netdev - Re: [PATCH] net: ethernet: fec: Clear stale flag in IEVENT register before MII transfers

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Message-ID: <20201209143248.GG2611606@lunn.ch>
Date:   Wed, 9 Dec 2020 15:32:48 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Fugang Duan <fugang.duan@....com>,
        "David S. Miller" <davem@...emloft.net>, kernel@...gutronix.de,
        netdev@...r.kernel.org
Subject: Re: [PATCH] net: ethernet: fec: Clear stale flag in IEVENT register
 before MII transfers

On Wed, Dec 09, 2020 at 11:29:59AM +0100, Uwe Kleine-König wrote:
> For some mii transfers the MII bit in the event register is already set
> before a read or write transfer is started. This breaks evaluating the
> transfer's result because it is checked too early.
> 
> Before MII transfers were switched from irq to polling this was not an
> issue because then it just resulted in an irq which completed the
> mdio_done completion. This completion however was reset before each
> transfer and so the event didn't hurt.
> 
> This fixes NFS booting on an i.MX25 based machine.
> 
> Fixes: f166f890c8f0 ("net: ethernet: fec: Replace interrupt driven MDIO with polled IO")
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> ---
> Hello,
> 
> I tried (shortly) to find out what actually results in this bit being
> set because looking at f166f890c8f0 I'd say it cares enough. It's just
> proven by the real world that it's not good enough :-)
> 
> Best regards
> Uwe

Hi Uwe

Humm. This should of been fixed already. Has a patch been dropped?

Let me go look at the history.

    Andrew