netdev - Re: [PATCH 1/2] net: mvneta: remove bogus use of

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Message-ID: <CAPv3WKdv4tO7p07w0Ynczq66z+Jq13wbYEwriNY19PWgTjdieQ@mail.gmail.com>
Date:   Thu, 20 Jul 2017 18:01:04 +0200
From:   Marcin Wojtas <mw@...ihalf.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Gregory CLEMENT <gregory.clement@...e-electrons.com>,
        netdev@...r.kernel.org,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>
Subject: Re: [PATCH 1/2] net: mvneta: remove bogus use of

Hi Rob,

I somehow missed this patch.

2017-07-20 17:06 GMT+02:00 Gregory CLEMENT <gregory.clement@...e-electrons.com>:
> Hi Rob,
>
>  On jeu., juil. 20 2017, Rob Herring <robh@...nel.org> wrote:
>
> (Adding Marcin in CC who wrote this part of code)
>
>> Nothing sets ever sets data, so it is always NULL. Remove it as this is
>> the only user of data ptr in the whole kernel, and it is going to be
>> removed from struct device_node.
>
> Actually the use of device_node.data ptr is not bogus and it is set in
> mvneta_bm_probe:
> http://elixir.free-electrons.com/linux/latest/source/drivers/net/ethernet/marvell/mvneta_bm.c#L433
>
> Your patch will break the BM support on this driver. So if you need to
> remove this data ptr, then you have to offer an alternative for it.

Exactly, this breaks NETA operation with BM block. The data is set in:

dn->data = priv;
platform_set_drvdata(pdev, priv);

At the time I couldn't have found out a nicer solution to make work
two different HW blocks (network controller and buffer manager). There
was once a patchset enabling calling another driver's probe basing on
the phandle and of_node information, but after it reached ~v7 it
eventually didn't make it to the tree. Do you any way for solving such
dependencies, if you really want to get rid of this field?

Best regards,
Marcin

>
> Thanks,
>
> Gregory
>
>>
>> Cc: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
>> Signed-off-by: Rob Herring <robh@...nel.org>
>> ---
>> Probably there's a better fix here to actually enable the h/w buffer
>> manager.
>>
>> I intend to take this thru the DT tree as patch 2 is dependent on this.
>>
>> Rob
>>
>>  drivers/net/ethernet/marvell/mvneta.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
>> index 0aab74c2a209..5624f4b49f9d 100644
>> --- a/drivers/net/ethernet/marvell/mvneta.c
>> +++ b/drivers/net/ethernet/marvell/mvneta.c
>> @@ -4296,8 +4296,8 @@ static int mvneta_probe(struct platform_device *pdev)
>>
>>       /* Obtain access to BM resources if enabled and already initialized */
>>       bm_node = of_parse_phandle(dn, "buffer-manager", 0);
>> -     if (bm_node && bm_node->data) {
>> -             pp->bm_priv = bm_node->data;
>> +     if (bm_node) {
>> +             pp->bm_priv = NULL;
>>               err = mvneta_bm_port_init(pdev, pp);
>>               if (err < 0) {
>>                       dev_info(&pdev->dev, "use SW buffer management\n");
>> --
>> 2.11.0
>>
>
> --
> Gregory Clement, Free Electrons
> Kernel, drivers, real-time and embedded Linux
> development, consulting, training and support.
> http://free-electrons.com