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From: Andrew Lunn <andrew@lunn.ch>
To: Andy Duan <fugang.duan@nxp.com>
Cc: netdev <netdev@vger.kernel.org>, Chris Healy <cphealy@gmail.com>,
	Andy Duan <fugang.duan@nxp.com>,
	Leonard Crestez <leonard.crestez@nxp.com>
Subject: Re: [PATCH net-next] net: ethernet: fec: Prevent MII event after MII_SPEED write
Date: Tue, 28 Apr 2020 20:01:44 +0200	[thread overview]
Message-ID: <20200428180144.GA30612@lunn.ch> (raw)
In-Reply-To: <20200428175833.30517-1-andrew@lunn.ch>

On Tue, Apr 28, 2020 at 07:58:33PM +0200, Andrew Lunn wrote:
> 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.

Hi Andy

Could you get your LAVA instances to test this? Or do we need to wait
for it to make its way into net-next?

Thanks
	Andrew

  reply	other threads:[~2020-04-28 18:01 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 [this message]
2020-04-29  1:39   ` [EXT] " Andy Duan
2020-04-28 21:33 ` David Miller
2020-04-29  1:55   ` [EXT] " 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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