netdev - Re: [RFC PATCH 2/2] net: stmmac: dwmac-sun8i: Allow runtime AC200/AC300 phy selection

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Message-ID: <7a42e9d1-93ce-4666-b7e7-3c0b4e2c0c99@linux.dev>
Date: Mon, 26 May 2025 09:38:41 +0800
From: Yanteng Si <si.yanteng@...ux.dev>
To: James Hilliard <james.hilliard1@...il.com>, netdev@...r.kernel.org
Cc: linux-sunxi@...ts.linux.dev, 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>,
 Chen-Yu Tsai <wens@...e.org>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Samuel Holland <samuel@...lland.org>,
 Maxime Coquelin <mcoquelin.stm32@...il.com>,
 Alexandre Torgue <alexandre.torgue@...s.st.com>,
 Yinggang Gu <guyinggang@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>,
 Feiyang Chen <chenfeiyang@...ngson.cn>,
 Uwe Kleine-König <u.kleine-koenig@...libre.com>,
 "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
 Jinjie Ruan <ruanjinjie@...wei.com>, Paul Kocialkowski <paulk@...-base.io>,
 linux-arm-kernel@...ts.infradead.org,
 linux-stm32@...md-mailman.stormreply.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/2] net: stmmac: dwmac-sun8i: Allow runtime
 AC200/AC300 phy selection

在 5/26/25 8:29 AM, James Hilliard 写道:
> The Allwinner H616 ships with two different on-die phy variants, in
> order to determine the phy being used we need to read an efuse and
> then select the appropriate PHY based on the AC300 bit.
>
> By defining an emac node without a phy-handle we can override the
> default PHY selection logic in stmmac by passing a specific phy_node
> selected based on the ac200 and ac300 names in a phys list.
>
> This allows us to have a device tree that defines both PHY variants
> even though only one will actually end up being used at runtime
> based on the ac300 nvmem efuse bit.
>
> Signed-off-by: James Hilliard <james.hilliard1@...il.com>
> ---
>   .../net/ethernet/stmicro/stmmac/dwmac-sun8i.c | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
> index 6c7e8655a7eb..e275f4caa684 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
> @@ -11,6 +11,7 @@
>   #include <linux/mdio-mux.h>
>   #include <linux/mfd/syscon.h>
>   #include <linux/module.h>
> +#include <linux/nvmem-consumer.h>
>   #include <linux/of.h>
>   #include <linux/of_mdio.h>
>   #include <linux/of_net.h>
> @@ -280,6 +281,8 @@ static const struct emac_variant emac_variant_h6 = {
>   #define SYSCON_ETCS_EXT_GMII	0x1
>   #define SYSCON_ETCS_INT_GMII	0x2
>   

> +#define AC300_KEY		BIT(8)
> +

I have observed all the BIT macros in this file, and they all

have a line of comments. I think a comment is also needed here.

>   /* sun8i_dwmac_dma_reset() - reset the EMAC
>    * Called from stmmac via stmmac_dma_ops->reset
>    */
> @@ -1159,6 +1162,7 @@ static int sun8i_dwmac_probe(struct platform_device *pdev)
>   	struct net_device *ndev;
>   	struct regmap *regmap;
>   	int ret;
> +	u16 val;
>   
>   	ret = stmmac_get_platform_resources(pdev, &stmmac_res);
>   	if (ret)
> @@ -1222,6 +1226,21 @@ static int sun8i_dwmac_probe(struct platform_device *pdev)
>   	if (IS_ERR(plat_dat))
>   		return PTR_ERR(plat_dat);
>   
> +	if (!nvmem_cell_read_u16(dev, "ac300", &val)) {
> +		const char *phy_name = (val & AC300_KEY) ? "ac300" : "ac200";
> +		int index = of_property_match_string(dev->of_node, "phy-names", phy_name);
> +		if (index < 0) {
> +			dev_err(dev, "PHY name not found in device tree\n");
> +			return -EINVAL;
> +		}
> +
> +		plat_dat->phy_node = of_parse_phandle(dev->of_node, "phys", index);
> +		if (!plat_dat->phy_node) {
> +			dev_err(dev, "Failed to get PHY node from phys property\n");
> +			return -EINVAL;
> +		}
> +	}
> +
How about preparing a separate function for it?  Then call it in probe().

If you are willing to do so, remember to write a code comment.

Thanks,

Yanteng