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Subject[PATCH net-next v2] net: phy: micrel: ksz9131 led errata workaround
Date
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

Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
---
Changes v1 => v2:
1. corrected errata URL in commit message
2. check phy_read_mmd return value
---
drivers/net/phy/micrel.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index c330a5a9f665..b70f62efdbc3 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1003,6 +1003,26 @@ static int ksz9131_config_rgmii_delay(struct phy_device *phydev)
txcdll_val);
}

+/* 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, 2, 0);
+ if (reg < 0)
+ return reg;
+
+ if (!(reg & BIT(4)))
+ return 0;
+
+ return phy_set_bits(phydev, 0x1e, BIT(9));
+}
+
static int ksz9131_config_init(struct phy_device *phydev)
{
struct device_node *of_node;
@@ -1058,6 +1078,10 @@ static int ksz9131_config_init(struct phy_device *phydev)
if (ret < 0)
return ret;

+ ret = ksz9131_led_errata(phydev);
+ if (ret < 0)
+ return ret;
+
return 0;
}

--
2.25.1
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