Hi Alexandre, On Thu, Jul 16, 2020 at 08:18:16PM +0200, Alexandre Belloni wrote: > On 16/07/2020 16:47:05+0200, Uwe Kleine-König wrote: > > On Thu, Aug 22, 2019 at 03:19:35PM +0200, Bruno Thomsen wrote: > > > Add partial support for the watchdog functionality of > > > both PCF2127 and PCF2129 chips. > > > > I have a board here with a pcf2127 that has the #RST pin > > not connected. > > > > The problem this creates is: The bootloader arms the SoC's watchdog and > > jumps into Linux. The pcf2127 driver happens to load first, so watchdog0 > > is provided by the RTC (but non-functional). Systemd is configured to > > feed the watchdog, but happens to feed the wrong one, so the machine > > resets shortly after it is up :-| > > > > So I wonder if we need a dt property that tells the driver if the RST > > line is connected or not. > > I guess the current solution is to set WatchdogDevice to point to a link > that is updated by udev thus ensuring it points to the correct watchdog > device regardless of the probe order. > > This would be similar to the /dev/rtc symlink, pointing to the systohc > RTC by default (even if I don't really like that heuristic). > > What you suggest is somewhat okay but doesn't really solve the issue if > both watchdogs are functional and systemd still doesn't pick the one > that is armed by the bootloader. Yes, my suggestion doesn't solve the problem "Oh, there are two watchdogs, which should I feed?". But IMHO in this case there shouldn't be a watchdog device provided at all by an RTC that can be a watchdog but isn't wired up correctly. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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