Video Latency occurs when the screen frequency is set to 24Hz on TMS320DM8168

GUERIN Yoann

Other Parts Discussed in Thread: TMS320DM8168

Hello everyone,

I'm currently working on a TMS320DM8168 with a PU SGX530 GPU. When the display mode of the screen is set to 24Hz, i noticed a latency between 300 and 500 ms on the video compared to the case when it is set to 60Hz. I did many tests to see if it came from the software and it looks like it comes from the GPU.

Therefore i was wondering if the output mode of the screen (and especially the frequency) could have an influence on the speed of treatment of GL commands (adding a delay?) . Are there some paramaters to influence this latency at initialisation ?

The last command used is "eglSwapBuffers".

Thank you.

over 9 years ago

0 Pavel Botev over 9 years ago

TI__Guru**** 170625 points

Hi Guerin,

Are you using DM816x TI EVM or custom board?

Are you using EZSDK 5.05.02.00?

"Screen frequency" - do you mean the pixel clock frequency (sysclk13 or sysclk15 or sysclk17) or other sysclkx?

Regards,
Pavel

0 GUERIN Yoann over 9 years ago in reply to Pavel Botev

Prodigy 190 points

Helllo Pavel,

Thank you for your answer.

I'm using a custom board.
Yes i'm using the EZSDK 5.05.02.00.
By Screen Frequency i meant the vertical clock (Image clock, number of updates of the screen per second).

Regards,
Guerin.

0 Pavel Botev over 9 years ago in reply to GUERIN Yoann

TI__Guru**** 170625 points

Hi Guerin,

I can not locate such clock signals (vertical clock, image clock) in the DM816x datasheet/TRM.

Can you provide the the steps to reproduce this issue? How exactly you change that vertical/image clock frequency?

Regards,
Pavel

0 GUERIN Yoann over 9 years ago in reply to Pavel Botev

Prodigy 190 points

The clock i'm refearing to is really not an hardware one but only the frequency of update of the screen (f=24Hz : the screen is looking for new frames 24 times every sec). I see that you go straight for the deep hardware stuff so i might not be in the right forum, if so i apologize.

Once again i'm just trying to understand how modifying the output mode of the screen could add 300ms of latency in the GPU (SGX530 GPU) knowing that my previous mode was mode "1920x1080 60Hz CEA" and the new one is "1920x1080 24Hz CEA".

0 Pavel Botev over 9 years ago in reply to GUERIN Yoann

TI__Guru**** 170625 points

Processors

Processors forum

Video Latency occurs when the screen frequency is set to 24Hz on TMS320DM8168