Date: Mon, 25 Jul 2016 09:42:24 -0700 From: Thomas Skibo <thomasskibo@yahoo.com> To: Lee D <embaudarm@gmail.com> Cc: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: Questions about writing custom boot loader, Zynq, Zybo Message-ID: <F81463B6-4312-44B6-AF04-1CDFE2E2A2CB@yahoo.com> In-Reply-To: <CANC_bnMY0ZgZQTgE94bXuTp8xQ7Um7cALj39mLPQgDYumJPOwQ@mail.gmail.com> References: <C91EF32E-7131-4E03-8FE4-758C53613C7D@yahoo.com> <CANC_bnMY0ZgZQTgE94bXuTp8xQ7Um7cALj39mLPQgDYumJPOwQ@mail.gmail.com>
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> On Jul 24, 2016, at 3:25 PM, Lee D <embaudarm@gmail.com> wrote: >=20 > Thanks for the tips. The RS232 issue was simple. Xilinx (or possibly = Digilent) changed the default clock for the serial port from 50MHz to = 100MHz. I made the correction in the DTS file and now the baud rate is = correct. I hadn=E2=80=99t noticed they changed it. My u-boot still uses the = 50Mhz so it matches the DTS file. What really ought to happen is the slcr driver should determine the = frequency of all the clocks derived from ps_clk so the only thing the = DTS file needs to provide is the ps_clk frequency. I=E2=80=99ll have to = do that anyway if we move over to using GNU DTS files. >=20 > Do you know if passing a boot params structure in R0 is necessary for = the kernel to boot? =20 >=20 > I still can't seem to get past that timer message. This is what I've = done: >=20 > 1. Made sure I am working with a bare default Zybo config generated in = Vivado 2016.2 >=20 > 2. compared my ps_init.[ch] to the one you pointed me to. There were = no significant differences except for the RS232 clock rate. I had some = MIO pins configured, and my DRAM timings were different. my DRAM works = fine with standalone apps so I assume that was a tweak made by Digilent = and not an issue. >=20 > 3. added printf's to inittimecounter() in src/sys/kern/kern_tc.c. It = is clear that it completes normally. Also the timer appears to be = running. =20 >=20 > However that function is part of the kernel init sequence (SYSINIT = macro), so I don't know what is getting called next.=20 >=20 > 4. I removed the ehci device from the DTS, and commented out all USB = related entries in the zybo kernel config file. Still it freezes after = that timer message. So probably not USB related. >=20 > 5. Checked to make sure that the USB3320 chip is not being held in = reset by the GPIO line. >=20 > My next steps are: >=20 > 1. keep digging through the kernel and placing printfs to pinpoint = where it is failing. >=20 > 2. try the ps_init.[ch] files you showed me in my project, even though = they shouldn't make any difference. >=20 > 3. try passing a boot params structure in r0.=20 >=20 > Thanks again for pointing me to the original ps_init files, that was = very helpful to be able to see those. >=20 > Lee >=20 =E2=80=94=E2=80=94 Thomas Skibo thomasskibo@yahoo.com
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