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Subject[PATCH] net: mdiobus: Prevent spike on MDIO bus reset signal
Date
The mdio_bus reset code first de-asserted the reset by allocating with
GPIOD_OUT_LOW, then asserted and de-asserted again. In other words, if
the reset signal defaulted to asserted, there'd be a short "spike"
before the reset.

Instead, directly assert the reset signal using GPIOD_OUT_HIGH, this
removes the spike and also removes a line of code since the signal
is already high.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>

---

drivers/net/phy/mdio_bus.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 2b42e46066b4..34e98ae75110 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -543,8 +543,8 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
mutex_init(&bus->mdio_lock);
mutex_init(&bus->shared_lock);

- /* de-assert bus level PHY GPIO reset */
- gpiod = devm_gpiod_get_optional(&bus->dev, "reset", GPIOD_OUT_LOW);
+ /* assert bus level PHY GPIO reset */
+ gpiod = devm_gpiod_get_optional(&bus->dev, "reset", GPIOD_OUT_HIGH);
if (IS_ERR(gpiod)) {
err = dev_err_probe(&bus->dev, PTR_ERR(gpiod),
"mii_bus %s couldn't get reset GPIO\n",
@@ -553,8 +553,6 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
return err;
} else if (gpiod) {
bus->reset_gpiod = gpiod;
-
- gpiod_set_value_cansleep(gpiod, 1);
fsleep(bus->reset_delay_us);
gpiod_set_value_cansleep(gpiod, 0);
if (bus->reset_post_delay_us > 0)
--
2.17.1
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