linux-kernel - Re: [PATCH net] net: phy: micrel: Make the GPIO to be non-exclusive

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Date:   Thu, 25 Aug 2022 08:54:11 +0200
From:   Horatiu Vultur <horatiu.vultur@...rochip.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <hkallweit1@...il.com>, <linux@...linux.org.uk>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <michael@...le.cc>,
        <UNGLinuxDriver@...rochip.com>, <maxime.chevallier@...tlin.com>
Subject: Re: [PATCH net] net: phy: micrel: Make the GPIO to be non-exclusive

The 08/24/2022 21:47, Andrew Lunn wrote:

Hi Andrew,

> 
> On Wed, Aug 24, 2022 at 09:28:27PM +0200, Horatiu Vultur wrote:
> > The same GPIO line can be shared by multiple phys for the coma mode pin.
> > If that is the case then, all the other phys that share the same line
> > will failed to be probed because the access to the gpio line is not
> > non-exclusive.
> > Fix this by making access to the gpio line to be nonexclusive using flag
> > GPIOD_FLAGS_BIT_NONEXCLUSIVE. This allows all the other PHYs to be
> > probed.
> >
> > Fixes: 738871b09250ee ("net: phy: micrel: add coma mode GPIO")
> > Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
> > ---
> >  drivers/net/phy/micrel.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> > index e78d0bf69bc3..ea72ff64ad33 100644
> > --- a/drivers/net/phy/micrel.c
> > +++ b/drivers/net/phy/micrel.c
> > @@ -2878,7 +2878,8 @@ static int lan8814_release_coma_mode(struct phy_device *phydev)
> >       struct gpio_desc *gpiod;
> >
> >       gpiod = devm_gpiod_get_optional(&phydev->mdio.dev, "coma-mode",
> > -                                     GPIOD_OUT_HIGH_OPEN_DRAIN);
> > +                                     GPIOD_OUT_HIGH_OPEN_DRAIN |
> > +                                     GPIOD_FLAGS_BIT_NONEXCLUSIVE);
> 
> I would suggest putting a comment here. You are assuming the driver
> never gains a lan8814_take_coma_mode() when the PHY is put into
> suspend, since it sounds like that will put all PHYs on the shared
> GPIO into coma mode.

That is correct.
I will add a comment in the next version.

> 
>      Andrew

-- 
/Horatiu