Arun Ramamurthy
2014-10-17 00:02:26 UTC
I am trying to solve a tearing issue that I am see when using directfb
I am running a qt 5.2 example application on DirectFb 1.7.6 on an embedded platforms with a 3.10 linux kernel.
The resolution is 800 by 480 and the frame buffer drivers provides a double buffer of 800 by 960.
There is no video memory and the driver allocates the frame buffer in system memory
When I used the command line parameter --dfb:desktop-buffer-mode=backvideo directfb recognizes the double buffer:
(*) FBDev/Mode: Switched to 800x480 (virtual 800x960) at 32 bit (RGB32), pitch 3200
However when I use --dfb:desktop-buffer-mode=backsystem I get :
(*) FBDev/Mode: Switched to 800x480 (virtual 800x480) at 32 bit (RGB32), pitch 3200
Can someone please explain this discrepancy?
Why can't I use the double buffer when specifying back system? Additionally when I specify backvideo the frame drops drastically and I still see the tearing.
Any insight is appreciated. I have the read archived post on the difference between backvideo and back system over here
http://mail.directfb.org/pipermail/directfb-users/2009-September/001886.html
Regards,
Arun Ramamurthy
I am running a qt 5.2 example application on DirectFb 1.7.6 on an embedded platforms with a 3.10 linux kernel.
The resolution is 800 by 480 and the frame buffer drivers provides a double buffer of 800 by 960.
There is no video memory and the driver allocates the frame buffer in system memory
When I used the command line parameter --dfb:desktop-buffer-mode=backvideo directfb recognizes the double buffer:
(*) FBDev/Mode: Switched to 800x480 (virtual 800x960) at 32 bit (RGB32), pitch 3200
However when I use --dfb:desktop-buffer-mode=backsystem I get :
(*) FBDev/Mode: Switched to 800x480 (virtual 800x480) at 32 bit (RGB32), pitch 3200
Can someone please explain this discrepancy?
Why can't I use the double buffer when specifying back system? Additionally when I specify backvideo the frame drops drastically and I still see the tearing.
Any insight is appreciated. I have the read archived post on the difference between backvideo and back system over here
http://mail.directfb.org/pipermail/directfb-users/2009-September/001886.html
Regards,
Arun Ramamurthy