netdev - RE: [PATCH] fsl/fman: remove of

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Message-ID: <AM5PR0402MB26914CBD37E3F28C17562258EC720@AM5PR0402MB2691.eurprd04.prod.outlook.com>
Date:   Tue, 3 Oct 2017 08:49:31 +0000
From:   Madalin-cristian Bucur <madalin.bucur@....com>
To:     David Miller <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] fsl/fman: remove of_node

> -----Original Message-----
> From: David Miller [mailto:davem@...emloft.net]
> Sent: Tuesday, October 03, 2017 2:05 AM
> To: Madalin-cristian Bucur <madalin.bucur@....com>
> Subject: Re: [PATCH] fsl/fman: remove of_node
> 
> From: Madalin Bucur <madalin.bucur@....com>
> Date: Mon, 2 Oct 2017 13:31:37 +0300
> 
> > The FMan MAC driver allocates a platform device for the Ethernet
> > driver to probe on. Setting pdev->dev.of_node with the MAC node
> > triggers the MAC driver probing of the new platform device. While
> > this fails quickly and does not affect the functionality of the
> > drivers, it is incorrect and must be removed. This was added to
> > address a report that DSA code using of_find_net_device_by_node()
> > is unable to use the DPAA interfaces. Error message seen before
> > this fix:
> >
> > fsl_mac dpaa-ethernet.0: __devm_request_mem_region(mac) failed
> > fsl_mac: probe of dpaa-ethernet.0 failed with error -16
> >
> > Signed-off-by: Madalin Bucur <madalin.bucur@....com>
> 
> Is the DSA issue no longer something we need to be concerned
> about?  If not, why?  You have to explain this.

My patch removes the of_node that was set to a device that was not an
of_device, preventing duplicated probing of both the real of_device
and the "fake" one created through this assignment.

I understand that the DSA issue that triggered the initial change
was related to DSA finding the network devices using 
of_find_net_device_by_node(), something that will not work for the
DPAA case where the netdevice does not have an of_node. I do not know
enough about DSA to come up with a solution for this problem now.
Andrew, Florian, can you please comment on this?

Thanks,
Madalin