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Marek Vasut 1c45ba93d3 net: dsa: microchip: Adjust reset release timing to match reference reset circuit 
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: 5b79798090 ("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>
2021-01-20 20:52:28 -08:00
..
Kconfig net: dsa: ksz: Select KSZ protocol tag 2020-03-31 10:04:40 -07:00
ksz8795.c net: dsa: microchip: ksz8795: Fix KSZ8794 port map again 2021-01-20 20:50:49 -08:00
ksz8795_reg.h net: dsa: microchip: ksz8795: use num_vlans where possible 2020-12-02 17:16:29 -08:00
ksz8795_spi.c net: dsa: microchip: ksz8795: setup SPI mode 2020-11-25 17:53:45 -08:00
ksz9477.c net: dsa: microchip: remove usage of mib_port_count 2020-12-02 17:16:29 -08:00
ksz9477_i2c.c net: dsa: microchip: add ksz9563 to ksz9477 I2C driver 2020-10-09 13:05:56 -07:00
ksz9477_reg.h net: dsa: microchip: Use the correct style for SPDX License Identifier 2019-10-15 14:59:58 -07:00
ksz9477_spi.c net: dsa: microchip: ksz9477: setup SPI mode 2020-11-25 17:53:45 -08:00
ksz_common.c net: dsa: microchip: Adjust reset release timing to match reference reset circuit 2021-01-20 20:52:28 -08:00
ksz_common.h net: dsa: microchip: remove usage of mib_port_count 2020-12-02 17:16:29 -08:00
Makefile net: dsa: microchip: add KSZ9477 I2C driver 2019-09-12 11:36:12 +01:00