From: David Miller <davem@davemloft.net>
To: andrew@lunn.ch
Cc: netdev@vger.kernel.org, cphealy@gmail.com, fugang.duan@nxp.com,
leonard.crestez@nxp.com
Subject: Re: [PATCH net-next] net: ethernet: fec: Prevent MII event after MII_SPEED write
Date: Tue, 28 Apr 2020 14:33:39 -0700 (PDT) [thread overview]
Message-ID: <20200428.143339.1189475969435668035.davem@davemloft.net> (raw)
In-Reply-To: <20200428175833.30517-1-andrew@lunn.ch>
From: Andrew Lunn <andrew@lunn.ch>
Date: Tue, 28 Apr 2020 19:58:33 +0200
> The change to polled IO for MDIO completion assumes that MII events
> are only generated for MDIO transactions. However on some SoCs writing
> to the MII_SPEED register can also trigger an MII event. As a result,
> the next MDIO read has a pending MII event, and immediately reads the
> data registers before it contains useful data. When the read does
> complete, another MII event is posted, which results in the next read
> also going wrong, and the cycle continues.
>
> By writing 0 to the MII_DATA register before writing to the speed
> register, this MII event for the MII_SPEED is suppressed, and polled
> IO works as expected.
>
> Fixes: 29ae6bd1b0d8 ("net: ethernet: fec: Replace interrupt driven MDIO with polled IO")
> Reported-by: Andy Duan <fugang.duan@nxp.com>
> Suggested-by: Andy Duan <fugang.duan@nxp.com>
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Applied to net-next, thanks.
next prev parent reply other threads:[~2020-04-28 21:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 17:58 [PATCH net-next] net: ethernet: fec: Prevent MII event after MII_SPEED write Andrew Lunn
2020-04-28 18:01 ` Andrew Lunn
2020-04-29 1:39 ` [EXT] " Andy Duan
2020-04-28 21:33 ` David Miller [this message]
2020-04-29 1:55 ` Andy Duan
2020-04-29 3:34 ` David Miller
2020-04-29 3:43 ` Andy Duan
2020-04-29 14:11 ` Andrew Lunn
2020-04-29 19:16 ` David Miller
2020-04-29 1:53 ` [EXT] " Andy Duan
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