netdev - Re: [net-next,20/21] net: stmmac: rk: use rk_encode

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Message-ID: <20260125221634.3396295-1-kuba@kernel.org>
Date: Sun, 25 Jan 2026 14:16:34 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: rmk+kernel@...linux.org.uk
Cc: Jakub Kicinski <kuba@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	andrew@...n.ch,
	davem@...emloft.net,
	alexandre.torgue@...s.st.com,
	netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	heiko@...ech.de,
	andrew+netdev@...n.ch,
	linux-rockchip@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com
Subject: Re: [net-next,20/21] net: stmmac: rk: use rk_encode_wm16() for clock selection

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
net: stmmac: rk: rk3506, rk3528 and kk3588 have rmii_mode in clock register

This patch adds an rmii_mode_mask field to struct rk_clock_fields to handle
RMII mode configuration in the clock GRF register. It removes the SoC-specific
set_to_rmii() functions for rk3506, rk3528, and rk3588, replacing them with a
generic mechanism in rk_gmac_powerup().

> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> index ebbc09ea572a..759deb66ef2a 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c

[ ... ]

> @@ -1412,6 +1385,15 @@ static int rk_gmac_powerup(struct rk_priv_data *bsp_priv)
>  			return ret;
>  	}
>
> +	if (bsp_priv->clock.rmii_mode_mask) {
> +		val = rk_encode_wm16(ret == PHY_INTF_SEL_RMII,
> +				     bsp_priv->clock.rmii_mode_mask);

Is this comparison using the correct value? Earlier in rk_gmac_powerup(), the
variable ret is assigned the return value from rk_get_phy_intf_sel(), which is
PHY_INTF_SEL_RGMII (0) or PHY_INTF_SEL_RMII (1).

However, for SoCs that have gmac_phy_intf_sel_mask set (such as rk3588), the
code enters the preceding if block:

    if (bsp_priv->gmac_phy_intf_sel_mask || bsp_priv->gmac_rmii_mode_mask) {
        ...
        ret = regmap_write(bsp_priv->grf, bsp_priv->gmac_grf_reg, val);
        ...
    }

After this block, ret has been overwritten with the regmap_write() return
value (0 on success). When the rmii_mode_mask block executes, the comparison
ret == PHY_INTF_SEL_RMII becomes 0 == 1, which is always false.

This means for rk3588 in RMII mode, the rmii_mode bit in the clock register
will be cleared (RGMII mode) instead of set. Would it be better to save the
PHY interface selection value in a separate variable before it gets
overwritten?

> +
> +		ret = rk_write_clock_grf_reg(bsp_priv, val);
> +		if (ret < 0)
> +			return ret;
> +	}