From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <52E56221.5070005@xenomai.org> Date: Sun, 26 Jan 2014 20:29:37 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <52DF9C5F.70005@geral.com> <52DFAA18.6080703@xenomai.org> <52DFAD29.4000800@geral.com> <52DFB2DE.4050501@xenomai.org> <52DFC734.2090906@geral.com> <52DFC80D.6050101@xenomai.org> <52DFCFDE.9060700@geral.com> <52DFD1B0.6070303@xenomai.org> <52E5616F.90002@grandegger.com> In-Reply-To: <52E5616F.90002@grandegger.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Subject: Re: [Xenomai] imx28 rtcan flexcan system freezes List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wolfgang Grandegger Cc: xenomai@xenomai.org On 01/26/2014 08:26 PM, Wolfgang Grandegger wrote: > On 01/22/2014 03:12 PM, Gilles Chanteperdrix wrote: >> On 01/22/2014 03:04 PM, Alexandre COFFIGNAL wrote: >>> >>> Le 22/01/2014 14:30, Gilles Chanteperdrix a écrit : >>>> On 01/22/2014 02:27 PM, Alexandre COFFIGNAL wrote: >>>>> >>>>> Le 22/01/2014 13:00, Gilles Chanteperdrix a écrit : >>>>>> On 01/22/2014 12:36 PM, Alexandre COFFIGNAL wrote: >>>>>>>>> + cf->data[3]=((data0 >> 0) & 0xFF) ; >>>>>>>>> + cf->data[2]=((data0 >> 8) & 0xFF) ; >>>>>>>>> + cf->data[1]=((data0 >> 16) & 0xFF) ; >>>>>>>>> + cf->data[0]=((data0 >> 24) & 0xFF) ; >>>>>>>>> + cf->data[7]=((data1 >> 0) & 0xFF) ; >>>>>>>>> + cf->data[6]=((data1 >> 8) & 0xFF) ; >>>>>>>>> + cf->data[5]=((data1 >> 16) & 0xFF) ; >>>>>>>>> + cf->data[4]=((data1 >> 24) & 0xFF) ; >>>>>>>>> >>>>>>>>> rtcan flexcan works perfectly. >>>>>>>>> is anyone know what is the problem with first instructions ? >>>>>>>> Probably mb->data does not have the right alignment. Could you not >>>>>>>> arrange to get it properly aligned? Failing that, you should use >>>>>>>> put_unaligned instead of open coding it. >>>>>>>> >>>>>>>> >>>>>>> here structures used in flexcan driver, it seem to be aligned >>>>>> >>>>>> I am talking about the alignment of cf->data, since obviously, that is >>>>>> the one which is causing problems. >>>>>> >>>>>> >>>>> Thank a lot, put_unaligned fix this issue if you want, i can send a >>>>> path >>>>> >>>> >>>> The other solution (getting cf->data to be properly aligned) would be >>>> more efficient, why is not it possible to get cf->data properly aligned? >>>> >>> I think, i can't get cf->data to be properly aligned because "cf" is >>> receive internal frame representation within the ring buffer >>> of a struct rtcan_socket and struct rtcan_rb_frame is a generic >>> structure used in all rtcan drivers . >> >> Well, if you fix rtcan_rb_frame to be aligned, it will be aligned for >> all drivers, so that looks like a worthwile improvement... > > I had a closer look. The CAN message (frame) queuing is optimized for > size to get as much as possible messages into the queue. Therefore the > CAN data are copied using memcpy, but only the real bytes. Directly > behind the real data is the 64 bit timestamp, if requested, which is > also not aligned. Therefore I suggest to use memcpy or byte accesses in > the flexcan driver as well. If this was a good decision is another question. Aligning the data begining costs 2 bytes by struct rtcan_rb_frame. How many such structures are there for a typical driver? -- Gilles.