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Date:      Tue, 26 Nov 2019 22:03:30 +0000
From:      James Shuriff <james@opentech.cc>
To:        "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org>
Subject:   rpi3 clock drift
Message-ID:  <MWHPR06MB3134CD05551D36CC3B45D368AA450@MWHPR06MB3134.namprd06.prod.outlook.com>

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My Raspberry Pi 3 Model B is having some serious clock drift issues. Ntpd doesn't function even with ntpd_sync_on_start, which calls ntpd with -g and allows the initial adjustment to exceed the panic threshold. This doesn't help me much because the system will continue to drift very quickly and that option only helps for the initial adjustment.

I was thinking of ordering an I2C RTC but I'm unsure how to make FreeBSD aware of the clock.

There is a file in the Raspberry Pi firmware repo called i2c-rtc.dtbo and it contains defs for clocks like DS1307 so I am assuming I can add this to config.txt, build U-Boot with CONFIG_RTC_DS1307 (or whatever model), and build the kernel with device support for the clock but I'm not completely sure if I'm going about this the right way. Beyond just getting FreeBSD to see the clock I'm unsure how to tell FreeBSD to use it. Any advice?

Thanks,

- James Shuriff

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