From: Wenyou Yang <wenyou.y...@atmel.com>

[ Upstream commit b8659752c37ec157ee254cff443b1c9d523aea22 ]

Appearance: On some SAMA5D4EK boards, after power up, the Eth1 doesn't work.

Reason: The PIOE2 pin is connected to the NAND_Tree# of KSZ8081,
But it outputs LOW during the reset period, which cause the NAND_Tree# enabled.

Add phy_fixup() to disable NAND_Tree by overriding the Operation
Mode Strap Override register(i.e. Register 16h) to clear the NAND_Tree bit.

Signed-off-by: Wenyou Yang <wenyou.y...@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.fe...@atmel.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 arch/arm/mach-at91/board-dt-sama5.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/arm/mach-at91/board-dt-sama5.c 
b/arch/arm/mach-at91/board-dt-sama5.c
index 129e2917506b..5e4cedfa5c51 100644
--- a/arch/arm/mach-at91/board-dt-sama5.c
+++ b/arch/arm/mach-at91/board-dt-sama5.c
@@ -17,6 +17,7 @@
 #include <linux/of_platform.h>
 #include <linux/phy.h>
 #include <linux/clk-provider.h>
+#include <linux/phy.h>
 
 #include <asm/setup.h>
 #include <asm/irq.h>
@@ -27,8 +28,25 @@
 #include "at91_aic.h"
 #include "generic.h"
 
+static int ksz8081_phy_fixup(struct phy_device *phy)
+{
+       int value;
+
+       value = phy_read(phy, 0x16);
+       value &= ~0x20;
+       phy_write(phy, 0x16, value);
+
+       return 0;
+}
+
 static void __init sama5_dt_device_init(void)
 {
+       if (of_machine_is_compatible("atmel,sama5d4ek") &&
+          IS_ENABLED(CONFIG_PHYLIB)) {
+               phy_register_fixup_for_id("fc028000.etherne:00",
+                                               ksz8081_phy_fixup);
+       }
+
        of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
 }
 
-- 
2.17.1

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