > 
> > 
> > This should be RGMII_TX_DLINE_CODE. This is a copy paste error, I
> > will fix it.
> 
> Are you sure?
> 
> In that case, please change this to:
> 
> 	val = FIELD_PREP(RGMII_TX_DLINE_CODE, tx_config | tx_code |
> 					      rx_config | rx_code) |
> 	      RGMII_TX_DLINE_EN | RGMII_RX_DLINE_EN;
> 
> If that isn't what you meant, then your reply is wrong, and it seems
> you're confused, which makes me then question how reliable your
> replies are.
> 

That's wrong, I think I have reply it in a wrong way, it should be

RGMII_TX_DLINE_STEP -> tx_config
RGMII_TX_DLINE_CODE -> tx_code
RGMII_RX_DLINE_STEP -> rx_config
RGMII_RX_DLINE_CODE -> rx_code

The RGMII_[RX|TX]_DLINE_STEP register selects which step is used for
rx/tx delay. The RGMII_[RX|TX]_DLINE_CODE register provides the factor
used for calculating the delay. These register are computed in the
spacemit_dwmac_detected_delay_value(). And finally we can got a delay
with "code * step / 10 * 0.9" for both rx and tx.

> > > > +	plat_dat->clk_tx_i = devm_clk_get_enabled(&pdev->dev, "tx");
> > > > +	if (IS_ERR(plat_dat->clk_tx_i))
> > > > +		return dev_err_probe(&pdev->dev, PTR_ERR(plat_dat->clk_tx_i),
> > > > +				     "failed to get tx clock\n");
> > > 
> > > You set plat_dat->clk_tx_i, but you don't point
> > > plat_dat->set_clk_tx_rate at anything, which means the stmmac core
> > > does nothing with this.
> > > 
> > 
> > Yes, the vendor told me that the internal tx clock rate will be auto
> > changed when the speed rate is changed. So no software interaction
> > is needed.
> 
> Please do not assign a clock to clk_tx_i that is not the dwmac
> clk_tx_i input. clk_tx_i is a name used by the Synopsys DWMAC for a
> specific clock.
> 
> As you don't need to do anything with it other than to get and enable
> it, consider using just a local variable here.
> 

OK, I will use a local variable here.

Regards,
Inochi