Hi Wolfgang, On Tue, Oct 27, 2009 at 06:29:57PM +0100, Wolfgang Grandegger wrote: > Luotao Fu wrote: > > Hi, > > > > I'm playing with 2.6.31 + mscan driver on a mpc5200B board the last > > days, have slightly backported the mscan driver to meet the can frame > > work in 2.6.31. Now I ran into a quite funny situation: > > > > The board is connected to a host, which has an IXXAT PCI can card > > (2.6.26 and an unknown SocketCAN version, which is more or less recent, > > since it provides sysfs entries). The host is set to a baudrate of > > 250kbit, while the target comes up with 125kbit. As soon as the host and > > target are up and running, I send a frame with cansend from the host. > > After that both sides go into bus passive, which is the expected > > behaviour. However the board seems not to be able to get out there any > > more. Turning off the interface -> change the baudrate to 250K -> > > turning on the interface went through without errors. However the board > > seems to stuck and neither sending nor receiving will work any more. I > > instrumented the mscan_set_mode() call with the attached patch and > > noticed that the RXACT is never cleared in this case any more and the > > initrq will eventually never reach. a small screenshot to make it a > > little more clear: > > ## Usually changing bitrate should read like this > > @target: /sbin/ip link set can1 type can bitrate 250000 > > changing bit rate to can1 > > [ 105.854706] ctl0: 0x10 > > [ 105.857231] ctl0: 0x2 > > ## sleep mode request is set > > [ 105.863075] ctl0: 0x3 > > ## init mode request is set > > Hm, the lines above are from a ifconfig down, right? >
Ah, je, the kernel prints are from ifconfig down. I lied a little since in the screenshot since I wrote the commands into a script. Actually I thought myself the whole time that the printks come from bitrate stuff, just like in the prehistorical old version. This was however the only untruth here. I promise. ;-) > > [ 105.888505] mpc52xx_can f0000980.can: setting BTR0=0x0a BTR1=0x18 > > ## after the mscan got stuck resetting bitrate reads like this: > > @target: /sbin/ip link set can1 type can bitrate 250000 > > changing bit rate to can1 > > [ 303.130686] ctl0: 0x50 > > [ 303.160088] ctl0: 0x52 > > [ 303.162512] ctl0: 0x52 > > [ 303.206860] mpc52xx_can f0000980.can: setting BTR0=0x0a BTR1=0x18 > > > > Seems RXACT is never cleared on the mscan side. Setting to init_mode > > will then eventually fail and the controller stucks in sleep mode. I > > can solve the problem by pulling the target from can bus and so > > cause an bus-off to restart the stuff or I restart the can controller > > on the host side. However it still feels like a bug. Two questions: > > Either a hardware or a software bug. RXACT can not be cleared by software. > Noticed that. I do think that the RXACT is triggered by the host retrying sending the message. Could this be the reason why the mscan controller got stuck? > > 1. why is the failed initrq uncatched? I doubled checked with an mscan > > driver from an reeeeal old socketcan patch(-r466) + 2.6.23, it will fail > > on spinning wait for slpak and quit there with an -ENODEV. Why is it not > > happening any more? > > Could you highlight the differences between to new and the old version? > And does the old approach fix the problem? > I mistook on this one. In the old version the do_set_mode was called while changing baudrate with INIT_MODE set. In the new version the do_set_mode is called during ifconfig down with SLEEP_MODE. Where there's no init request, there's also no error to catch. > > 2. Any hint for a possible fix the problem described above or is it more > > a conceptional question / hardware problem with mscan? > > >From time to time I have observed myself wired problems with the MSCAN > CAN state management, which I was unable to explain. I will try to > reproduce your symptoms on my setup. thx cheers Luotao Fu -- Pengutronix e.K. | Dipl.-Ing. Luotao Fu | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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