Tearsync now works with 770

April 7th, 2008 by fanoush (

)

Got this finally working. Too bad it is almost useless now, we needed it years ago ;-) What is tearsync? It is feature of omapfb driver that allows video playback without tearing effect. This feature is enabled in N8x0 kernel but never was part of Nokia 770 2.6.16 kernel shipped with any firmware. Luckily when first N800 2.6.18 kernel was released there was tearsync support added also in drivers for 770! All that was needed was to backport it to 2.6.16 kernel, right? Well, no. I did but it didn't work.

Only recently I've seen some strange issues with N800's MMC slot when going back to OS2007 and become aware of 'pin multiplexing' issue. Many pins of OMAP chip can be configured in software to have specific signal routed to it and this setting is done in bootloader. So maybe TE pin was simply not enabled? Too bad that any recent OMAP1 datasheet I could find had SoSSI documentation missing. Then I found in Google cache this text "revision D changes: ... removed all references to: ... Specially Optimized Screen Interface (SoSSI) ... deleted SoSSI function from the signal names with the following ball numbers ...". So after additional bit of googling (thanks Serge) and figuring out what all this means the answer is "ball G20, register 4, value 6, offset 6".

Funny thing, after setting G20 pin muxing correctly, the one year old code now magically works with no other change :-) If you still care for 770, you can get the kernel from Mplayer ITT thread here.

248 words posted in Maemo, Nokia 770 (1615 views) • 3 comments

This entry was posted on Apr 07, 2008 at 01:55:20 pm and is filed under Maemo, Nokia 770. You can follow any responses to this entry through the RSS 2.0 feed, or leave a response (below) .

3 response(s) to Tearsync now works with 770

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pH5 [Visitor] says:
04/07/08 @ 15:57
Oh well, congratulations on your persistance! I can only begin to imagine how it feels to realize after one year that the problem was just one flipped bit of an (as it seems) intentionally undocumented pin mux register.
Nice use of the google cache :)

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ossi1967 [Visitor] says:
04/07/08 @ 18:51
As a loyal 770 user, I'm happy to read things like these... Makes me happy even though I'm not quite sure if it will be useful for me: I understand it has advantages when playing videos with mplayer. Would anything else improve? (Like the built-in video player?) Or is it only relevant for software that knows about this feature?
fanoush [Member] says:
04/09/08 @ 22:06
ossi1967: yes it works only in mplayer or other software that uses direct framebuffer access with tearsync flag. Built-in video player is not improved. Still, mplayer is better for video so it is not that bad :-)

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fanoush