Messages in this thread | | | Subject | Re: [PATCH v4.1] phylib: Add device reset GPIO support | From | Sergei Shtylyov <> | Date | Thu, 7 Dec 2017 20:40:37 +0300 |
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On 12/07/2017 08:20 PM, Sergei Shtylyov wrote:
>> The PHY devices sometimes do have their reset signal (maybe even power >> supply?) tied to some GPIO and sometimes it also does happen that a boot >> loader does not leave it deasserted. So far this issue has been attacked >> from (as I believe) a wrong angle: by teaching the MAC driver to manipulate >> the GPIO in question; that solution, when applied to the device trees, led >> to adding the PHY reset GPIO properties to the MAC device node, with one >> exception: Cadence MACB driver which could handle the "reset-gpios" prop >> in a PHY device subnode. I believe that the correct approach is to teach >> the 'phylib' to get the MDIO device reset GPIO from the device tree node >> corresponding to this device -- which this patch is doing... >> >> Note that I had to modify the AT803x PHY driver as it would stop working >> otherwise -- it made use of the reset GPIO for its own purposes... >> >> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> >> Acked-by: Rob Herring <robh@kernel.org> >> [geert: Propagate actual errors from fwnode_get_named_gpiod()] >> [geert: Avoid destroying initial setup] >> [geert: Consolidate GPIO descriptor acquiring code] >> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > [...] >> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c >> index 2df7b62c1a36811e..8f8b7747c54bc478 100644 >> --- a/drivers/net/phy/mdio_bus.c >> +++ b/drivers/net/phy/mdio_bus.c > [...] >> @@ -48,9 +49,26 @@ >> int mdiobus_register_device(struct mdio_device *mdiodev) >> { >> + struct gpio_desc *gpiod = NULL; >> + >> if (mdiodev->bus->mdio_map[mdiodev->addr]) >> return -EBUSY; >> + /* Deassert the optional reset signal */ > > Umm, but why deassert it here for such a short time? > >> + if (mdiodev->dev.of_node) >> + gpiod = fwnode_get_named_gpiod(&mdiodev->dev.of_node->fwnode, >> + "reset-gpios", 0, GPIOD_OUT_LOW, >> + "PHY reset"); >> + if (PTR_ERR(gpiod) == -ENOENT) >> + gpiod = NULL; >> + else if (IS_ERR(gpiod)) >> + return PTR_ERR(gpiod); > > Hm, returning on error with reset deasserted?
Oops, error means we couldn't drive the GPIO at all... The 1st question remains though...
[...]
MBR, Sergei
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