Hello Harald, On Fri, Nov 27, 2015 at 11:02:54AM +0100, Uwe Kleine-König wrote: > On Thu, Nov 26, 2015 at 02:39:45PM +0100, Harald Geyer wrote: > > Uwe Kleine-König writes: > > > On Wed, Oct 07, 2015 at 12:19:12PM +0000, Harald Geyer wrote: > > > > This device doesn't provide any information about boot status. > > > > As workaround we use a persitent bit to track watchdog activity. > > > > > > Hmm, so you set a bit in a persistent register iff the watchdog is > > > running. And if that bit is set during probe you assume the watchdog > > > reset the machine. But this also happens, when the user presses the > > > reset button which makes the detection unreliable. > > > > Yes, kind of. I'm using this driver on an imx233-olinuxino, where the > > reset button causes the device to power cycle and thus clears the > > persitent bit. So I can't test your case, but surely there are some paths > > into reset, that don't clear the bit and cause false positives. > > OK, I found a i.MX28 machine in our repository: > > barebox# mw 0x80056080 0xbabecafe > barebox# boot > ... > linux# reboot > barebox# md 0x80056080+4 > 80056080: babecafe > > After a power cycle the value disappears (I didn't check the details, if > there is a battery it might be empty). > > > I have considered gathering some additional information from the > > power subsystem to refine the result, but decided that it's not > > worth the complexity. Since the power system is a different silicon > > block, we can't rely on it being available and would need to provide > > a fall back implementation anyway. > > It would be really nice to get some details about boot rom usage of the > persistent flags in use. I'd expect that these allow to determine the > boot source. A colleague just hinted me to http://git.pengutronix.de/?p=barebox.git;a=blob;f=drivers/watchdog/im28wd.c;h=3510776a3afc8aaf113eee995900b099c12c2be9;hb=HEAD which contains a few bit definitions for the i.MX28. Maybe they can help you to understand your machine better?! At a quick glance there is nothing that helps you to determine the boot reason, but still it might contain a few interesting things. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
