Date: Sat, 5 Jan 2019 22:24:49 +0100 From: Per Hedeland <per@hedeland.org> To: Oleksandr Tymoshenko <gonzo@bluezbox.com> Cc: freebsd-arm@freebsd.org Subject: Re: i2c on RPi Zero? Message-ID: <e981729d-bb71-c74e-aaa7-86c7447b1f24@hedeland.org> In-Reply-To: <20190105195808.GA53872@bluezbox.com> References: <229e0d36-a07b-8551-9613-0bf5748352e7@hedeland.org> <dc9441e2-9858-989e-a135-3ae37de0925b@hedeland.org> <20190105195808.GA53872@bluezbox.com>
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On 2019-01-05 20:58, Oleksandr Tymoshenko wrote:
> Per Hedeland (per@hedeland.org) wrote:
>> I did a bit more testing on the Zero to see if the FreeBSD version
>> mattered:
>>
>> FreeBSD-12.0-STABLE-arm-armv6-RPI-B-20190103-r342709.img - still no
>> luck.
>>
>> FreeBSD-11.2-STABLE-arm-armv6-RPI-B-20190103-r342709.img - works!
>> (I.e. dmesg reports as below and /dev/iic{0,1} get created - I haven't
>> tested actual usage beyond having 'i2c -s' report "no devices found".)
>>
>> I guess that the i2c support hasn't been removed intentionally,
>> i.e. this seems to be a regression - or is there some additional
>> config etc required to enable it with FreeBSD-12? The iic and iicbus
>> drivers appear to be built into the kernel in both 11 and 12.
>>
>> (I haven't tested FreeBSD-12 on the Pi B, but I would guess that the
>> result will be the same as on the Zero, since it seems the hardware is
>> the same.)
>
> There was a transition in device tree files between 11 and 12.
> bcm2708-rpi-0-w.dtb has i2c nodes but they're disabled by default.
> Try editing config.txt on FAT partition and adding following line:
>
> dtparam=i2c
>
> This should make boot firmware to enable device nodes in the device
> tree blob during the boot.
Thanks a lot! I can confirm that this makes i2c "work" on Zero with
12-RELEASE (almost) to the extent described above for 11.2-STABLE (it
detects/creates only iic0, not iic1, but as far as I understand from
other sources, iic0 is all that is needed for "plain B" and thus also
for Zero).
Should I file a PR for this? I assume that the i2c nodes being
disabled is not intentional...
--Per Hedeland
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