[maemo-developers] SDL, tearing, X overhead and direct framebuffer gfx

[From: Frantisek Dufka]

Siarhei Siamashka wrote:
> N800 hardware definitely supports tearsync. 

And 770 should too according to the schematics floating on the net. Only 
the code never made to official 770 kernel but is/was part of released 
N800 kernel. Sadly last time I tried and ported this code back to 770 
kernel it just hanged the device and the interrupt on TE pin never 
arrived. I'm suspecting the sossi TE pin needs to be enabled somehow via 
some platform specific (omap1) initialization code that was not part of 
N800 kernel. The failed attempt is here
http://fanoush.wz.cz/maemo/2.6.16.yuv420+tearsync-not-working.diff

Got no reply here
http://lists.maemo.org/pipermail/maemo-developers/2007-May/010156.html
but something here
http://www.gossamer-threads.com/lists/maemo/developers/22701#22701

Also on the similar 'banging my head against the wall' kernel topic - 
some weeks ago I downgraded my N800 back to OS2007 (as I have N810 with 
it, the N800 touchscreen is much worse in OS2008 and I like speed of 
Opera and the system i general). Also since I boot from mmc I flashed 
only initfs and kernel (i.e. not bootloader). Then I noticed my external 
mmc slot does not work. Flashed to OS2008 back - it worked again, 
flashed back to OS2007 - no luck even with original Nokia kernel. I 
spent some time digging in kernel source and even backporting changes in 
mmc stack from 2.6.21 to 2.6.18 with no luck. Finally I had an idea to 
flash bootloader too (over USB, kernel and initfs can be done on the fly 
from the device so one could sort of dual boot between OS2007 and 8). 
After doing this my external mmc slot magically works again in OS2007 
(NOLO is downgraded from 1.1.7 to 1.1.6).

This was a bit discouraging and tells me something about chances of 
getting tearsync code working without proper HW initialization and 
bootloader sources :-)

Frantisek