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    SubjectRe: [PATCH] dp83640: Ensure against premature access to PHY registers after reset
    On Fri, Apr 06, 2018 at 04:05:40PM +0200, Esben Haabendal wrote:
    > From: Esben Haabendal <eha@deif.com>
    >
    > Signed-off-by: Esben Haabendal <eha@deif.com>
    > ---
    > drivers/net/phy/dp83640.c | 17 +++++++++++++++++
    > 1 file changed, 17 insertions(+)
    >
    > diff --git a/drivers/net/phy/dp83640.c b/drivers/net/phy/dp83640.c
    > index 654f42d00092..48403170096a 100644
    > --- a/drivers/net/phy/dp83640.c
    > +++ b/drivers/net/phy/dp83640.c
    > @@ -1207,6 +1207,22 @@ static void dp83640_remove(struct phy_device *phydev)
    > kfree(dp83640);
    > }
    >
    > +static int dp83640_soft_reset(struct phy_device *phydev)
    > +{
    > + int ret;
    > +
    > + ret = genphy_soft_reset(phydev);
    > + if (ret < 0)
    > + return ret;
    > +
    > + /* From DP83640 datasheet: "Software driver code must wait 3 us
    > + * following a software reset before allowing further serial MII
    > + * operations with the DP83640." */
    > + udelay(3);

    Hi Esben

    The accuracy of udelay() is not guaranteed. So you probably want to be
    a bit pessimistic, and use 10.

    Andrew

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