More Bluetooth (and gaming) features

In the midst of post-release bug fixing, we've also added a fair number of new features to our stack. As usual, new features span a number of different components, so integrators will have to be careful picking up all the components when, well, integrating.

PS3 clones joypads support

Do you have a PlayStation 3 joypad that feels just a little bit "off"? You can't find the Sony logo anywhere on it? The figures on the face buttons look like barbed wire? And if it were a YouTube video, it would say "No copyright intended"?

Bingo. When plugged in via USB, those devices advertise themselves as SHANWAN or Gasia, and implement the bare minimum to work when plugged into a PlayStation 3 console. But as a Linux computer would behave slightly differently, we need to fix a couple of things.

The first fix was simple, but necessary to be able to do any work: disable the rumble motor that starts as soon as you plug the pad through USB.

Once that's done, we could work around the fact that the device isn't Bluetooth compliant, and hard-code the HID service it's supposed to offer.

Bluetooth LE Battery reporting

Bluetooth Low Energy is the new-fangled (7-year old) protocol for low throughput devices, from a single coin-cell powered sensor, to input devices. What's great is that there's finally a standardised way for devices to export their battery statuses. I've added support for this in BlueZ, which UPower then picks up for desktop integration goodness.

There are a number of Bluetooth LE joypads available for pickup, including a few that should be firmware upgradeable. Look for "Bluetooth 4" as well as "Bluetooth LE" when doing your holiday shopping.

gnome-bluetooth work

Finally, this is the boring part. Benjamin and I reworked code that's internal to gnome-bluetooth, as used in the Settings panel as well as the Shell, to make it use modern facilities like GDBusObjectManager. The overall effect of this is, less code, less brittle and more reactive when Bluetooth adapters come and go, such as when using airplane mode.

Apart from the kernel patch mentioned above (you'll know if you need it :), those features have been integrated in UPower 0.99.7 and in the upcoming BlueZ 5.48. And they will of course be available in Fedora, both in rawhide and as updates to Fedora 27 as soon as the releases have been done and built.

GG!

Gadget reviews

Not that I'm really running after more gadgets, but sometimes, there is a need that could only be soothed through new hardware.

Bluetooth UE roll

Got this for my wife, to play music when staying out on the quays of the Rhône, playing music in the kitchen (from a phone or computer), or when she's at the photo lab.

It works well with iOS, MacOS X and Linux. It's very easy to use, with whether it's paired, connected completely obvious, and the charging doesn't need specific cables (USB!).

I'll need to borrow it to add battery reporting for those devices though. You can find a full review on Ars Technica.

Sugru (!)

Not a gadget per se, but I bought some, used it to fix up a bunch of cables, repair some knickknacks, and do some DIY. Highly recommended, especially given the current price of their starter packs.

15-pin to USB Joystick adapter

It's apparently from Ckeyin, but you'll find the exact same box from other vendors. Made my old Gravis joystick work, in the hope that I can make it work with DOSBox and my 20-year old copy of X-Wing vs. Tie Fighter.

Microsoft Surface ARC Mouse

That one was given to me, for testing, works well with Linux. Again, we'll need to do some work to report the battery. I only ever use it when travelling, as the batteries last for absolute ages.

Logitech K750 keyboard

Bought this nearly two years ago, and this is one of my best buys. My desk is close to a window, so it's wireless but I never need to change the batteries or think about charging it. GNOME also supports showing the battery status in the Power panel.

Logitech T650 touchpad

Got this one in sale (17€), to replace my Logitech trackball (one of its buttons broke...). It works great, and can even get you shell gestures when run in Wayland. I'm certainly happy to have one less cable running across my desk, and reuses the same dongle as the keyboard above.

If you use more than one devices, you might be interested in this bug to make it easier to support multiple Logitech "Unifying" devices.

ClicLite charger

Got this from a design shop in Berlin. It should probably have been cheaper than what I paid for it, but it's certainly pretty useful. Charges up my phone by about 20%, it's small, and charges up at the same time as my keyboard (above).

Dell S2340T

Bought about 2 years ago, to replace the monitor I had in an all-in-one (Lenovo all-in-ones, never buy that junk).

Nowadays, the resolution would probably be considered a bit on the low side, and the touchscreen mesh would show for hardcore photography work. It's good enough for videos though and the speaker reaches my sitting position.

It's only been possible to use the USB cable for graphics for a couple of months, and it's probably not what you want to lower CPU usage on your machine, but it works for Fedora with this RPM I made. Talk to me if you can help get it into RPMFusion.

Shame about the huge power brick, but a little bonus for the builtin Ethernet adapter.

Surface 3

This is probably the biggest ticket item. Again, I didn't pay full price for it, thanks to coupons, rewards, and all. The work to getting Linux and GNOME to play well with it is still ongoing, and rather slow.

I won't comment too much on Windows either, but rather as what it should be like once Linux runs on it.

I really enjoy the industrial design, maybe even the slanted edges, but one as to wonder why they made the USB power adapter not sit flush with the edge when plugged in.

I've used it a couple of times (under Windows, sigh) to read Pocket as I do on my iPad 1 (yes, the first one), or stream videos to the TV using Flash, without the tablet getting hot, or too slow either. I also like the fact that there's a real USB(-A) port that's separate from the charging port. The micro SD card port is nicely placed under the kickstand, hard enough to reach to avoid it escaping the tablet when lugged around.

The keyboard, given the thickness of it, and the constraints of using it as a cover, is good enough for light use, when travelling for example, and the layout isn't as awful as on, say, a Thinkpad Carbon X1 2nd generation. The touchpad is a bit on the small side though it would have been hard to make it any bigger given the cover's dimensions.

I would however recommend getting a Surface Pro if you want things to work right now (or at least soon). The one-before-last version, the Surface Pro 3, is probably a good target.

My GNOME 3.12 in numbers

1 new GNOME Videos, 1 updated Bluetooth panel, 2 new thumbnailers, 9 grilo sources, and 1 major UPower rework.

I'm obviously very attached to the GNOME Videos UI changes, the first major UI rework in its 12-year existence.

GNOME Videos watching itself

Go read the press release and follow to the release notes.

Reducing wake-ups, the 2013 edition

While doing work on UPower, trying to reduce its wake-ups when idle, I realised that a couple of applications on my desktop were waking up far more than should be necessary.

Detecting wake-ups

First, we need to detect wake-ups. This is a fairly well-known, and old, process, using the venerable PowerTop.

# powertop --html=/tmp/foo.html --time=60

You can increase the number of seconds to get a more realistic view of your machine's idleness, but this is enough to show the main culprits.

In my case, evolution, gnote and devhelp were all waking up about 30 times a second whilst mostly idle. Evolution might be an outlier, as it also talks to the network, and is a bigger application to debug, so I started with devhelp.

$ strace -vvv -p `pidof devhelp`
Process 19069 attached
restart_syscall(<... resuming interrupted call ...>) = 0
recvfrom(6, 0x23fece4, 4096, 0, 0, 0)   = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}, {fd=3, events=POLLIN}], 3, 17) = 0 (Timeout)
recvfrom(6, 0x23fece4, 4096, 0, 0, 0)   = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}, {fd=3, events=POLLIN}], 3, 17) = 0 (Timeout)

And the screen fills up with EAGAIN errors. This looks a lot like a a timeout being called too often.

Debugging wake-ups

I started sprinkling debug in g_main_context_prepare(), the function that prepares the various timeout and idle sources for dispatch, and calculates the timeouts for each poll() operation.

Something like:

if (source_timeout > 0 && source_timeout <= 20)

  g_message ("Source '%s' has very low timeout %d", g_source_get_name (source), source_timeout);

The problem is we end up getting a null source name for almost all of the sources. This is where g_source_set_name() and its sibling g_source_set_name_by_id() come in handy.

timeout_id = g_timeout_add (timeout, myfunction, mydata);

g_source_set_name_by_id (timeout_id, "[module-name] myfunction");

And we start doing that all over GTK+. As you can see from the patches in the bug, there's not just timeouts added by g_timeout_add() that we need to name.

In custody

The huge amount of debug shown when running our application with the gmain.c debug above tells us:

GLib-Message: Source 0x2d4f380 '[gtk+] gdk_frame_clock_paint_idle' has very low timeout 17

even when the window doesn't change, is in the background, and not updating. About 30 times a second.

Who are you gonna call?

Or by whom have you been called, rather. This is a small section of my ~/.gdbinit which will break on a particular function, print a backtrace, and continue. It makes it easier to interact with the logs after the fact, especially if they are calls that happen often and you're not interested in all the calls.

set breakpoint pending on

break gdk_frame_clock_begin_updating

commands

bt

continue

end

We did the same for gdk_frame_clock_begin_updating and found a backtrace similar to the one in Bugzilla. We only needed to start reading some code after that, and figuring out what was going on. The result was a bug in GTK+, likely a regression from GTK+ 3.8.

Your laptop should last a bit longer when the updates hit.

TL;DR

Name your timeouts with g_source_set_name_by_id(), run powertop, and file bugs against broken applications.

Update: Fixed powertop command-line.

More power management changes

As is becoming common, we will have some more power management changes in GNOME 3.12, though those changes will also affect other desktops, whether they use UPower's D-Bus interface, or libupower-glib, the helper library.

The goals of the exercise were simple:

• reduce wake-ups on the daemon and on the client side
• reduce code duplication amongst desktop environments, and even within the same environment (composite battery, anyone?)
• moving some policy actions to a lower level (one could not request hibernation or suspend when multiple users were logged in without interaction and passwords)

All those changes are now in UPower master ready for testing.

Out with the old

The deprecated interfaces for Suspend, Hibernate, etc. are finally removed, after being obsoleted by logind. We've also removed the QoS interface that nobody was using, and the out-dated battery recall support. It's not that batteries don't explode any more, it's that they don't all come from known-bad batches.

In with the new

We have 2 new properties on each of the devices.

WarningLevel which uses daemon-side configurations to tell you whether a device's battery level is low, critically low, or whether we're about to take action on that critical level.

We also have IconName, which replaces some cut'n'pasted code between desktop components. If your desktop environment has many more icons for all types of devices on low battery, for example, you can ignore this property and use the code you always have.

Using those new properties usefully is the new DisplayDevice object. It groups all the batteries and UPSes in the daemon into one, easy to use object that you can use to display a single status icon in your shell chrome. Obviously, if you want to show more devices, the individual batteries and UPSes are still available through the usual means. And it obviously has the 2 new properties mentioned above, so your session daemon can get told when to show notifications for low batteries.

And finally, using that new combined DisplayDevice is the critical battery action policies. As mentioned above, multi-user systems could not hibernate without requiring the user to enter an administrator password, which is less than convenient when your machine is running out of UPS power fast. The configuration for that policy is now in the daemon itself, with sane defaults, and it will hibernate the machine for you.

And to the modernisation

libupower-glib now uses GDBus, even if the daemon doesn't. The daemon however sends PropertiesChanged signals which means that modern D-Bus bindings will automatically get the new values for properties, instead of polling the daemon. The DeviceChanged and Changed signals have thus been removed.

API changes

They are numerous, too many to mention here. I've posted to the device-kit mailing-list with a list of changes that were made, reply there if you have any questions regarding using UPower in your application or session daemons.

Miscellaneous

systemd >= 207 will save your brightness settings across reboots, and the upcoming systemd 209 will have support for saving keyboard backlight across reboots.

I've made attempts at supporting Intel Rapid Start in systemd, but this will actually require kernel changes. Hopefully we should be able to land this by the time GNOME 3.12 is released.

iDevice changes

If like me you jumped the queue of soccer moms, divorced middle-age business men and fanbois on Friday morning, you might have had a new toy to play with this week-end.

The good news

If you use Fedora 13, we fixed up some bugs and you can now mount your iPaid (private joke) on the desktop, and have it show up with a spiffy icon. All the updates are in updates-testing.

upower got the ability to tell you your battery status when plugging in an iDevice, though you'll need gnome-power-manager from master to see it, and even then, it won't show up on a desktop system without a UPS. Still some UI problems to iron out there.

gvfs will now warn you about the device being locked. Again, this change is only on master as it adds new strings.

nautilus-ideviceinfo is nearly ripe for consumption after my wad of bug fixes. I expect the code to move into the GNOME repos soon after the first release.

The bad news

Still no video, music or e-books syncing on the tablet iDevice.

No support yet for the per-app documents syncing. If you have a jailbroken device, you can use iFile to move your documents to the Documents sub-directory of /var/mobile/Applications/application-UUID (make sure to turn on "Application names" in the preferences).