Re: [RFC 13/13] net: ti: icssg-prueth: Add ICSSG ethernet driver

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 12/04/2022 12:45, Puranjay Mohan wrote:
+ Roger, Grygorii

On 07/04/22 00:07, Andrew Lunn wrote:
+static int emac_phy_connect(struct prueth_emac *emac)
+{
+	struct prueth *prueth = emac->prueth;
+
+	/* connect PHY */
+	emac->phydev = of_phy_connect(emac->ndev, emac->phy_node,
+				      &emac_adjust_link, 0, emac->phy_if);

+static int prueth_config_rgmiidelay(struct prueth *prueth,
+				    struct device_node *eth_np,
+				    phy_interface_t phy_if)
+{
+	struct device *dev = prueth->dev;
+	struct regmap *ctrl_mmr;
+	u32 rgmii_tx_id = 0;
+	u32 icssgctrl_reg;
+
+	if (!phy_interface_mode_is_rgmii(phy_if))
+		return 0;
+
+	ctrl_mmr = syscon_regmap_lookup_by_phandle(eth_np, "ti,syscon-rgmii-delay");
+	if (IS_ERR(ctrl_mmr)) {
+		dev_err(dev, "couldn't get ti,syscon-rgmii-delay\n");
+		return -ENODEV;
+	}
+
+	if (of_property_read_u32_index(eth_np, "ti,syscon-rgmii-delay", 1,
+				       &icssgctrl_reg)) {
+		dev_err(dev, "couldn't get ti,rgmii-delay reg. offset\n");
+		return -ENODEV;
+	}
+
+	if (phy_if == PHY_INTERFACE_MODE_RGMII_ID ||
+	    phy_if == PHY_INTERFACE_MODE_RGMII_TXID)
+		rgmii_tx_id |= ICSSG_CTRL_RGMII_ID_MODE;
+
+	regmap_update_bits(ctrl_mmr, icssgctrl_reg, ICSSG_CTRL_RGMII_ID_MODE, rgmii_tx_id);
+
+	return 0;
+}


O.K, so this does not do what i initially thought it was doing. I was
thinking it was to fine tune the delay, ti,syscon-rgmii-delay would be
a small pico second value to allow the 2ns delay to be tuned to the
board.

But now i think this is actually inserting the full 2ns delay?

The problem is, you also pass phy_if to of_phy_connect() so the PHY
will also insert the delay if requested. So you end up with double
delays for rgmii_id and rgmii_txid.

It's misunderstanding here. The bit field name in TRM is RGMII0_ID_MODE
and meaning:
0h - Internal transmit delay is enabled
1h - Internal transmit delay is not enabled.

So here internal delay will be disabled for RGMII_ID/RGMII_TXID.


The general recommendation is that the PHY inserts the delay, based on
phy-mode. The MAC does not add a delay, so i suggest you always write
0 here, just to ensure the system is in a deterministic state, and the
bootloader and not being messing around with things.

	   Andrew

--
Best regards,
Grygorii, Ukraine



[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux