Date: Sat, 5 Jan 2019 15:47:50 -0800 From: "Michael Mitchell (megabyte)" <mmitchel@gmail.com> To: Per Hedeland <per@hedeland.org> Cc: Emmanuel Vadot <manu@bidouilliste.com>, freebsd-arm@freebsd.org Subject: Re: i2c on RPi Zero? Message-ID: <4C1DFE20-8124-47EB-995C-F1029C1FA4DA@gmail.com> In-Reply-To: <d846cf54-6550-6ab6-58fd-3324f2df6543@hedeland.org> References: <229e0d36-a07b-8551-9613-0bf5748352e7@hedeland.org> <dc9441e2-9858-989e-a135-3ae37de0925b@hedeland.org> <20190105195808.GA53872@bluezbox.com> <e981729d-bb71-c74e-aaa7-86c7447b1f24@hedeland.org> <20190105215608.GA55315@bluezbox.com> <20190105230306.2ad9d0ba2c2df0e8fac5f053@bidouilliste.com> <d846cf54-6550-6ab6-58fd-3324f2df6543@hedeland.org>
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simplified: why would freebsd demand a different device tree than what you get when you download it from raspberrypi.org = <http://raspberrypi.org/>? all the internet documentation describes how to manipulate the device tree. we are at their mercy for the boot up folder as it is... mdm > On Jan 5, 2019, at 3:39 PM, Per Hedeland <per@hedeland.org> wrote: >=20 > On 2019-01-05 23:03, Emmanuel Vadot wrote: >> On Sat, 5 Jan 2019 13:56:08 -0800 >> Oleksandr Tymoshenko <gonzo@bluezbox.com> wrote: >>> Per Hedeland (per@hedeland.org) wrote: >>>> 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: >>>>>>=20 >>>>>> FreeBSD-12.0-STABLE-arm-armv6-RPI-B-20190103-r342709.img - still = no >>>>>> luck. >>>>>>=20 >>>>>> 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".) >>>>>>=20 >>>>>> 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. >>>>>>=20 >>>>>> (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.) >>>>>=20 >>>>> 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: >>>>>=20 >>>>> dtparam=3Di2c >>>>>=20 >>>>> This should make boot firmware to enable device nodes in the = device >>>>> tree blob during the boot. >>>>=20 >>>> 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). >>>>=20 >>>> Should I file a PR for this? I assume that the i2c nodes being >>>> disabled is not intentional... >>>=20 >>> Yes, please do. There are also other devices, that should be enabled = by >>> default, like SPI. >> Why should we enabled them by default ? >> We have no correct way for switching a pin to gpio mode (you can do >> that with gpioctl on some system but I consider it as a bug) so if I >> want to use the i2c/spi/whatever pins as gpio and the default image = set >> it to another function I'm stuck. >> Using the rpi fundation dtb means that every settings that they set >> for Linux will also be set for us, so every tutorial on the web where >> people saying that you should set something in config.txt will apply = to >> FreeBSD too. >> The current settings aren't a bug, it's a feature (c). >=20 > OK... - so your take seems to be that FreeBSD users should google for > the "Linux way" to (e.g.) enable i2c on RPi. I googled "enable i2c on > raspberry pi" now, and indeed it brought up lots of Linux stuff, but > unfortunately it mostly says to run 'raspi-config', which I can't find > on my FreeBSD installation (and didn't actually expect to, of course). >=20 > If I explicitly add "config.txt" to the search string, I do indeed > find some info about what to put in that file - but of course I > wouldn't have done that if I didn't already know that this was the > file that needed to be edited... >=20 > I'm all for using "standard" components (even when "standard" means > "Linux"), and reducing the amount of FreeBSD-specific work that you > and others need to put in to support FreeBSD on these "odd" systems - > and as a long time (Free)BSD user, I actually prefer to edit a file > over running some GUI tool without knowing what it does. >=20 > But I really think there needs to be a bit more help directed > specifically at the FreeBSD user here (if there is and I just haven't > found it, please enlighten me). A few words (besides "configuration > for start.elf":-) about what config.txt is good for, and perhaps a > pointer to e.g. > https://www.raspberrypi.org/documentation/configuration/device-tree.md > (found it from your hints, thanks!), on the > https://wiki.freebsd.org/FreeBSD/arm/Raspberry%20Pi page may be > enough. >=20 > And despite the whining above, I really do appreciate all your efforts > to make it possible to run FreeBSD on these systems - many thanks! >=20 > --Per Hedeland > _______________________________________________ > freebsd-arm@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-arm > To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org"
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