Date: Sat, 16 May 2020 23:38:53 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: freebsd-arm@FreeBSD.org Subject: Re: need help w/ Cora-Z7, XC7Z007S Zynq board Message-ID: <20200517063853.GI4213@funkthat.com> In-Reply-To: <20200516221344.GH4213@funkthat.com> References: <20200516221344.GH4213@funkthat.com>
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John-Mark Gurney wrote this message on Sat, May 16, 2020 at 15:13 -0700: > Hello, > > Recently got the Cora-Z7 board, and want to get FreeBSD working on it. > > With a bit of help from manu, I managed to get FreeBSD booting on it, > but running into issues w/ the clocks. > > The issue is that I need to set the clock-frequency for the > global-clock, otherwise I don't have an event timer and the kernel > panics. I configured it in the dts: > https://www.funkthat.com/~jmg/FreeBSD/cora-z7/zynq-coraz7.dts > > But the issue is that time passes approximately 6.25x faster than > it should. This was measured via pinging a remote host on the > board, and via another machine, observing that it was about 6.23x > difference, and noticing that 50MHz/8MHz is 6.25x. The 50 MHz > speed was selected because the Cora-Z7 user guide says that the PS_CLK > block is provided a 50 MHz clock, and the dts provided by Digilent > uses 50 MHz as well: > https://github.com/Digilent/u-boot-digilent/blob/master/arch/arm/dts/zynq-coraz7.dts#L41 After a bit of digging, I think I have found the solution. It looks like slcr is suppose to be set to the frequency of the ps clk, which is 50 MHz, and then the global_timer is suppose to be set to half the CPU clock frequency, which on this board is, I believe, 650 MHz, so using the following in the dts made things work: &slcr { clock-frequency = <50000000>; }; &global_timer { clock-frequency = <325000000>; }; ping times look good sane (after I realized that wifi has a tad slower), and I've been running ntpd for over 20 minutes, and it hasn't bombed out yet, and the offset/jitter look good. -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."
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