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From:   Marcin Wojtas <mw@semihalf.com>
Date:   Mon, 17 Dec 2018 00:25:58 +0100
Message-ID: <CAPv3WKfz4AkODzJ+gsV=u6ve5YnZEdUhZF5+VmFPQa4mp9okUw@mail.gmail.com>
Subject: Re: [PATCH net] net: mvneta: fix operation for 64K PAGE_SIZE
To:     David Miller <davem@davemloft.net>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        netdev <netdev@vger.kernel.org>,
        Russell King - ARM Linux <linux@armlinux.org.uk>,
        Maxime Chevallier <maxime.chevallier@bootlin.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        =?UTF-8?Q?Gr=C3=A9gory_Clement?= <gregory.clement@bootlin.com>,
        Antoine Tenart <antoine.tenart@bootlin.com>,
        Stefan Chulski <stefanc@marvell.com>, nadavh@marvell.com,
        Grzegorz Jaszczyk <jaz@semihalf.com>
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Hi David,

niedz., 16 gru 2018 o 21:41 David Miller <davem@davemloft.net> napisa=C5=82=
(a):
>
> From: Marcin Wojtas <mw@semihalf.com>
> Date: Tue, 11 Dec 2018 13:56:49 +0100
>
> > Recent changes in the mvneta driver reworked allocation
> > and handling of the ingress buffers to use entire pages.
> > Apart from that in SW BM scenario the HW must be informed
> > via PRXDQS about the biggest possible incoming buffer
> > that can be propagated by RX descriptors.
> >
> > The BufferSize field was filled according to the MTU-dependent
> > pkt_size value. Later change to PAGE_SIZE broke RX operation
> > when usin 64K pages, as the field is simply too small.
> >
> > This patch conditionally limits the value passed to the BufferSize
> > of the PRXDQS register, depending on the PAGE_SIZE used.
> > On the occasion remove now unused frag_size field of the mvneta_port
> > structure.
> >
> > Fixes: 562e2f467e71 ("net: mvneta: Improve the buffer allocation method=
 for SWBM")
> > Signed-off-by: Marcin Wojtas <mw@semihalf.com>
>
> The discussion died on this, but the bug should be fixed.
>
> So in the short term I am applying this and queueing it up for v4.19
> -stable.
>
> Thanks.

Thanks. Indeed, the patch is valid as a fix for current version of SW
BM. However, because this concept is broken, I will rework it and
submit patch/patches some time early 2019.

Best regards,
Marcin