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Message-ID: <CAMuHMdUwDxb5K+Q335isLE-+HLwbwGSksp0KYmGoaXGYQmSiug@mail.gmail.com>
Date: Mon, 14 Apr 2014 18:48:34 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Ben Dooks <ben.dooks@...ethink.co.uk>
Cc: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Linux-sh list <linux-sh@...r.kernel.org>,
magnus.damm@...nsource.se,
Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@...esas.com>
Subject: Re: [RFC] sh_eth: use RNC mode for R8A7790
On Mon, Apr 14, 2014 at 6:35 PM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
> On Mon, Apr 14, 2014 at 2:47 PM, Ben Dooks <ben.dooks@...ethink.co.uk> wrote:
>> On 28/03/14 20:38, Sergei Shtylyov wrote:
>>> On 03/28/2014 07:46 PM, Ben Dooks wrote:
>>>> The current behaviour of the sh_eth driver is not to use the RNC bit
>>>> for the receive ring. This means that every packet recieved is not only
>>>> generating an IRQ but it also stops the receive ring DMA as well until
>>>> the driver re-enables it after unloading the packet.
>>>
>>>> This means that a number of the following errors are generated due to
>>>> the receive packet FIFO overflowing due to nowhere to put packets:
>>>
>>>> net eth0: Receive FIFO Overflow
>>>
>>>> Setting the RMCR_RNC configuration has so far been tested with an NFS
>>>> root filesystem and the driver has not failed yet. It is not yet known
>>>> why this is not set for R8A779x operation
>>>
>>> The reason is simple: it's not set on almost all 100 Mbs devices
>>> except SH7757 (and most recently added R7S72100), so this was a matter
>>> of copy-paste. I've had setting this bit on at least R-Car devices on my
>>> aganda for some time but couldn't get to it yet.
>>>
>>>> (Feedback on this issue or other testing is welcome)
>>>
>>> OK, I'll try it with netperf UDP test known to generate handful of
>>> the aforementioned errors, when I have time.
>>
>> Has anyone had time to look at this?
>
> I gave it a try on Koelsch (it does apply to r8a7791, too, right?), and didn't
> see any good or ill effects. Just using NFS root and generating some I/O,
> so nothing fancy.
FWIW, I still have "renesas,no-ether-link" in the ethernet node in DT.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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