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

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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 <geert+renesas@glider.be>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/9002a58daa1b2983f39815b748ee9d2f8dcc4829.1730366936.git.geert+renesas@glider.be
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Nobuhiro Iwamatsu (CIP) <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven
2024-10-31 10:29:51 +01:00
committed by Greg Kroah-Hartman
parent 94ec33e960
commit eb74c6f1b2
1 changed files with 1 additions and 1 deletions
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2
arch/arm/boot/dts/ti/omap/am335x-bone-common.dtsi
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@@ -385,7 +385,7 @@
/* 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>;
};
};