[Community-news] OLPC News (2006-12-30)

[Walter Bender]

1. B2: Electrical and mechanical improvements that will be part of the B2
build include: CAFE ASIC; DCON running at the proper voltage (lower-power
consumption); anti-glare screen; touch-pad fixed; power overcharge and
undercharge fixed; keyboard improved (including the space-bar and enter
key);  new material in bumpers allowing 100cm drop; improved ribbing and
strength in housing; less wobble in the hinge; display tilt improved by 3–5
degrees; and buttons do not get stuck in housing and are easier to press.

2. CAFE: The CAFE ASIC is working! Marvell tested all three
functions—camera, flash, and SD controllers—with their internal diagnostic
software and the ASIC passed basic tests. We also tested CAFE with an AMD
Geode board and regular Linux PC. Basic register read/write, data
read/write, and DMA transfers all passed.

3. Power management: There has been a concerted effort over the last year
toward enabling Linux to stay idle as much of the time as possible to
conserve power. One aspect of this are the “tickless” patches, now going
into mainline Linux, that eliminates a constant “tick” (traditionally
100hz) for process scheduling in favor of doing all scheduling by computing
when next to wake the machine.  Linux has been weak in this area relative
to other systems. Other aspects are fixing user-space applications that may
be doing stupid polling, as pointed out by Dave Jone's “Why user space
sucks” talk at OLS last summer (see http://lwn.net/Articles/192214/). David
Zeuthen, one of the Red Hat engineers has made major progress on making one
of the desktop key components (called “hal”) work well, and we are now able
to use it on OLPC.

Marcelo Tosatti, one of the Red Hat OLPC staff has recently made the
“tickless” patches work on the Geode.  He's now at of order 50
interrupts/second and investigating further.  He also cleaned up the
USB-EHCI driver to stop polling and become interrupt driven, again reducing
wakeup overhead.

4. Drivers: Marcelo also tested v3106 of the Libertas boot2 code, which
should fix a number of outstanding USB problems we've observed, and tested
the updated Libertas mesh firmware.

Since we have no “legacy” DMA devices on our machine (e.g., floppy drives)
Marcelo also prepared a patch to recover the DMA-area memory usage, since
all our devices can address all of memory directly.

Andres Salomon worked on the Linux kernel touch-pad driver and testing the
new version of the touch pad from ALPS and the EC fix from Quanta that
allows us to talk to the device correctly.  The two samples we have in
Cambridge are working well.  He has also been integrating other patches
into our system.

5. Firmware: Mitch Bradley has made very good progress on eliminating the
need for VSA (virtual systems architecture) that emulates PCI registers on
the Geode; Mitch has identified all registers that need to be set up on
boot or resume. (While source for VSA is available, it requires obsolete
Windows tools to build and is probably unnecessary baggage.) Mitch will
start integration of this work into the firmware; we hope to do so in a
“step-wise” fashion, so that only one part of the system need change at a
time and so we can always do A-B comparisons of the changes in case
problems surface along the way.

Richard Smith tested a later version of the EC code in our firmware to fix
a battery overcharge problem and has prepared a version of the firmware for
the pre-BTest-2 build that will take place next week. With the advent of
the CAFE ASIC, we hope to run the PCI bus at 66mhz and some pin-outs have
had to change. He has also started going through LinuxBios to audit the
POST (power-on self test) codes.

Mitch Bradley and Dave Woodhouse will be in Shanghai next week for the
BTest-2 board and CAFE ASIC bring-up.

6. SJ Klein spent some time with Rob Savoye and John Gilmore testing Gnash
on the laptops (Gnash is a GNU Flash movie player). They were able to get
smooth playback for both flash video and animation. A file used for stress
testing that uses over 60M of memory played slowly but without hitches. An
activity for Ming (an open-source library used to create SWF-format movies)
and Gnash may be ready for the laptops in time for B2.

With a working Flash tool-chain, it will be very easy to script new
applications and small games; and many early education tools designed to be
cross-platform by working in flash will become available to us. Rob is
taking on new staff and looking for interface developers; he wants to give
Ming a GUI and to set up a cross-compiling environment for OLPC to help
future work.

7. Python: Mamading Ceesay, who has been a long-time advocate of teaching
Python to children, has offered to curate a collection of generative Python
games. He intends to get Pygames and Childsplay to run on the laptops, and
to help others produce tutorials using the games to show children how and
why to program.

Happy New Year

-walter

---
Walter Bender
One Laptop per Child
http://laptop.org