Support of single frame buffer on OMAP4 display

vperi peringat

Hi ,

Here is the use case, wondering how can be done in OMAP4, please point if any references:

1. There will be only 1 frame buffer from which display will be done every frame

2. The video data to be displayed is created in small private buffers.

3. A Hardware logic will need to update the frame buffer , using DMA or something , such that there will be no tearing (ie copying from private buffer to frame buffer should not happen when that particular line is being displayed while causnig tearing). For this the hardware must be aware of what is being currently displayed ie knowledge of line being drawn on screen.

4.CPU cannot be used for this task as its too slow, and dont want to burden it.

Thanks

vperi

over 12 years ago

0 vperi peringat over 12 years ago

Prodigy 30 points

Hello folks,

Can someone respond to this question, basically as to how blitting is achieved for 1 frame buffer use case.

0 Boyko Kazakov over 12 years ago

TI__Genius 10965 points

Hi Vperi,

There are implementation for display kernel driver even in a u-boot driver.

Please examine the omap 4 TRM "Display Subsystem" chapter to understand how to properly use the display IP and DMA of the device.

Here you can check how to set bootargs to enable display output

http://omappedia.org/wiki/Bootargs_for_enabling_display

Regards,

Boyko

0 vperi peringat over 12 years ago in reply to Boyko Kazakov

Prodigy 30 points

Boyko,

I have read the DSS chapter. My question was more on Android SurfaceFlinger strategy wherein private buffers are blitted to a single frame buffer. Main requirement for such kind of application is While the screen is being drawn , a "blitter" must be aware that "hey , this is current line being drawn on display, so let me not step into the beam after that , instead I ll write to framebuffer contents which beam has already displayed". So this use case needs multiple local buffers (created by GPU / CPU / Compositor) , blitted onto single frame buffer, and display always shows from single frame buffer.

Does OMAP 4470's CGPU responsible for this functionality ?

0 Boyko Kazakov over 12 years ago in reply to vperi peringat

TI__Genius 10965 points

Yes, The SGX driver is responsible for that functionality.

Nevertheless more information how that is done cannot be discussed in the omap4 forum.

Regards,

Boyko

Processors

Processors forum

Support of single frame buffer on OMAP4 display