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Subject: Re: Issue with RTL8111 NIC after upgrade to kernel 4.19
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Norbert Jurkeit <norbert.jurkeit@web.de>, nic_swsd@realtek.com,
        Florian Fainelli <f.fainelli@gmail.com>, davem@davemloft.net,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        michael.wiktowy@gmail.com, jcline@redhat.com,
        marc.c.dionne@gmail.com
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 <20181121202034.GA10697@lunn.ch>
From:   Heiner Kallweit <hkallweit1@gmail.com>
Message-ID: <eda84d0b-2d9f-07ae-34a1-767bc5200964@gmail.com>
Date:   Wed, 21 Nov 2018 21:32:21 +0100
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On 21.11.2018 21:20, Andrew Lunn wrote:
>> request_module() is supposed to be synchronous, however after some
>> reading this may not be 100% guaranteed. Maybe the module init
>> function on some systems isn't finished yet when request_module()
>> returns. As a result the genphy driver may be used instead of
>> the PHY version-specific driver.
> 
> Hi Heiner
> 
> That would be true for all PHYs i think. We would of noticed this
> problem with other systems using other PHY drivers.
> 
> 	Andrew
> 
It could be a timing issue affecting certain systems only. At least
for now I don't have a good explanation why loading the module via
request_module() and loading it upfront manually makes a difference.

One affected user just reported the PHY to be a RTL8211B. This is
what I expected, because this PHY crashes when writing to the MMD
registers (the MMD registers are used otherwise by this PHY).
See also commit 0231b1a074c6 ("net: phy: realtek: Use the dummy
stubs for MMD register access for rtl8211b").

Let's see whether the other affected systems use the same PHY
version.

Heiner