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Message-Id: <20140603.192917.1491089262510239439.davem@davemloft.net>
Date: Tue, 03 Jun 2014 19:29:17 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: ben.dooks@...ethink.co.uk
Cc: linux-kernel@...ethink.co.uk, netdev@...r.kernel.org,
nobuhiro.iwamatsu.yj@...esas.com, magnus.damm@...nsource.se,
horms@...ge.net.au, yoshihiro.shimoda.uh@...esas.com,
cm-hiep@...so.co.jp
Subject: Re: [RFC/PATCH v3] sh_eth: use RNC mode for packet reception
From: Ben Dooks <ben.dooks@...ethink.co.uk>
Date: Tue, 3 Jun 2014 12:21:13 +0100
> 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
>
> Since feedback from Yoshihiro Shimoda shows that every supported LSI
> for this driver should have the bit enabled it seems the best way is
> to remove the RMCR default value from the per-system data and just
> write it when initialising the RMCR value. This is discussed in
> the message (http://www.spinics.net/lists/netdev/msg284912.html).
>
> I have tested the RMCR_RNC configuration with NFS root filesystem and
> the driver has not failed yet. There are further test reports from
> Sergei Shtylov and others for both the R8A7790 and R8A7791.
>
> There is also feedback fron Cao Minh Hiep[1] which reports the
> same issue in (http://comments.gmane.org/gmane.linux.network/316285)
> showing this fixes issues with losing UDP datagrams under iperf.
>
> Tested-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
> Signed-off-by: Ben Dooks <ben.dooks@...ethink.co.uk>
Applied.
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