ARM: dts: am335x-bone-common: Increase MDIO reset deassert delay to 50ms

commit 929d8490f8790164f5f63671c1c58d6c50411cb2 upstream.

Commit b9bf5612610aa7e3 ("ARM: dts: am335x-bone-common: Increase MDIO
reset deassert time") already increased the MDIO reset deassert delay
from 6.5 to 13 ms, but this may still cause Ethernet PHY probe failures:

    SMSC LAN8710/LAN8720 4a101000.mdio:00: probe with driver SMSC LAN8710/LAN8720 failed with error -5

On BeagleBone Black Rev. C3, ETH_RESETn is controlled by an open-drain
AND gate.  It is pulled high by a 10K resistor, and has a 4.7µF
capacitor to ground, giving an RC time constant of 47ms.  As it takes
0.7RC to charge the capacitor above the threshold voltage of a CMOS
input (VDD/2), the delay should be at least 33ms.  Considering the
typical tolerance of 20% on capacitors, 40ms would be safer.  Add an
additional safety margin and settle for 50ms.

Signed-off-by: Geert Uytterhoeven <[email protected]>
Reviewed-by: Roger Quadros <[email protected]>
Link: https://lore.kernel.org/r/9002a58daa1b2983f39815b748ee9d2f8dcc4829.1730366936.git.geert+renesas@glider.be
Signed-off-by: Kevin Hilman <[email protected]>
Signed-off-by: Nobuhiro Iwamatsu (CIP) <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: geertu

arch/arm/boot/dts/am335x-bone-common.dtsi

@@ -384,7 +384,7 @@
 		/* Support GPIO reset on revision C3 boards */
 		reset-gpios = <&gpio1 8 GPIO_ACTIVE_LOW>;
 		reset-assert-us = <300>;
-		reset-deassert-us = <13000>;
+		reset-deassert-us = <50000>;
 	};
 };