Vsync and double buffering

Has anyone implemented vsync and video buffering switching on the beagleboard, ideally for a DSS2 fb? If so, any pointers?

Cheers

Rob

Just yesterday I pushed changes to my DSS2 repository adding OMAPFB_WAITFORVSYNC ioctl. Double buffering can be implemented with panning.

  Tomi

Just yesterday I pushed changes to my DSS2 repository adding OMAPFB_WAITFORVSYNC ioctl. Double buffering can be implemented with panning.

Thanks Tomi, that's great timing :slight_smile:

Rob

Just yesterday I pushed changes to my DSS2 repository adding
OMAPFB_WAITFORVSYNC ioctl. Double buffering can be implemented with
panning.

I'm have difficulty working out how to setup omapfb for panning. I did the following:

Built a 2.6.27 kernel from Tomi's tree with 1 framebuffer enabled

Passed bootargs: video=omapfb:vram:8M omapfb.mode=dvi:1024x768MR-24@60 omapfb.vram=0:6M

fbset -fb /dev/fb0 -g 1024 768 1024 1536 32

# cat framebuffers
0 p:804b5000 v:c9000000 s:6291456 t:gfx

# cat overlays
gfx t:lcd x:0 y:0 iw:1024 ih:768 w:1024 h:768 e:1
vid1 t:lcd x:0 y:0 iw:0 ih:0 w:0 h:0 e:0
vid2 t:lcd x:0 y:0 iw:0 ih:0 w:0 h:0 e:0
l4-ovl t:l4 x:0 y:0 iw:0 ih:0 w:0 h:0 e:0

# cat managers
lcd t:dvi
tv t:tv
l4 t:none

# cat displays
dvi e:1 u:1 t:0 h:1024/80/48/32 v:768/3/15/4 p:57600 r:0 i:0
tv e:0 u:-1 t:0 h:720/0/0/0 v:574/0/0/0 p:0 r:0 i:0

# echo gfx y:768 > overlays
omapfb omapfb: setup overlay failed

I don't seem to have succeeded in mapping a double height framebuffer to the physical display. What am I missing?

Thanks

Rob

Tomi Valkeinen <tomba@iki.fi> writes:

You are changing the position of the overlay on the screen there. That is not what you want. You want panning:

http://www.mail-archive.com/linux-fbdev@vuser.vu.union.edu/msg04109.html

It's been some time since I tested panning on omapfb, but it _did_ work at least =). Some new changes may have broken something, so keep me posted if you can't get it to work.

  Tomi

You are changing the position of the overlay on the screen there. That is
not what you want. You want panning:

http://www.mail-archive.com/linux-fbdev@vuser.vu.union.edu/msg04109.html

It's been some time since I tested panning on omapfb, but it _did_ work at
least =). Some new changes may have broken something, so keep me posted if
you can't get it to work.

It still works. Very well. :slight_smile:

Robert

[from a private mail conversation, copy to the list]

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