net: phy: ksz90x1: Handle ksz9131 LED errata

Micrel KSZ9131 PHY LED behavior is not correct when configured in
Individual Mode, LED1 (Activity LED) is in the ON state when there is
no-link.

Workaround this by setting bit 9 of register 0x1e after verifying that
the LED configuration is Individual Mode.

This issue is described in KSZ9131RNX Silicon Errata DS80000693B [*]
and according to that it will not be corrected in a future silicon
revision.

[*] https://ww1.microchip.com/downloads/en/DeviceDoc/KSZ9131RNX-Silicon-Errata-and-Data-Sheet-Clarification-80000863B.pdf

Based on commit 0316c7e66bbd in the Linux kernel.

Tested-by: Quentin Schulz <quentin.schulz@cherry.de> # RK3588 Tiger
Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>

diff --git a/drivers/net/phy/micrel_ksz90x1.c b/drivers/net/phy/micrel_ksz90x1.c
index c48ae6e..ce7f2e2 100644 (file)
--- a/drivers/net/phy/micrel_ksz90x1.c
+++ b/drivers/net/phy/micrel_ksz90x1.c
@@ -389,6 +389,12 @@ U_BOOT_PHY_DRIVER(ksz9031) = {
 #define KSZ9131RN_DLL_ENABLE_DELAY     0
 #define KSZ9131RN_DLL_DISABLE_DELAY    BIT(12)
 
+#define KSZ9131RN_COMMON_CTRL                          0
+#define KSZ9131RN_COMMON_CTRL_INDIVIDUAL_LED_MODE      BIT(4)
+
+#define KSZ9131RN_LED_ERRATA_REG       0x1e
+#define KSZ9131RN_LED_ERRATA_BIT       BIT(9)
+
 static int ksz9131_config_rgmii_delay(struct phy_device *phydev)
 {
        struct phy_driver *drv = phydev->drv;
@@ -436,6 +442,28 @@ static int ksz9131_config_rgmii_delay(struct phy_device *phydev)
        return ret;
 }
 
+/* Silicon Errata DS80000693B
+ *
+ * When LEDs are configured in Individual Mode, LED1 is ON in a no-link
+ * condition. Workaround is to set register 0x1e, bit 9, this way LED1 behaves
+ * according to the datasheet (off if there is no link).
+ */
+static int ksz9131_led_errata(struct phy_device *phydev)
+{
+       int reg;
+
+       reg = phy_read_mmd(phydev, KSZ9131RN_MMD_COMMON_CTRL_REG,
+                          KSZ9131RN_COMMON_CTRL);
+       if (reg < 0)
+               return reg;
+
+       if (!(reg & KSZ9131RN_COMMON_CTRL_INDIVIDUAL_LED_MODE))
+               return 0;
+
+       return phy_set_bits(phydev, MDIO_DEVAD_NONE, KSZ9131RN_LED_ERRATA_REG,
+                           KSZ9131RN_LED_ERRATA_BIT);
+}
+
 static int ksz9131_config(struct phy_device *phydev)
 {
        int ret;
@@ -446,6 +474,10 @@ static int ksz9131_config(struct phy_device *phydev)
                        return ret;
        }
 
+       ret = ksz9131_led_errata(phydev);
+       if (ret < 0)
+               return ret;
+
        /* add an option to disable the gigabit feature of this PHY */
        if (env_get("disable_giga")) {
                unsigned features;