How to change from gbm(drm) backend to triple buffering?

How to change from gbm(drm) backend to triple buffering?

I want to change the number of buffering in the gbm(drm) backend.

However, the gbm backend seems to be fixed with double buffering.

root@~# cat /sys/kernel/debug/dma_buf/bufinfo

Dma-buf Objects:
size flags mode count exp_name ino

05529600 00000000 00000005 00000004 drm 00005855
Exclusive fence: mali mali.timeline signalled
Attached Devices:
10100000.gpu
Total 1 devices attached

05529600 00000000 00000005 00000004 drm 00007459
Exclusive fence: mali mali.timeline signalled
Attached Devices:
10100000.gpu
Total 1 devices attached

please help.