@@ -1528,6 +1528,78 @@ void ksz8_config_cpu_port(struct dsa_switch *ds)
}
}
+/**
+ * ksz8_phy_port_link_up - Configures ports with integrated PHYs
+ * @dev: The KSZ device instance.
+ * @port: The port number to configure.
+ * @duplex: The desired duplex mode.
+ * @tx_pause: If true, enables transmit pause.
+ * @rx_pause: If true, enables receive pause.
+ *
+ * Description:
+ * The function configures flow control settings for a given port based on the
+ * desired settings and current duplex mode.
+ *
+ * According to the KSZ8873 datasheet, the PORT_FORCE_FLOW_CTRL bit in the
+ * Port Control 2 register (0x1A for Port 1, 0x22 for Port 2, 0x32 for Port 3)
+ * determines how flow control is handled on the port:
+ * "1 = will always enable full-duplex flow control on the port, regardless
+ * of AN result.
+ * 0 = full-duplex flow control is enabled based on AN result."
+ *
+ * This means that the flow control behavior depends on the state of this bit:
+ * - If PORT_FORCE_FLOW_CTRL is set to 1, the switch will ignore AN results and
+ * force flow control on the port.
+ * - If PORT_FORCE_FLOW_CTRL is set to 0, the switch will enable or disable
+ * flow control based on the AN results.
+ *
+ * However, there is a potential limitation in this configuration. It is
+ * currently not possible to force disable flow control on a port if we still
+ * advertise pause support. While such a configuration is not currently
+ * supported by Linux, and may not make practical sense, it's important to be
+ * aware of this limitation when working with the KSZ8873 and similar devices.
+ */
+static void ksz8_phy_port_link_up(struct ksz_device *dev, int port, int duplex,
+ bool tx_pause, bool rx_pause)
+{
+ const u16 *regs = dev->info->regs;
+ bool aneg_en;
+ u8 sctrl = 0;
+ u8 fctrl;
+ int ret;
+
+ /* The KSZ8795 switch differs from the KSZ8873 by supporting
+ * asymmetric pause control. However, since a single bit is used to
+ * control both RX and TX pause, we can't enforce asymmetric pause
+ * control - both TX and RX pause will be either enabled or disabled
+ * together.
+ *
+ * If auto-negotiation is enabled, we usually allow the flow control to
+ * be determined by the auto-negotiation process based on the
+ * capabilities of both link partners. However, for KSZ8873, the
+ * PORT_FORCE_FLOW_CTRL bit may be set by the hardware bootstrap,
+ * ignoring the auto-negotiation result. Thus, even in auto-negotiation
+ * mode, we need to ensure that the PORT_FORCE_FLOW_CTRL bit is
+ * properly cleared.
+ *
+ * In the absence of auto-negotiation, we will enforce symmetric
+ * pause control for both variants of switches - KSZ8873 and KSZ8795.
+ */
+ ret = ksz_pread8(dev, port, regs[P_FORCE_CTRL], &fctrl);
+ if (ret)
+ return;
+
+ if (ksz_is_ksz88x3(dev))
+ aneg_en = fctrl & PORT_AUTO_NEG_ENABLE;
+ else
+ aneg_en = !(fctrl & PORT_AUTO_NEG_DISABLE);
+
+ if (!aneg_en && (tx_pause || rx_pause))
+ sctrl |= PORT_FORCE_FLOW_CTRL;
+
+ ksz_prmw8(dev, port, regs[P_STP_CTRL], PORT_FORCE_FLOW_CTRL, sctrl);
+}
+
/**
* ksz8_cpu_port_link_up - Configures the CPU port of the switch.
* @dev: The KSZ device instance.
@@ -1577,6 +1649,8 @@ void ksz8_phylink_mac_link_up(struct ksz_device *dev, int port,
*/
if (dev->cpu_port == port)
ksz8_cpu_port_link_up(dev, speed, duplex, tx_pause, rx_pause);
+ else if (dev->info->internal_phy[port])
+ ksz8_phy_port_link_up(dev, port, duplex, tx_pause, rx_pause);
}
static int ksz8_handle_global_errata(struct dsa_switch *ds)