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

[Inochi Amaoto <inochiama@gmail.com>]

On Tue, Jan 20, 2026 at 11:13:50AM +0000, Yao Zi wrote:
> On Tue, Jan 20, 2026 at 12:36:08PM +0800, Inochi Amaoto wrote:
> > Adds Spacemit dwmac driver support on the Spacemit K3 SoC.
> > 
> > Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
> > ---
> >  drivers/net/ethernet/stmicro/stmmac/Kconfig   |  12 +
> >  drivers/net/ethernet/stmicro/stmmac/Makefile  |   1 +
> >  .../ethernet/stmicro/stmmac/dwmac-spacemit.c  | 224 ++++++++++++++++++
> >  3 files changed, 237 insertions(+)
> >  create mode 100644 drivers/net/ethernet/stmicro/stmmac/dwmac-spacemit.c
> 
> ...
> 
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-spacemit.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-spacemit.c
> > new file mode 100644
> > index 000000000000..72744e60d02a
> > --- /dev/null
> > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-spacemit.c
> > @@ -0,0 +1,224 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Spacemit DWMAC platform driver
> > + *
> > + * Copyright (C) 2026 Inochi Amaoto <inochiama@gmail.com>
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/math.h>
> 
> These are the only two headers listed out-of-order. Is this intended?
> 

I will fix this.

> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/property.h>
> > +#include <linux/regmap.h>
> 
> ...
> 
> > +static int spacemit_dwmac_detected_delay_value(unsigned int delay,
> > +					       unsigned int *config)
> > +{
> > +	int i;
> > +	int code, best_code = 0;
> > +	unsigned int best_delay = 0;
> > +	unsigned int best_config = 0;
> > +
> > +	if (delay == 0)
> > +		return 0;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(k3_delay_step_10x); i++) {
> > +		unsigned int step = k3_delay_step_10x[i];
> > +
> > +		for (code = 1; code <= MAX_DLINE_DELAY_CODE; code++) {
> > +			/*
> > +			 * Note K3 require a specific factor for calculate
> > +			 * the delay, in this scenario it is 0.9. So the
> > +			 * formula is code * step / 10 * 0.9
> > +			 */
> > +			unsigned int tmp = code * step * 9 / 10 / 10;
> > +
> > +			if (abs(tmp - delay) < abs(best_delay - delay)) {
> > +				best_code = code;
> > +				best_delay = tmp;
> > +				best_config = i;
> > +			}
> 
> Is the inner loop really necessary? Could it be replaced by
> 
> 	this_code = DIV_ROUND_CLOSEST(delay * 10 * 10, step * 9);
> 	this_delay = this_code * step * 9 / 10 / 10;
> 
> Then comparing abs(this_delay - delay) and abs(best_delay - delay)?
> 

This is a good idea, thanks.

> > +		}
> > +	}
> > +
> > +	*config = best_config;
> > +
> > +	return best_code;
> > +}
> 
> ...
> 
> > +static int spacemit_dwmac_update_ifconfig(struct plat_stmmacenet_data *plat_dat,
> > +					  struct stmmac_resources *stmmac_res,
> > +					  struct regmap *apmu,
> > +					  unsigned int ctrl_offset)
> > +{
> > +	unsigned int mask = PHY_INTF_MII | PHY_INTF_RGMII | WAKE_IRQ_EN;
> > +	unsigned int val = 0;
> > +
> > +	switch (plat_dat->phy_interface) {
> > +	case PHY_INTERFACE_MODE_MII:
> > +		val |= PHY_INTF_MII;
> > +		break;
> 
> The OR operation seems unnecessary and could be replaced with an
> assignment. Same for PHY_INTERFACE_MODE_RGMII's case.
> 

That's tree, an assignment is better than the OR operation, I will
change this in the next version.

> > +
> > +	case PHY_INTERFACE_MODE_RMII:
> > +		break;
> > +
> > +	case PHY_INTERFACE_MODE_RGMII:
> > +	case PHY_INTERFACE_MODE_RGMII_ID:
> > +	case PHY_INTERFACE_MODE_RGMII_RXID:
> > +	case PHY_INTERFACE_MODE_RGMII_TXID:
> > +		val |= PHY_INTF_RGMII;
> > +		break;
> > +
> > +	default:
> > +		return -EOPNOTSUPP;
> > +	}
> 
> ...
> 
> > +static int spacemit_dwmac_probe(struct platform_device *pdev)
> > +{
> 
> ...
> 
> > +	of_property_read_u32(pdev->dev.of_node, "tx-internal-delay-ps", &tx_delay);
> > +	of_property_read_u32(pdev->dev.of_node, "rx-internal-delay-ps", &rx_delay);
> 
> According to of.h, of_property_read_u32, which in turn calls
> of_property_read_u32_array, could fail with -ENODATA if there's no value
> associated with the property. Should the case be handled?
> 
> Regards,
> Yao Zi