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        Mon, 19 Mar 2018 08:39:40 -0400
Date: Mon, 19 Mar 2018 13:39:39 +0100
From: Andrew Lunn <andrew@lunn.ch>
To: Kevin Hao <haokexin@gmail.com>
Cc: netdev@vger.kernel.org, Florian Fainelli <f.fainelli@gmail.com>,
        Claudiu Manoil <claudiu.manoil@nxp.com>
Subject: Re: [PATCH] net: phy: realtek: Add dummy stubs for MMD register
 access for rtl8211b
Message-ID: <20180319123939.GC19795@lunn.ch>
References: <20180319120547.18707-1-haokexin@gmail.com>
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On Mon, Mar 19, 2018 at 08:05:47PM +0800, Kevin Hao wrote:
> The Ethernet on mpc8315erdb is broken since commit b6b5e8a69118
> ("gianfar: Disable EEE autoneg by default"). The reason is that
> even though the rtl8211b doesn't support the MMD extended registers
> access, it does return some random values if we trying to access
> the MMD register via indirect method. This makes it seem that the
> EEE is supported by this phy device. And the subsequent writing to
> the MMD registers does cause the phy malfunction. So add dummy stubs
> for the MMD register access to fix this issue.

Hi Kevin

The Micrel PHY has the same problem. Please add generic
genphy_read_mmd_unsupported() and genphy_write_mmd_unsupported() to
phy_device.c, and use them from both the Micrel and Realtek PHY
drivers.

Also, a return value of -EOPNOTSUPP is more appropriate.

Thanks

	Andrew