From mboxrd@z Thu Jan 1 00:00:00 1970 From: Erwin Rol Subject: Re: at91sam9260 MACB problem with IP fragmentation Date: Thu, 20 Dec 2012 10:17:49 +0100 Message-ID: <50D2D7BD.3030801@erwinrol.com> References: <50C08233.9030905@erwinrol.com> <50C09D2E.8050608@atmel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, Havard Skinnemoen , linux-arm-kernel , matteo.fortini@sadel.it, netdev To: Nicolas Ferre Return-path: In-Reply-To: <50C09D2E.8050608@atmel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hallo Nicolas, On 6-12-2012 14:27, Nicolas Ferre wrote: > Erwin, > > On 12/06/2012 12:32 PM, Erwin Rol : >> Hello Nicolas, Havard, all, >> >> I have a very obscure problem with a at91sam9260 board (almost 1 to 1 >> copy of the Atmel EK). >> >> The MACB seems to stall when I use large (>2 * MTU) UDP datagrams. The >> test case is that a udp echo client (PC) sends datagrams with increasing >> length to the AT91 until the max length of the UDP datagram is reached. >> When there is no IP fragmentation everything is fine, but when the >> datagrams are starting to get fragmented the AT91 will not reply >> anymore. But as soon as some network traffic happens it goes on again, >> and non of the data is lost. >> I tried several kernels including the test version from Nicolas that he >> posted on LKML in October. They all show the same effect. > > [..] > > It seems that Matteo has the same behavior: check here: > http://www.spinics.net/lists/netdev/msg218951.html I tried Matteo's patch and it seems to work. But I don't know if the patch is really the right solution. I checked again with wireshark and it really seems the sending that stalls not the receiving. But as soon as a ethernet frame is received the sending "un-stalls". So maybe the patch just causes an MACB IRQ at certain moments that causes the sending to continue? > I am working on the macb driver right now, so I will try to reproduce > and track this issue on my side. Any luck reproducing it ? - Erwin