Re: [PATCH v2 net-next 1/5] net: fec: use a member variable for maximum buffer size

[Shenwei Wang]

> -----Original Message-----
> From: Andrew Lunn <andrew@xxxxxxx>
> Sent: Thursday, August 21, 2025 1:56 PM
> To: Shenwei Wang <shenwei.wang@xxxxxxx>
> Cc: Wei Fang <wei.fang@xxxxxxx>; Andrew Lunn <andrew+netdev@xxxxxxx>;
> David S. Miller <davem@xxxxxxxxxxxxx>; Eric Dumazet
> <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni
> <pabeni@xxxxxxxxxx>; Alexei Starovoitov <ast@xxxxxxxxxx>; Daniel Borkmann
> <daniel@xxxxxxxxxxxxx>; Jesper Dangaard Brouer <hawk@xxxxxxxxxx>; John
> Fastabend <john.fastabend@xxxxxxxxx>; Clark Wang
> <xiaoning.wang@xxxxxxx>; Stanislav Fomichev <sdf@xxxxxxxxxxx>;
> imx@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; dl-
> linux-imx <linux-imx@xxxxxxx>
> Subject: [EXT] Re: [PATCH v2 net-next 1/5] net: fec: use a member variable for
> maximum buffer size
> 
> > @@ -1145,9 +1145,12 @@ static void
> >  fec_restart(struct net_device *ndev)
> >  {
> >       struct fec_enet_private *fep = netdev_priv(ndev);
> > -     u32 rcntl = OPT_FRAME_SIZE | FEC_RCR_MII;
> > +     u32 rcntl = FEC_RCR_MII;
> >       u32 ecntl = FEC_ECR_ETHEREN;
> >
> > +     if (fep->max_buf_size == OPT_FRAME_SIZE)
> > +             rcntl |= (fep->max_buf_size << 16);
> 
> I was expecting something like s/OPT_FRAME_SIZE/fep->max_buf_size/g
> 
> This is introducing extra logic. I think the if (...) belongs in another patch. The
> assignment is however what i expected.

We just had an internal discussion and found that updating the macro definition is the simplest 
and most straightforward solution, as shown below. With this change, the above modifications 
are no longer necessary.

-#define        OPT_FRAME_SIZE  (PKT_MAXBUF_SIZE << 16)
+#define        OPT_FRAME_SIZE  (fep->max_buf_size << 16)
 #else
 #define        OPT_FRAME_SIZE  0

Thanks,
Shenwei

> 
>     Andrew
> 
> ---
> pw-bot: cr