netdev - Re: [PATCH net] net: phy: replace preliminary fix for PHY driver sometimes not binding to the device

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Message-ID: <c5271354-e489-6736-a238-7d94d20cd7e5@gmail.com>
Date:   Tue, 25 Dec 2018 16:17:13 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Miller <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Norbert Jurkeit <norbert.jurkeit@....de>,
        Frank Crawford <frank@...wford.emu.id.au>
Subject: Re: [PATCH net] net: phy: replace preliminary fix for PHY driver
 sometimes not binding to the device

On 24.12.2018 12:21, Heiner Kallweit wrote:
> phy_device_create() uses request_module() to load the PHY driver module
> based on the PHY ID of the device. There is some timing issue which
> sometimes prevents the PHY driver to bind to the device. In such cases
> the genphy driver is used what can cause problems if genphy isn't
> compatible with the respective PHY.
> It turned out that the first fix can fix the issue in some but not all
> cases. Moving the call to device_initialize() before the call to
> request_module() was reported to fix the issue.
> I can't explain where the root cause of the issue is and why this fix
> works. AFAICS device_initialize() just initializes the device struct
> w/o doing anything that could interfere with e.g. bus_add_driver().
> This patch removes the first preliminary fix attempt.
> 
> Reference:
> https://bugzilla.redhat.com/show_bug.cgi?id=1650984
> 
> Fixes: c85ddecae6e5 ("net: phy: add workaround for issue where PHY driver doesn't bind to the device")
> Tested-by: Norbert Jurkeit <norbert.jurkeit@....de>
> Tested-by: Frank Crawford <frank@...wford.emu.id.au>
> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> ---
[..]

I got a report from a user that for him the issue still isn't fixed.
So we need to check alternative approaches. Still I think the root cause
must be in the driver core, therefore set Greg and Rafael on the list.
Could you please wait with applying this patch?

Thanks, Heiner