GSG: OMAP35x Graphics SDK Additional Procedures

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Switching between FrontEGL and FlipEGL Modes

When using FrontEGL, SGX fb updates happen directly on single framebuffer (front buffer). Not really recommended except for SGX benchmarking as it will result tearing artifacts at high resolution and frame rates.

FlipEGL uses ping-pong scheme for graphics updates and this is the default EGL library used if /etc/powervr.ini is not present.

Modify the powervr.ini file under the <your_target_file_system>/etc/init.d to select between the FrontEGL or FlipEGL mode.

Flip support requires increasing the virtual yres size in fb0 plane and allocating appropriate memory for framebuffer.

Use the following command to increase the virtual yres size in fb0 plane. The vyres size needs to be set to three times the height of the screen size for triple buffering. For eg:- OMAP3 EVM LCD fb with dimensions 480x640

target $ fbset -vyres 1920 

More solutions for vertical tearing

If you are running on a Linux console frame buffer (/dev/fb0) the following shared object may work better for you to prevent vertical tearing at the center of the screen.  This object is often found in /usr/lib or /usr/local/lib.  libpvrPVR2D_LINUXFBWSEGL.so.

Switching the display output from LCD to DVI

Switching the display output from LCD to DVI during boot time

This can be done by changing in the bootargs to include the following

For 16bpp :

omap-dss.def_disp="dvi" omapfb.video_mode="720x480MR-16@60"

For 32bpp :

omap-dss.def_disp="dvi" omapfb.video_mode="720x480MR-24@60"

For example, in case of NFS mount

OMAP3EVM # setenv bootargs console=ttyS0,115200n8 noinitrd rw ip=dhcp  
root=/dev/nfs nfsroot=<nfshost>:<rootpath>,nolock mem=128M omapfb.vram="4M" 
omap-dss.def_disp="dvi" omapfb.video_mode="720x480MR-16@60"

Switching the display output from LCD to DVI during run time after boot

Step 1: Refer here to change the display output from LCD to DVI after boot, from the command line, on target.

Step 2: On target, perform the command "fbset -depth 32 -rgba 8/16,8/8,8/0,8/24"

Step 3: On target, perform "/etc/init.d/rc.pvr stop" followed by "/etc/init.d/rc.pvr start"

After this, the demos should run properly on DVI.

Testing the support for ARGB8888 in Frame Buffer Driver

The bootargs need to be changed as given below.

OMAP3EVM # setenv bootargs 'console=ttyS0,115200n8=noinitrd=rw ip=dhcp 
root=/dev/nfs nfsroot=<your nfs_path>,nolock, mem=128M omapfb.vram="4M" 
omapfb.video_mode="640x480MR-24@60" omap-dss.def_disp="dvi"'

Use fbset to configure ARGB8888 mode for framebuffer memory

target $fbset -rgba  8/16,8/8,8/0,8/24 

Note that if you are switching to ARGB8888 mode after bootup it is mandatory to reload omaplfb.ko kernel module