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About maximum and recommended value of FB_MULTI_BUFFER

Question asked by Takayuki Ishii on Mar 19, 2018
Latest reply on Apr 4, 2018 by Takayuki Ishii

Hello community,

 

I have 3 question about envrionment valiable of FB_MULTI_BUFFER.

 

1) In iMX_Graphics_User's_Uide of Linux BSP document, FB_MULTI_BUFFER in Table

     of i.MX 6 FB API environment variables see that recommended values is 4 and maximum is 8.

 

      The other hand, in API description and syntax of fbGetDisplayByIndex, it say that

      "To use multiple buffers when rendering, set the environment variable FB_MULTI_BUFFER to an unsigned integer
      value, which indicates the number of buffers. Maximum is 3."

 

   That meen, if FB_MULTI_BUFFER > 3, fbGetDisplayByIndex() is failed and return NULL pointer,

   So in this case, we must use other API like a fbGetDisplay();

   Is it correct?

 

2)  What is a "hardware limitation of current IPU" in i.MX 6 FB API environment variables?

   Does It suggest that "i.MX6 X11 EGL is single buffered and there is no support for VSYNC."?

 

3) How to effect a FB_MULTI_BUFFER variable, if it is no IPU device like a i.MX6 SoloX?

 

Best regards,

Ishii.

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