How to enlarge the shared-dma-pool on orin?

[Bryan_Zhong]

Platform:Jetson AGX Orin on custom carrier, R35.6

Hi,I am trying to enlarge cma size on orin, but after I changed the cma size in the dtb, after i recompiled and replaced the dtb, it doesn’t work, it seem like the cma size is limited to 512M.
The cma node in dtb:

linux,cma{
compatible = “shared-dma-pool”;
reusable;
size =<0x00 0x20000000>;
alignment =<0x00 0x10000>;
linux,cma-default;
status = “okay”;
};

I change the size property like this:
size =<0x00 0x80000000>;
or
size =<0x00 0x40000000>;

even I change the size from 512M to 2GB or other size,
when I use command ‘dmesg’,the kernel message shows the same result that the cma is 512M:

[.000000 ]Reserved memory: created CMA memory pool at 0x00oo000df6800000，size 512 MiB
[0.000000] OF: reserved mem: initialized node linux,cma，compatible id shared-dma-pool

Do you know how to enlarge the share-dma-pool?

Thanks!

[carolyuu]

Hi,
If the device cannot be flashed/booted, please refer to the page to get uart log from the device:
Jetson/General debug - eLinux.org
And get logs of host PC and Jetson device for reference. If you are using custom board, you can compare uart log of developer kit and custom board to get more information.
Also please check FAQs:
Jetson AGX Orin FAQ
If possible, we would suggest follow quick start in developer guide to re-flash the system:
Quick Start — NVIDIA Jetson Linux Developer Guide 1 documentation
And see if the issue still persists on a clean-flashed system.
Thanks!

[Bryan_Zhong]

You are a robot, aren’t you?

[DaneLLL]

Hi,
We don’t support extending it to 2GB. This looks to be duplicate of
Increasing size of BAR0 to 2GB in Endpoint Mode

[Bryan_Zhong]

Hi,
These two are similar,but not the same one.
How large does the cma size can be extend?I just find that the cma size is fixed.

[DaneLLL]

Hi,
The default size is the maximum size we validate. Further increase may trigger potential issues.