netdev - Re: IMX6 FEC connection drops occasionally with 'MDIO read timeout'

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Message-ID: <CAJ+vNU1sBrtno7TiXieN0jKaoNXW8EdKtKO49=FfXy8JNSmd6A@mail.gmail.com>
Date:   Wed, 12 Apr 2017 09:54:12 -0700
From:   Tim Harvey <tharvey@...eworks.com>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>, netdev <netdev@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Fugang Duan <fugang.duan@....com>,
        Koen Vandeputte <koen.vandeputte@...ntric.com>
Subject: Re: IMX6 FEC connection drops occasionally with 'MDIO read timeout'

On Wed, Apr 12, 2017 at 9:26 AM, Fabio Estevam <festevam@...il.com> wrote:
> Hi Tim,
>
> On Wed, Apr 12, 2017 at 1:15 PM, Tim Harvey <tharvey@...eworks.com> wrote:
>>
>> Andrew,
>>
>> Thanks for the reply. Your talking about suspend/resume power
>> management right? The users reporting this were not using
>> suspend/resume.
>>
>> With regards to clock are you talking about the IPG clock? Is there
>> any other way that would get turned off other than fec suspend/resume?
>
> Yes, through pm_runtime.
>
> Can you check if this quick debug change help?
>
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -3606,8 +3606,6 @@ static int __maybe_unused
> fec_runtime_suspend(struct device *dev)
>         struct net_device *ndev = dev_get_drvdata(dev);
>         struct fec_enet_private *fep = netdev_priv(ndev);
>
> -       clk_disable_unprepare(fep->clk_ipg);
> -
>         return 0;
>  }
>
>
> If you don't see the problem with it, then it means we need to fix the
> pm runtime support in this driver.
>
> Most likely pm runtime is turning off the clocks when it should not.

Fabio,

Ok, I understand now. We will disable the IPG clock disable and see if
that makes a difference.

Tim