diff options
| author | Marek Vasut <marex@denx.de> | 2021-01-20 06:05:02 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-07 17:37:11 +0300 |
| commit | 1aa4ee0ec7fe929bd46ae20d9457f0a242115643 (patch) | |
| tree | a882474f9bfbe997297c0fca04bc8ae24dfcf741 | |
| parent | 0c245c5fe93f0e9769de4a8b31f129b2759bf802 (diff) | |
| download | linux-1aa4ee0ec7fe929bd46ae20d9457f0a242115643.tar.xz | |
net: dsa: microchip: Adjust reset release timing to match reference reset circuit
commit 1c45ba93d34cd6af75228f34d0675200c81738b5 upstream.
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")
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>
Reviewed-by: Paul Barker <pbarker@konsulko.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20210120030502.617185-1-marex@denx.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/net/dsa/microchip/ksz_common.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c index 0ef854911f21..d4a64dbde315 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); |