KSZ8794CNX datasheet section 8.0 RESET CIRCUIT describes recommended
circuit for interfacing with CPU/FPGA reset consisting of 10k pullup
resistor and 10uF capacitor to ground. This circuit takes ~100 mS to
rise enough to release the reset.
For maximum supply voltage VDDIO=3.3V VIH=2.0V R=10kR C=10uF that is
VDDIO - VIH
t = R * C * -ln( ------------- ) = 10000*0.00001*-(-0.93)=0.093 S
VDDIO
so we need ~95 mS for the reset to really de-assert, and then the
original 100uS for the switch itself to come out of reset. Simply
msleep() for 100 mS which fits the constraint with a bit of extra
space.
Fixes: 5b797980908a ("net: dsa: microchip: Implement recommended reset timing")
Signed-off-by: Marek Vasut <ma...@denx.de>
Cc: Andrew Lunn <and...@lunn.ch>
Cc: Florian Fainelli <f.faine...@gmail.com>
Cc: Jakub Kicinski <k...@kernel.org>
Cc: Michael Grzeschik <m.grzesc...@pengutronix.de>
Cc: Paul Barker <pbar...@konsulko.com>
---
drivers/net/dsa/microchip/ksz_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/dsa/microchip/ksz_common.c
b/drivers/net/dsa/microchip/ksz_common.c
index 489963664443..389abfd27770 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -400,7 +400,7 @@ int ksz_switch_register(struct ksz_device *dev,
gpiod_set_value_cansleep(dev->reset_gpio, 1);
usleep_range(10000, 12000);
gpiod_set_value_cansleep(dev->reset_gpio, 0);
- usleep_range(100, 1000);
+ msleep(100);
}
mutex_init(&dev->dev_mutex);
--
2.29.2
