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From:   Pierluigi Passaro <pierluigi.p@variscite.com>
To:     Simon Horman <simon.horman@corigine.com>
CC:     "andrew@lunn.ch" <andrew@lunn.ch>,
        "hkallweit1@gmail.com" <hkallweit1@gmail.com>,
        "linux@armlinux.org.uk" <linux@armlinux.org.uk>,
        "davem@davemloft.net" <davem@davemloft.net>,
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        "kuba@kernel.org" <kuba@kernel.org>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Eran Matityahu <eran.m@variscite.com>,
        Nate Drude <Nate.D@variscite.com>,
        Francesco Ferraro <francesco.f@variscite.com>,
        "pierluigi.passaro@gmail.com" <pierluigi.passaro@gmail.com>
Subject: Re: [PATCH v2] net: mdio: force deassert MDIO reset signal
Thread-Topic: [PATCH v2] net: mdio: force deassert MDIO reset signal
Thread-Index: AQHZKSmh6qph8QozmkGz5EwYgs7b2a6g5AGAgAAfgiY=
Date:   Mon, 16 Jan 2023 13:13:49 +0000
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On Mon, Jan 16, 2023 at 12:10 PM Simon Horman <simon.horman@corigine.com> w=
rote:=0A=
> On Sun, Jan 15, 2023 at 10:37:46PM +0100, Pierluigi Passaro wrote:=0A=
> > When the reset gpio is defined within the node of the device tree=0A=
> > describing the PHY, the reset is initialized and managed only after=0A=
> > calling the fwnode_mdiobus_phy_device_register function.=0A=
> > However, before calling it, the MDIO communication is checked by the=0A=
> > get_phy_device function.=0A=
> > When this happens and the reset GPIO was somehow previously set down,=
=0A=
> > the get_phy_device function fails, preventing the PHY detection.=0A=
> > These changes force the deassert of the MDIO reset signal before=0A=
> > checking the MDIO channel.=0A=
> > The PHY may require a minimum deassert time before being responsive:=0A=
> > use a reasonable sleep time after forcing the deassert of the MDIO=0A=
> > reset signal.=0A=
> > Once done, free the gpio descriptor to allow managing it later.=0A=
> >=0A=
> > Signed-off-by: Pierluigi Passaro <pierluigi.p@variscite.com>=0A=
> > Signed-off-by: FrancescoFerraro <francesco.f@variscite.com>=0A=
> > ---=0A=
> > =A0drivers/net/mdio/fwnode_mdio.c | 25 +++++++++++++++++++++++++=0A=
> > =A01 file changed, 25 insertions(+)=0A=
> >=0A=
> > diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_m=
dio.c=0A=
> > index b782c35c4ac1..1f4b8c4c1f60 100644=0A=
> > --- a/drivers/net/mdio/fwnode_mdio.c=0A=
> > +++ b/drivers/net/mdio/fwnode_mdio.c=0A=
> > @@ -8,6 +8,8 @@=0A=
> >=0A=
> > =A0#include <linux/acpi.h>=0A=
> > =A0#include <linux/fwnode_mdio.h>=0A=
> > +#include <linux/gpio/consumer.h>=0A=
> > +#include <linux/gpio/driver.h>=0A=
> > =A0#include <linux/of.h>=0A=
> > =A0#include <linux/phy.h>=0A=
> > =A0#include <linux/pse-pd/pse.h>=0A=
> > @@ -118,6 +120,8 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus=
,=0A=
> > =A0 =A0 =A0 bool is_c45 =3D false;=0A=
> > =A0 =A0 =A0 u32 phy_id;=0A=
> > =A0 =A0 =A0 int rc;=0A=
> > + =A0 =A0 int reset_deassert_delay =3D 0;=0A=
>=0A=
> nit: it looks like scope of reset_deassert_delay could be reduced=0A=
> =A0 =A0 =A0to the else clause where it is used.=0A=
>=0A=
no problem.=0A=
>=0A=
> > + =A0 =A0 struct gpio_desc *reset_gpio;=0A=
>=0A=
> nit: reverse xmas tree for local variable declarations=0A=
>=0A=
I'm worried I'm asking something stupid: what do you mean by=0A=
"reverse xmas tree" ?> ...=0A=
>=0A=
> Also, if reposting, the target tree for this should be in the subject.=0A=
> Assuming net-next, that would mean "[PATCH net-next v3]"=0A=
>=0A=
no problem=