netdev - Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: add RXNFC support

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Message-ID: <20190908085529.GB28580@lunn.ch>
Date:   Sun, 8 Sep 2019 10:55:29 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Vivien Didelot <vivien.didelot@...il.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, f.fainelli@...il.com
Subject: Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: add RXNFC support

On Sat, Sep 07, 2019 at 05:25:10PM -0400, Vivien Didelot wrote:
> Hi Andrew,
> 
> On Sat, 7 Sep 2019 22:32:56 +0200, Andrew Lunn <andrew@...n.ch> wrote:
> > > +	policy = devm_kzalloc(chip->dev, sizeof(*policy), GFP_KERNEL);
> > > +	if (!policy)
> > > +		return -ENOMEM;
> > 
> > I think this might be the first time we have done dynamic memory
> > allocation in the mv88e6xxx driver. It might even be a first for a DSA
> > driver?
> > 
> > I'm not saying it is wrong, but maybe we should discuss it. 
> > 
> > I assume you are doing this because the ATU entry itself is not
> > sufficient?
> > 
> > How much memory is involved here, worst case? I assume one struct
> > mv88e6xxx_policy per ATU entry? Which you think is too much to
> > allocate as part of chip? I guess most users will never use this
> > feature, so for most users it would be wasted memory. So i do see the
> > point for dynamically allocating it.
> 
> A layer 2 policy is not limited to the ATU. It can also be based on a VTU
> entry, on the port's Etype, or frame's Etype. We can have 0, 1 or literally
> thousands of policies programmed by the user.

O.K, then it has to by dynamic memory.

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

    Andrew