netdev - Re: [PATCH v2] mdio: aspeed: Fix "Link is Down" issue

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Message-ID: <YZ+h7qXTLvRRXpj0@lunn.ch>
Date:   Thu, 25 Nov 2021 15:47:10 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Dylan Hung <dylan_hung@...eedtech.com>
Cc:     linux-kernel@...r.kernel.org, linux-aspeed@...ts.ozlabs.org,
        linux-arm-kernel@...ts.infradead.org, netdev@...r.kernel.org,
        andrew@...id.au, joel@....id.au, kuba@...nel.org,
        davem@...emloft.net, linux@...linux.org.uk, hkallweit1@...il.com,
        BMC-SW@...eedtech.com, stable@...r.kernel.org
Subject: Re: [PATCH v2] mdio: aspeed: Fix "Link is Down" issue

On Thu, Nov 25, 2021 at 10:44:32AM +0800, Dylan Hung wrote:
> The issue happened randomly in runtime.  The message "Link is Down" is
> popped but soon it recovered to "Link is Up".
> 
> The "Link is Down" results from the incorrect read data for reading the
> PHY register via MDIO bus.  The correct sequence for reading the data
> shall be:
> 1. fire the command
> 2. wait for command done (this step was missing)
> 3. wait for data idle
> 4. read data from data register
> 
> Fixes: f160e99462c6 ("net: phy: Add mdio-aspeed")
> Cc: stable@...r.kernel.org
> Reviewed-by: Joel Stanley <joel@....id.au>
> Signed-off-by: Dylan Hung <dylan_hung@...eedtech.com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew