From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [RFC] sh_eth: use RNC mode for R8A7790 Date: Sat, 26 Apr 2014 03:54:08 +0400 Message-ID: <535AF5A0.6010206@cogentembedded.com> References: <1396025185-7911-1-git-send-email-ben.dooks@codethink.co.uk> <5335DDC7.8040400@cogentembedded.com> <534BD8F9.5080105@codethink.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , Linux-sh list , magnus.damm@opensource.se, Nobuhiro Iwamatsu To: Geert Uytterhoeven , Ben Dooks Return-path: In-Reply-To: Sender: linux-sh-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hello. On 04/14/2014 08:48 PM, Geert Uytterhoeven 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. You shouldn't need it anymore if you're using recent devel branch of the renesas.git repo: it already has the necessary PHY driver and device tree changes to avoid the issue which specifying that prop fixed. > Gr{oetje,eeting}s, WBR, Sergei