Real estate value Let s clear this one up first. It s not about real estate value, for most companies. City planners and real estate investors might care, but even if your average company owned their building they d close it in an instant all other things being equal. An unoccupied building costs a lot less to maintain. And plenty of companies rent and would save money even if there s a substantial exit fee.

Occupancy levels That said, once you have anyone in the building the equation changes. If you re having to provide power, heating, internet, security/front desk staff etc, you want to make sure you re getting your money s worth. There s no point heating a building that can seat 100 for only 10 people present. One option is to downsize the building, but that leads to not being able to assign everyone a desk, for example. No one I know likes hot desking. There are also scheduling problems about ensuring there are enough desks for everyone who might turn up on a certain day, and you ve ruled out the option of company/office wide events.

Coexistence builds relationships As a remote worker I wish it wasn t true that most people find it easier to form relationships in person, but it is. Some of this can be worked on with specific teambuilding style events, rather than in office working, but I know plenty of folk who hate those as much as they hate the idea of being in the office. I am lucky in that I work with a bunch of folk who are terminally online, so it s much easier to have those casual conversations even being remote, but I also accept I miss out on some things because I m just not in the office regularly enough. You might not care about this ( I just need to put my head down and code, not talk to people ), but don t discount it as a valid reason why companies might want their workers to be in the office. This often matters even more for folk at the start of their career, where having a bunch of experience folk around to help them learn and figure things out ends up working much better in person (my first job offered to let me go mostly remote when I moved to Norwich, but I said no as I knew I wasn t ready for it yet).

Coexistence allows for unexpected interactions People hate the phrase water cooler chat , and I get that, but it covers the idea of casual conversations that just won t happen the same way when people are remote. I experienced this while running Black Cat; every time Simon and I met up in person we had a bunch of useful conversations even though we were on IRC together normally, and had a VoIP setup that meant we regularly talked too. Equally when I was at Nebulon there were conversations I overheard in the office where I was able to correct a misconception or provide extra context. Some of this can be replicated with the right online chat culture, but I ve found many places end up with folk taking conversations to DMs, or they happen in private channels. It happens more naturally in an office environment.

It s easier for bad managers to manage bad performers Again, this falls into the category of things that shouldn t be true, but are. Remote working has increased the ability for people who want to slack off to do so without being easily detected. Ideally what you want is that these folk, if they fail to perform, are then performance managed out of the organisation. That s hard though, there are (rightly) a bunch of rights workers have (I m writing from a UK perspective) around the procedure that needs to be followed. Managers need organisational support in this to make sure they get it right (and folk are given a chance to improve), which is often lacking.

Summary Look, I get there are strong reasons why offering remote is a great thing from the company perspective, but what I ve tried to outline here is that a return-to-office mandate can have some compelling reasons behind it too. Some of those might be things that wouldn t exist in an ideal world, but unfortunately fixing them is a bigger issue than just changing where folk work from. Not acknowledging that just makes any reaction against office work seem ill-informed, to me.

Rust First I want to talk about Rust, which is the language I chose to use for the problems. I ve dabbled a little in it, but I d like more familiarity with the basic language, and some programming problems seemed like a good way to get that. It s a language I want to like; I ve spent a lot of my career writing C, do more in Go these days, and generally think Rust promises a low level, run-time light environment like C but with the rough edges taken off. I set myself the challenge of using just bare Rust; no external crates, no use of cargo. I was accused of playing on hard mode by doing this, but it really wasn t the intention - I figured that I should be able to do what I needed without recourse to anything outside the core language, and didn t want what seemed like the extra complexity of dealing with cargo. That caused problems, however. I m used to by-default generic error handling in Go through the error type, but Rust seems to have much more tightly typed errors. I was pointed at anyhow as the right way to do this in Rust. I still find this surprising; I ended up using unwrap() a lot when I think with more generic error handling I could have used ?. The other thing I discovered is that by default rustc is heavy on the debug output. I got significantly better results on some of the solutions with rustc -O -C target-cpu=native source.rs. I probably shouldn t be surprised by this, but worth noting. Rust, to me, has a syntax only a C++ programmer could love. I am not a C++ programmer. Coming from C I found Go to be a nice, simple syntax to learn. Rust has not been the same. There s a lot more punctuation, and it s not always clear to me what it s doing. This applies more when reading other people s code than when writing it myself, obviously, but I see a lot of Rust code that could give Perl a run for its money in terms of looking like line noise. The borrow checker didn t bug me too much, but did add overhead to my thinking. The Rust compiler is generally very good at outputting helpful error messages when the programmer is an idiot. I ended up having to use a RefCell for one solution, and using .iter() for loops rather than explicit iterators (why, why is this different?). I also kept forgetting to explicitly mark variables as mutable when declaring them. Things I liked? There s a rich set of first class data types. Look, I m a C programmer, I m easily pleased. You give me some sort of hash array and I ll be happy. Rust manages that, tuples, strings, all the standard bits any modern language can provide. The whole impl thing for adding methods to structures I like as a way of providing some abstraction, though I think Go has a nicer syntax for it. The compiler, as mentioned, is great at spitting out useful errors for the most part. Also although I wasn t using external crates for AoC I do appreciate there s a decent ecosystem there now (though that brings up another gripe: rust seems to still be a fairly fast moving target, to the extent I can no longer rely on the compiler in Debian stable to be able to compile random projects I find).

Advent of Code Let s talk about the advent of code bit now. Hopefully it s long enough since it came out that this won t be spoilers for anyone, but if you haven t attempted the 2023 AoC and might, you might want to stop reading here. First, a refresher on the format for those who might not be aware of it. Problems are posted daily from December 1st until the 25th. Each is in 2 parts; the second part is not viewable until you have provided the correct answer for the first part. There s a whole leaderboard thing going on, but the puzzle opens at midnight UTC-5 so generally by the time I wake up and have time to look the problem has been solved many times over; no chance of getting listed. Credit to AoC creator, Eric Wastl, for writing up the set of problems in an entertaining fashion. I quite enjoyed seeing how the puzzle would be phrased each day, and the whole thing obviously brings a lot of joy to folk I know. I always start AoC thinking it ll be a fun set of puzzles to solve. Then something happens and I miss a day or two, and all of a sudden I ve a bunch of catching up to do and it s all a bit more of a chore. I hit that at some points this time, but made a concerted effort to try and power through it. That perseverance was required up front, because I found the second part of Day 1 to be ill specified, and had to iterate a few times to actually calculate the desired solution (IIRC, issues about whether sevenone at the end of a line ended up as 7 or 1 really tripped me up). I don t recall any other problems that bit me as hard on the specification as this one, but it happening up front was unfortunate. The short example input doesn t always help with this either; either it s not enough to be able to extrapolate patterns, or it doesn t show all the variations you need to account for (that aren t fully specified in the text), or in a few cases it turned out I needed to understand the shape of the actual data to produce a solution that could actually complete in a reasonable time. Which brings me to another matter, sometimes brute force doesn t actually work. This is fine, but the second part of the day s problem can change the approach you d take. So sometimes I got lucky in the way I handled the first half, and doing the second half was a simple 5 minute tweak, and sometimes I had to entirely change the way I was storing data. You might claim that if I was a better programmer I d have always produced a first half solution that was amenable to extension for the second half. First, I dispute that; I think there are always situations where the problem domain can change in enough directions that you can t handle all of them without a lot of effort. Secondly, I didn t find AoC an environment that encouraged me to optimise for generic solutions. Maybe some of the puzzles in isolation would allow for that, but a month of daily problems to solve while still engaging in regular life meant I hacked things up, took short cuts based on the knowledge I had of the input data, etc, etc. Overall I can see the appeal, but the sheer quantity and the fact I write code as part of my day job just made it feel too much like a chore, rather than a fun mental exercise. I did wonder how they d look as a set of interview puzzles (obviously a subset, rather than all of them), but I m not sure how you d actually use them for that - I wouldn t want anyone to have to solve them in a live interview. So, in case it s not obvious, I m not planning to engage in AoC again this yet. But I m continuing to persevere with Rust (though most of my work stuff is thankfully still Go).

• It to be fairly lightweight, so I can run it on a laptop while usefully doing other things
• I need a TPM 2.0 device to appear to the guest OS, but it doesn t need to be a real TPM
• Block device discard should work, so I can back it with a qcow2 image and use fstrim to keep the actual on disk size small, without constraining my potential for file system expansion should I need it
• I ve no need for graphics, in fact a serial console would be better as it eases copy & paste, especially when I screw up kernel changes

#!/bin/sh
BASEDIR=/home/noodles/debian-qemu
if [ ! -S $ BASEDIR /swtpm/swtpm-sock ]; then
    echo Starting swtpm:
    swtpm socket --tpmstate dir=$ BASEDIR /swtpm \
        --tpm2 \
        --ctrl type=unixio,path=$ BASEDIR /swtpm/swtpm-sock &
fi
echo Starting QEMU:
qemu-system-x86_64 -enable-kvm -m 2048 \
    -machine type=q35 \
    -smbios type=1,serial=N00DL35,uuid=fd225315-f72a-4d66-9b16-55363c6c938b \
    -drive if=pflash,format=qcow2,readonly=on,file=/usr/share/edk2/ovmf/OVMF_CODE_4M.qcow2 \
    -drive if=pflash,format=raw,file=$ BASEDIR /OVMF_VARS.fd \
    -global isa-debugcon.iobase=0x402 -debugcon file:$ BASEDIR /debian.ovmf.log \
    -device virtio-blk-pci,drive=drive0,id=virblk0 \
    -drive file=$ BASEDIR /debian-12-efi.qcow2,if=none,id=drive0,discard=on \
    -net nic,model=virtio -net user \
    -chardev socket,id=chrtpm,path=$ BASEDIR /swtpm/swtpm-sock \
    -tpmdev emulator,id=tpm0,chardev=chrtpm \
    -device tpm-tis,tpmdev=tpm0 \
    -display none \
    -nographic \
    -boot menu=on

Conferences The only Free Software related conference I made it to this year was DebConf23 in Kochi, India. Changes with projects at work meant I couldn t justify anything work related. This year I m planning to make it to FOSDEM, and haven t made a decision on DebConf24 yet.

Debian Most of my contributions to Free software continue to happen within Debian. I started the year working on retrogaming with Kodi on Debian. I got this to a much better state for bookworm, with it being possible to run the bsnes-mercury emulator under Kodi using RetroArch. There are a few other libretro backends available for RetroArch, but Kodi needs some extra controller mappings packaged up first. Plenty of uploads were involved, though some of this was aligning all the dependencies and generally cleaning things up in iterations.

• retroarch: 1.13.0-dfsg+3, 1.14.0+dfsg-1, 1.15.0+dfsg-1, 1.16.0.3+dfgs-1
• libretro-core-info uploads: 1.14.0-1, 1.15.0-1.
• libretro-bsnes-mercury: 094+git20220807-2, 094+git20220807-3, 094+git20220807-4, 094+git20220807-5, 094+git20220807-6, 094+git20220807-7, 094+git20220807-8.
• kodi-game-libretro: 20.2.0-2, 20.2.2-1, 20.2.2-2, 20.2.4-1, 20.2.4-2
• rcheevos: 10.5.0-2, 10.6.0-1, 10.7.0-1, 10.7.1-1.

I continued to work on a few packages within the Debian Electronics Packaging Team. OpenOCD produced a new release in time for the bookworm release, so I uploaded 0.12.0-1. There were a few minor sigrok cleanups - sigrok 0.3, libsigrokdecode 0.5.3-4 + libsigrok 0.5.2-4 / 0.5.2-5. While I didn t manage to get the work completed I did some renaming of the ESP8266 related packages - gcc-xtensa-lx106 (which saw a 13 upload pre-bookworm) has become gcc-xtensa (with 14) and binutils-xtensa-lx106 has become binutils-xtensa (with 6). Binary packages remain the same, but this is intended to allow for the generation of ESP32 compiler toolchains from the same source. onak saw 0.6.3-1 uploaded to match the upstream release. I also uploaded libgpg-error 1.47-1 (though I can claim no credit for any of the work in preparing the package) to help move things forward on updating gnupg2 in Debian. I NMUed tpm2-pkcs11 1.9.0-0.1 to fix some minor issues pre-bookworm release; I use this package myself to store my SSH key within my laptop TPM, so I care about it being in a decent state. sg3-utils also saw a bit of love with 1.46-2 + 1.46-3 - I don t work in the storage space these days, but I m still listed as an uploaded and there was an RC bug around the library package naming that I was qualified to fix and test pre-bookworm. Related to my retroarch work I sponsored uploads of mgba for Ryan Tandy: 0.10.0+dfsg-1, 0.10.0+dfsg-2, 0.10.1+dfsg-1, 0.10.2+dfsg-1, mgba 0.10.1+dfsg-1+deb12u1. As part of the Data Protection Team I responded to various inbound queries to that team, both from project members and those external to the project. I continue to keep an eye on Debian New Members, even though I m mostly inactive as an application manager - we generally seem to have enough available recently. Mostly my involvement is via Front Desk activities, helping out with queries to the team alias, and contributing to internal discussions as well as our panel at DebConf23. Finally the 3 month rotation for Debian Keyring continues to operate smoothly. I dealt with 2023.03.24, 2023.06.26, 2023.06.29, 2023.09.10, 2023.09.24 + 2023.12.24.

Linux I had a few minor patches accepted to the kernel this year. A pair of safexcel cleanups (improved error logging for firmware load fail and cleanup on load failure) came out of upgrading the kernel running on my RB5009. The rest were related to my work on repurposing my C.H.I.P.. The AXP209 driver needed extended to support GPIO3 (with associated DT schema update). That allowed Bluetooth to be enabled. Adding the AXP209 internal temperature ADC as an iio-hwmon node means it can be tracked using the normal sensor monitoring framework. And finally I added the pinmux settings for mmc2, which I use to support an external microSD slot on my C.H.I.P.

Personal projects 2023 saw another minor release of onak, 0.6.3, which resulted in a corresponding Debian upload (0.6.3-1). It has a couple of bug fixes (including a particularly annoying, if minor, one around systemd socket activation that felt very satisfying to get to the bottom of), but I still lack the time to do any of the major changes I would like to. I wrote listadmin3 to allow easy manipulation of moderation queues for Mailman3. It s basic, but it s drastically improved my timeliness on dealing with held messages.

Work related This year only involved a single upstream related submission; a fix for tpm_tis interrupts with the Lenovo P620 that then got dropped when the change that caused the issue was reverted. That wraps up 2023. I ve got no particular goals for this year; looking around my desk I ve a few ARM based devices I d like to get running a mainline kernel. I need to play about a bit more with the retroarch bits (if I really had time I d do the migration for Kodi to PCRE2, as that s currently causing testing migration issues), perhaps getting some more controller mappings packaged. But no promises.

0.6.3 - 26th September 2023

• Fix systemd detection + socket activation
• Add CMake checking for Berkeley DB
• Minor improvements to keyd logging
• Fix decoding of signature creation time
• Relax version check on parsing signature + key packets
• Improve HTML escaping
• Handle failed database initialisation more gracefully
• Fix bug with EDDSA signatures with top 8+ bits unset

Talks (videos not yet up for all, but should appear for most)

• Opening Ceremony
  Not much to say here; welcome to DebConf!
• Continuous Key-Signing Party introduction
  I ended up running this, as Gunnar couldn t make it. Debian makes heavy use of the OpenPGP web of trust (no mass ability to send out Yubikeys + perform appropriate levels of identity verification), so making sure we re appropriately cross-signed, and linked to local conference organisers, is a dull but important part of the conference. We use a modified keysigning approach where identity verification + fingerprint confirmation happens over the course of the conference, so this session was just to explain how that works and confirm we were all working from the same fingerprint list.
• State of Stateless - A Talk about Immutability and Reproducibility in Debian
  Stateless OSes seem to be gaining popularity, so I went along to this to see if there was anything of note. It was interesting, but nothing earth shattering - very high level.
• What s missing so that Debian is finally reproducible?
  Reproducible builds are something I ve been keeping an eye on for a long time, and I continue to be impressed by the work folks are putting into this - both for Debian, and other projects. From a security standpoint reproducible builds provide confidence against trojaned builds, and from a developer standpoint knowing you can build reproducibly helps with not having to keep a whole bunch of binary artefacts around.
• Hello from keyring-maint
  In the distant past the process of getting your OpenPGP key into the Debian keyring (which is used to authenticate uploads + votes, amongst other things) was a clunky process that was often stalled. This hasn t been the case for at least the past 10 years, but there s still a residual piece of project memory that thinks keyring is a blocker. So as a team we say hi and talk about the fact we do monthly updates and generally are fairly responsive these days.
• A declarative approach to Linux networking with Netplan
  Debian s /etc/network/interfaces is a fairly basic (if powerful) mechanism for configuring network interfaces. NetworkManager is a better bet for dynamic hosts (i.e. clients), and systemd-network seems to be a good choice for servers (I m gradually moving machines over to it). Netplan tries to provide a unified mechanism for configuring both with a single configuration language. A noble aim, but I don t see a lot of benefit for anything I use - my NetworkManager hosts are highly dynamic (so no need to push shared config) and systemd-network (or /etc/network/interfaces) works just fine on the other hosts. I m told Netplan has more use with more complicated setups, e.g. when OpenVSwitch is involved.
• Quick peek at ZFS, A too good to be true file system and volume manager.
  People who use ZFS rave about it. I m naturally suspicious of any file system that doesn t come as part of my mainline kernel. But, as a longtime cautious mdraid+lvm+ext4 user I appreciate that there have been advances in the file system space that maybe I should look at, and I ve been trying out btrfs on more machines over the past couple of years. I can t deny ZFS has a bunch of interesting features, but nothing I need/want that I can t get from an mdraid+lvm+btrfs stack (in particular data checksumming + reflinks for dedupe were strong reasons to move to btrfs over ext4).
• Bits from the DPL
  Exactly what it says on the tin; some bits from the DPL.
• Adulting
  Enrico is always worth hearing talk; Adulting was no exception. Main takeaway is that we need to avoid trying to run the project on martyrs and instead make sure we build a sustainable project. I ve been trying really hard to accept I just don t have time to take on additional responsibilities, no matter how interesting or relevant they might seem, so this resonated.
• My life in git, after subversion, after CVS.
  Putting all of your home directory in revision control. I ve never made this leap; I ve got some Ansible playbooks that push out my core pieces of configuration, which is held in git, but I don t actually check this out directly on hosts I have accounts on. Interesting, but not for me.
• EU Legislation BoF - Cyber Resilience Act, Product Liability Directive and CSAM Regulation
  The CRA seems to be a piece of ill informed legislation that I m going to have to find time to read properly. Discussion was a bit more alarmist than I personally feel is warranted, but it was a short session, had a bunch of folk in it, and even when I removed my mask it was hard to make myself understood.
• What s new in the Linux kernel (and what s missing in Debian)
  An update from Ben about new kernel features. I m paying less attention to such things these days, so nice to get a quick overview of it all.
• Intro to SecureDrop, a sort-of Linux distro
  Actually based on Ubuntu, but lots of overlap with Debian as a result, and highly customised anyway. Notable, to me, for using OpenPGP as some of the backend crypto support. I managed to talk to Kunal separately about some of the pain points around that, which was an interesting discussion - they re trying to move from GnuPG to Sequoia, primarily because of the much easier integration and lack of requirement for the more complicated GnuPG features that sometimes get in the way.
• The Docker(.io) ecosystem in Debian
  I hate Docker. I m sure it s fine if you accept it wants to take over the host machine entirely, but when I ve played around with it that s not been the case. This talk was more about the difficulty of trying to keep a fast moving upstream with lots of external dependencies properly up to date in a stable release. Vendoring the deps and trying to get a stable release exception seems like the least bad solution, but it s a problem that affects a growing number of projects.
• Chiselled containers
  This was kinda of interesting, but I think I missed the piece about why more granular packaging wasn t an option. The premise is you can take an existing .deb and chisel it into smaller components, which then helps separate out dependencies rather than pulling in as much as the original .deb would. This was touted as being useful, in particular, for building targeted containers. Definitely appealing over custom built userspaces for containers, but in an ideal world I think we d want the information in the main packaging and it becomes a lot of work.
• Debian Contributors shake-up
  Debian Contributors is a great site for massaging your ego around contributions to Debian; it s also a useful point of reference from a data protection viewpoint in terms of information the project holds about contributors - everything is already public, but the Contributors website provides folk with an easy way to find their own information (with various configurable options about whether that s made public or not). T ssia is working on improving the various data feeds into the site, but realistically this is the responsibility of every Debian service owner.
• New Member BOF
  I m part of the teams that help get new folk into Debian - primarily as a member of the New Member Front Desk, but also as a mostly inactive Application Manager. It s been a while since we did one of these sessions so the Front Desk/Debian Account Managers that were present did a panel session. Nothing earth shattering came out of it; like keyring-maint this is a team that has historically had problems, but is currently running smoothly.

Storage The main issue with the C.H.I.P. is that it uses MLC NAND, in particular mine has an 8MB H27QCG8T2E5R. That ended up unsupported in Linux, with the UBIFS folk disallowing operation on MLC devices. There s been subsequent work to enable an SLC emulation mode which makes the device more reliable at the cost of losing capacity by pairing up writes/reads in cells (AFAICT). Some of this hit for the H27UCG8T2ETR in 5.16 kernels, but I definitely did some experimentation with 5.17 without having much success. I should maybe go back and try again, but I ended up going a different route. It turned out that BytePorter had documented how to add a microSD slot to the NTC C.H.I.P., using just a microSD to full SD card adapter. Every microSD card I buy seems to come with one of these, so I had plenty lying around to test with. I started with ensuring the kernel could see it ok (by modifying the device tree), but once that was all confirmed I went further and built a more modern u-boot that talked to the SD card, and defaulted to booting off it. That meant no more relying on the internal NAND at all! I do see some flakiness with the SD card, which is possibly down to the dodgy way it s hooked up (I should probably do a basic PCB layout with JLCPCB instead). That s mostly been mitigated by forcing it into 1-bit mode instead of 4-bit mode (I tried lowering the frequency too, but that didn t make a difference). The problem manifests as:

sunxi-mmc 1c11000.mmc: data error, sending stop command

and then all storage access freezing (existing logins still work, if the program you re trying to run is in cache). I can t find a conclusive software solution to this; I m pretty sure it s the hardware, but I don t understand why the recovery doesn t generally work.

Random power offs After I had storage working I d see random hangs or power offs. It wasn t quite clear what was going on. So I started trying to work out how to find out the CPU temperature, in case it was overheating. It turns out the temperature sensor on the R8 is part of the touchscreen driver, and I d taken my usual approach of turning off all the drivers I didn t think I d need. Enabling it (CONFIG_TOUCHSCREEN_SUN4I) gave temperature readings and seemed to help somewhat with stability, though not completely. Next I ended up looking at the AXP209 PMIC. There were various scripts still installed (I d started out with the NTC Debian install and slowly upgraded it to bullseye while stripping away the obvious pieces I didn t need) and a start-up script called enable-no-limit. This turned out to not be running (some sort of expectation of i2c-dev being loaded and another failing check), but looking at the script and the data sheet revealed the issue. The AXP209 can cope with 3 power sources; an external DC source, a Li-battery, and finally a USB port. I was powering my board via the USB port, using a charger rated for 2A. It turns out that the AXP209 defaults to limiting USB current to 900mA, and that with wifi active and the CPU busy the C.H.I.P. can rise above that. At which point the AXP shuts everything down. Armed with that info I was able to understand what the power scripts were doing and which bit I needed - i2cset -f -y 0 0x34 0x30 0x03 to set no limit and disable the auto-power off. Additionally I also discovered that the AXP209 had a built in temperature sensor as well, so I added support for that via iio-hwmon.

WiFi WiFi on the C.H.I.P. is provided by an RTL8723BS SDIO attached device. It s terrible (and not just here, I had an x86 based device with one where it also sucked). Thankfully there s a driver in staging in the kernel these days, but I ve still found it can fall out with my house setup, end up connecting to a further away AP which then results in lots of retries, dropped frames and CPU consumption. Nailing it to the AP on the other side of the wall from where it is helps. I haven t done any serious testing with the Bluetooth other than checking it s detected and can scan ok.

Patches I patched u-boot v2022.01 (which shows you how long ago I was trying this out) with the following to enable boot from external SD:

u-boot C.H.I.P. external SD patch

diff --git a/arch/arm/dts/sun5i-r8-chip.dts b/arch/arm/dts/sun5i-r8-chip.dts
index 879a4b0f3b..1cb3a754d6 100644
--- a/arch/arm/dts/sun5i-r8-chip.dts
+++ b/arch/arm/dts/sun5i-r8-chip.dts
@@ -84,6 +84,13 @@
 		reset-gpios = <&pio 2 19 GPIO_ACTIVE_LOW>; /* PC19 */
 	 ;
 
+	mmc2_pins_e: mmc2@0  
+		pins = "PE4", "PE5", "PE6", "PE7", "PE8", "PE9";
+		function = "mmc2";
+		drive-strength = <30>;
+		bias-pull-up;
+	 ;
+
 	onewire  
 		compatible = "w1-gpio";
 		gpios = <&pio 3 2 GPIO_ACTIVE_HIGH>; /* PD2 */
@@ -175,6 +182,16 @@
 	status = "okay";
  ;
 
+&mmc2  
+	pinctrl-names = "default";
+	pinctrl-0 = <&mmc2_pins_e>;
+	vmmc-supply = <&reg_vcc3v3>;
+	vqmmc-supply = <&reg_vcc3v3>;
+	bus-width = <4>;
+	broken-cd;
+	status = "okay";
+ ;
+
 &ohci0  
 	status = "okay";
  ;
diff --git a/arch/arm/include/asm/arch-sunxi/gpio.h b/arch/arm/include/asm/arch-sunxi/gpio.h
index f3ab1aea0e..c0dfd85a6c 100644
--- a/arch/arm/include/asm/arch-sunxi/gpio.h
+++ b/arch/arm/include/asm/arch-sunxi/gpio.h
@@ -167,6 +167,7 @@ enum sunxi_gpio_number  
 
 #define SUN8I_GPE_TWI2		3
 #define SUN50I_GPE_TWI2		3
+#define SUNXI_GPE_SDC2		4
 
 #define SUNXI_GPF_SDC0		2
 #define SUNXI_GPF_UART0		4
diff --git a/board/sunxi/board.c b/board/sunxi/board.c
index fdbcd40269..f538cb7e20 100644
--- a/board/sunxi/board.c
+++ b/board/sunxi/board.c
@@ -433,9 +433,9 @@ static void mmc_pinmux_setup(int sdc)
 			sunxi_gpio_set_drv(pin, 2);
 		 
 #elif defined(CONFIG_MACH_SUN5I)
-		/* SDC2: PC6-PC15 */
-		for (pin = SUNXI_GPC(6); pin <= SUNXI_GPC(15); pin++)  
-			sunxi_gpio_set_cfgpin(pin, SUNXI_GPC_SDC2);
+		/* SDC2: PE4-PE9 */
+		for (pin = SUNXI_GPE(4); pin <= SUNXI_GPE(9); pin++)  
+			sunxi_gpio_set_cfgpin(pin, SUNXI_GPE_SDC2);
 			sunxi_gpio_set_pull(pin, SUNXI_GPIO_PULL_UP);
 			sunxi_gpio_set_drv(pin, 2);
 		 

I ve sent some patches for the kernel device tree upstream - there s an outstanding issue with the Bluetooth wake GPIO causing the serial port not to probe(!) that I need to resolve before sending a v2, but what s there works for me. The only remaining piece is patch to enable the external SD for Linux; I don t think it s appropriate to send upstream but it s fairly basic. This limits the bus to 1 bit rather than the 4 bits it s capable of, as mentioned above.

Linux C.H.I.P. external SD DTS patch diff diff --git a/arch/arm/boot/dts/sun5i-r8-chip.dts b/arch/arm/boot/dts/sun5i-r8-chip.dts index fd37bd1f3920..2b5aa4952620 100644 --- a/arch/arm/boot/dts/sun5i-r8-chip.dts +++ b/arch/arm/boot/dts/sun5i-r8-chip.dts @@ -163,6 +163,17 @@ &mmc0 status = "okay"; ; +&mmc2 + pinctrl-names = "default"; + pinctrl-0 = <&mmc2_4bit_pe_pins>; + vmmc-supply = <&reg_vcc3v3>; + vqmmc-supply = <&reg_vcc3v3>; + bus-width = <1>; + non-removable; + disable-wp; + status = "okay"; + ; + &ohci0 status = "okay"; ;

As for what I m doing with it, I think that ll have to be a separate post.