C100P Tweaks

Pros

• 15 hour battery life for my typical use (ssh, vim, pdfs, music)
• 6 hours for 'worst case' (video playback, max bright, max volume)
• 16 days in suspend
• looks like a midget macbook pro
• totally fanless and silent
• solid aluminum chassis
• lightweight, under 1kg
• lovely IPS screen
• backlight goes high enough to work in sun
• backlight goes low enough to not hurt when reading at night
• screen is usable in full sunlight without backlight
• 2W typical power draw (a 20cm solar panel is plenty)
• decent keyboard
• goofy tablet mode
• flush uSD socket

Cons

Internals

Brian Ditfeld did an excellent C100P teardown and I have to say I like what I see. When the battery finally goes it appears it will be reasonably easy to fit a new li-poly pack in there. Maybe not the full 31Wh of the original, but even half the battery life would still be acceptable in 10 years.

Benchmark-wise, the single-thread performance of the Flip is a bit faster than my old Thinkpad X120e with an E350 CPU. Not going to set any records, but plenty enough for my dev work.

Platform packages to install:

The HW accelerated 3D drivers are what you'd expect from binary drivers. They mostly-sort-of work. The biggest problem I've seen is they fall over in a stiff breeze. For example, Stellarium would run at a buttery smooth 60 FPS for a few minutes and then everything would die. (No overheating though.) Capping the frame rate to 15 FPS has made it stable enough for a good star-viewing session. I expect you will run into similar problems on a per-application basis.

The function keys don't generate XF86events, I bound Control+FX to scripts instead. The only one that I've had trouble with was the "lock" button (keycode 191), which binds to XF86Tools. For some reason my WM would not recognize that so I remapped XF86Battery to it. The dedicated volume buttons work properly.

Screen rotation through xrandr doesn't work at all, limiting the usefulness of tablet mode somewhat. But mupdf is usable enough though you have to drag the page "backwards" to advance in some orientations. While I still think the tablet mode is a little silly, it has lead to a noticeable increase in the number of PDF papers I read. Could also just be the novelty too.

To get the most battery life you need to run the backlight as low as possible. The easiest way to do this is to use a console theme with a white background. White backgrounds are also usable in full sun with the backlight disabled. I find they reduce eyestrain because it forces you to use the minimum contrast ratio. (If you think they are blinding, try turning down the backlight!) Almost all console applications assume a dark background and at some point I need to publish the collection of themes I've been putting together.

I have heard from a trustworthy source that these boards should be able to safely take up to 19V. Be warned that I have not confirmed it, nor do I plan to! The lower voltage cutoff has some hysteresis and is 9.8V (falling) or 10.2V (rising). If you want to experiment with alternative DC power supplies you can splice a barrel jack into the power cable. It is only a simple coaxial cable and there is no third wire for signaling the capacity of the power brick. I've operated the Flip from NiMH AA batteries (plus a boost regulator) and it is almost practical - you burn through an average of one cell per hour.

Scripts and Commands

Little odds and ends. These are designed to be as WM agnostic as possible. Most scripts require xosd and terminus-font installed.

Download the scripts from https://github.com/keenerd/c100p-tweaks/

Controlling the battery charge limits is done between sudoers and bashrc with the charge_current alias and the charge_until function. The charge_current requires the ec-utils package and sets how many milliamps flow into the battery during charging. The default value is 3456 and setting it to 0 will disable battery charging. Other small numbers may be useful for a gentle slow charging or using a smaller DC adapter. For example, reducing the current to 590 milliamps means you could charge the laptop (while off or suspended) from a USB port with a boost converter. The charge_until function takes a number between 0 and 100 and stops charging the battery when that percentage is reached. By never taking the charge over 80% for normal use I hope to greatly extend how many years the non-replaceable battery will last.

Suspend has some minor wonkiness. First, closing the lid will generate a wakeup event. A small delay is needed if you are manually triggering suspend. And then during the wakeup, the touchpad always generates a drag event towards the upper right corner of the screen. I handle both of these with an alias in ~/.bashrc

alias suspend="echo 'Five seconds!'; sleep 5; xinput -disable 'Elan Touchscreen'; sudo systemctl suspend; xinput -enable 'Elan Touchscreen'"

The c100p.auto-suspend.sh script requires a little explanation. I really don't like my computer entering suspend at a bad time. Closed the lid? I don't want to lose my wifi connection. Simple X11 idle time? Maybe I'm not in X. Or I'm compiling a build, downloading updates, etc. So the auto-suspend checks a half a dozen criteria every minute. After several minutes of idleness it blasts a warning across the screen. And one minute after that it finally enters suspend. Note that there is no way to detect idle time on the TTY. To hack around this, adjust your ~/.bashrc with PROMPT_COMMAND="touch /tmp/.bashidle" and the last-modified time of that file will be a proxy for tty idle time. (Obviously this has flaws if you simply stay in one program like emacs instead of your local shell, adjust accordingly.) ZSH requires further hackery for the equivalent.

A bit of background on the c100p.status.sh script; I grew up with floppy-based computers that barely had an operating system, where you could listen closely and hear every single twitch the machine made. And when Windows came around, I was running it on very underspecced systems. So it was natural for me to keep an eye on everything with TinyResMeter. Cleaning up errant processes required constant vigilance. So when I moved to Linux, I immediately put together a sweet Conky setup. But over the years I've realized that Linux was pretty amazing at resource management. I didn't need to be vigilant, the OS was. And then I realized the system monitor might be chewing up 10% of my CPU with the constant updates and graphical shininess. And providing a useless distraction of flickering numbers. The eventual evolution of system monitoring has left me with the status script. It only pops up when I am curious and hit the keybind for it. (On the Flip it's bound to the goofy dedicated lock button.) It is not very efficient code with lots of bash shelling, but it runs so rarely as to hardly matter. On computers with much shorter battery life I usually compliment it with a periodic alarm script that sounds the klaxons when approaching a dangerous status, but I have not felt the need to do that here.

Helpful Hardware Info

Specifically relating to the previously mentioned gaps.

/dev/video2 appears to be the device
1280x720 960x540 640x480    supported resolutions

v4l2-ctl --list-formats -d /dev/video2
ioctl: VIDIOC_ENUM_FMT
    Index       : 0
    Type        : Video Capture
    Pixel Format: 'MJPG' (compressed)
    Name        : MJPEG

    Index       : 1
    Type        : Video Capture
    Pixel Format: 'YUYV'
    Name        : YUV 4:2:2 (YUYV)

Touchscreen: