Subject: Re: [PATCH RFC net-next] net: ethernet: mtk_eth_soc: add paths and SerDes modes for MT7988

From: "Russell King (Oracle)" <[email-masked]>
Date: Tue, 22 Aug 2023 19:33:12 +0100

Hi,

I haven't fully reviewed this yet, but here's some initial comments.

On Tue, Aug 22, 2023 at 07:04:42PM +0100, Daniel Golle wrote:
> MT7988 comes with a built-in 2.5G PHY as well as SerDes lanes to
> connect external PHYs or transceivers in USXGMII, 10GBase-R, 5GBase-KR,

5Gbase-KR K normally means backplane mode.

> +/* Register to read PCS AN status */
> +#define RG_PCS_AN_STS0		0x81c
> +#define USXGMII_LPA_SPEED_MASK	GENMASK(11, 9)
> +#define USXGMII_LPA_SPEED_10	0
> +#define USXGMII_LPA_SPEED_100	1
> +#define USXGMII_LPA_SPEED_1000	2
> +#define USXGMII_LPA_SPEED_10000	3
> +#define USXGMII_LPA_SPEED_2500	4
> +#define USXGMII_LPA_SPEED_5000	5
> +#define USXGMII_LPA_DUPLEX	BIT(12)
> +#define USXGMII_LPA_LINK	BIT(15)

Aren't these the same as the MDIO_USXGMII_xxx definitions that define
the UsxgmiiChannelInfo[15:0] bits?

> +static int mtk_usxgmii_pcs_config(struct phylink_pcs *pcs, unsigned int neg_mode,
> +				  phy_interface_t interface,
> +				  const unsigned long *advertising,
> +				  bool permit_pause_to_mac)
> +{
> +	struct mtk_usxgmii_pcs *mpcs = pcs_to_mtk_usxgmii_pcs(pcs);
> +	struct mtk_eth *eth = mpcs->eth;
> +	struct regmap *pextp = eth->regmap_pextp[mpcs->id];
> +	unsigned int an_ctrl = 0, link_timer = 0, xfi_mode = 0, adapt_mode = 0;
> +	bool mode_changed = false;
> +
> +	if (!pextp)
> +		return -ENODEV;
> +
> +	if (interface == PHY_INTERFACE_MODE_USXGMII) {
> +		an_ctrl = FIELD_PREP(USXGMII_AN_SYNC_CNT, 0x1FF) |
> +			  (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED) ?

Using the new neg_mode here... but you haven't set pcs.neg_mode below
true.

> +static void mtk_usxgmii_pcs_get_state(struct phylink_pcs *pcs,
> +				      struct phylink_link_state *state)
> +{
> +	struct mtk_usxgmii_pcs *mpcs = pcs_to_mtk_usxgmii_pcs(pcs);
> +	struct mtk_eth *eth = mpcs->eth;
> +	struct mtk_mac *mac = eth->mac[mtk_xgmii2mac_id(eth, mpcs->id)];
> +	u32 val = 0;
> +
> +	regmap_read(mpcs->regmap, RG_PCS_AN_CTRL0, &val);
> +	if (FIELD_GET(USXGMII_AN_ENABLE, val)) {
> +		/* Refresh LPA by inverting LPA_LATCH */
> +		regmap_read(mpcs->regmap, RG_PCS_AN_STS0, &val);
> +		regmap_update_bits(mpcs->regmap, RG_PCS_AN_STS0,
> +				   USXGMII_LPA_LATCH,
> +				   !(val & USXGMII_LPA_LATCH));
> +
> +		regmap_read(mpcs->regmap, RG_PCS_AN_STS0, &val);
> +
> +		state->interface = mpcs->interface;
> +		state->link = FIELD_GET(USXGMII_LPA_LINK, val);
> +		state->duplex = FIELD_GET(USXGMII_LPA_DUPLEX, val);
> +
> +		switch (FIELD_GET(USXGMII_LPA_SPEED_MASK, val)) {
> +		case USXGMII_LPA_SPEED_10:
> +			state->speed = SPEED_10;
> +			break;
> +		case USXGMII_LPA_SPEED_100:
> +			state->speed = SPEED_100;
> +			break;
> +		case USXGMII_LPA_SPEED_1000:
> +			state->speed = SPEED_1000;
> +			break;
> +		case USXGMII_LPA_SPEED_2500:
> +			state->speed = SPEED_2500;
> +			break;
> +		case USXGMII_LPA_SPEED_5000:
> +			state->speed = SPEED_5000;
> +			break;
> +		case USXGMII_LPA_SPEED_10000:
> +			state->speed = SPEED_10000;
> +			break;
> +		}

Maybe consider using phylink_decode_usxgmii_word() ?

> +	} else {
> +		val = mtk_r32(mac->hw, MTK_XGMAC_STS(mac->id));
> +
> +		if (mac->id == MTK_GMAC2_ID)
> +			val >>= 16;
> +
> +		switch (FIELD_GET(MTK_USXGMII_PCS_MODE, val)) {
> +		case 0:
> +			state->speed = SPEED_10000;
> +			break;
> +		case 1:
> +			state->speed = SPEED_5000;
> +			break;
> +		case 2:
> +			state->speed = SPEED_2500;
> +			break;
> +		case 3:
> +			state->speed = SPEED_1000;
> +			break;
> +		}
> +
> +		state->interface = mpcs->interface;
> +		state->link = FIELD_GET(MTK_USXGMII_PCS_LINK, val);
> +		state->duplex = DUPLEX_FULL;
> +	}
> +
> +	if (state->link == 0)
> +		mtk_usxgmii_pcs_config(pcs, MLO_AN_INBAND,

Passing old-style mode rather than neg_mode here.

> +				       state->interface, NULL, false);

It would be good to describe why you're reconfiguring the interface
here. You describe why in mtk_usxgmii_pcs_link_up...

> +		eth->usxgmii_pcs[i] = devm_kzalloc(dev, sizeof(*eth->usxgmii_pcs), GFP_KERNEL);
> +		if (!eth->usxgmii_pcs[i])
> +			return -ENOMEM;
> +
> +		eth->usxgmii_pcs[i]->id = i;
> +		eth->usxgmii_pcs[i]->eth = eth;
> +		eth->usxgmii_pcs[i]->regmap = syscon_node_to_regmap(np);
> +		if (IS_ERR(eth->usxgmii_pcs[i]->regmap))
> +			return PTR_ERR(eth->usxgmii_pcs[i]->regmap);
> +
> +		eth->usxgmii_pcs[i]->pcs.ops = &mtk_usxgmii_pcs_ops;
> +		eth->usxgmii_pcs[i]->pcs.poll = true;
> +		eth->usxgmii_pcs[i]->interface = PHY_INTERFACE_MODE_NA;

All new PCS should set pcs.neg_mode true.

Thanks.

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