AM5726: CMEM memory allocation for DSP usage

Pankil Shah

Part Number: AM5726

Hi,

We want to run some operations on DSP in AM57XX evm using OPENCL.

During opencl initialization it allocates whole partition of cmem for itself.

root@am57xx-evm:~# cat /proc/cmem Block 0: Pool 0: 1 bufs size 0xc000000 (0xc000000 requested)Pool 0 busy bufs:id 0: phys addr 0xa0000000 (cached)

Along with OPENCL, we need to allocate some memory in cmem that DSP can access and fill data in it.

But when we try to allocate memory in cmem it says:" can not allocate memory in this pool "because whole cmem partition is allocated for only opencl.

So is there any way so that we can get some cmem memory other than OpenCL?

Do we need extra pool or we can restrict Opencl to use whole cmem pool?

Please guide us and suggest solution in this issue.

Thanks,

Pankil.

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

The software team have been notified. They will respond here.

0 Garrett Ding over 8 years ago in reply to Biser Gatchev-XID

TI__Mastermind 43296 points

Pankil,

You can create another CMEM pool separated from OpenCL. CMEM pool can be defined in DTS file. Some useful links:

processors.wiki.ti.com/.../CMEM_Overview
e2e.ti.com/.../1831693

Regards,
Garrett

0 Pankil Shah over 8 years ago in reply to Garrett Ding

Expert 1040 points

Hi Garrett,

Thanks for the given suggestion.

As OpenCL captured whole CMEM chunk,
Can it possible that user application can borrow few chunk of contiguous memory from OpenCL through its APIs (if it have).

Can you please guide on this.

Thanks,
Pankil

0 Yuan Zhao over 8 years ago in reply to Pankil Shah

TI__Expert 4045 points

Hi Pankil,

You can allocate CMEM memory through OpenCL APIs in your OpenCL application, for example, "__malloc_ddr()". Please refer to TI's OpenCL user guide for more details. Also, you can look at the shipped OpenCL examples on your EVM to see how "__malloc_ddr()" is used.

downloads.ti.com/.../host-malloc-extension.html

- Yuan

0 Pankil Shah over 8 years ago in reply to Yuan Zhao

Expert 1040 points

Thanks Yuan for your valuable suggestion. We use this function to allocate memory as you suggested. But while we are printing the pointer where memory is allocated, this address is showing in the range of System RAM Range not in CMEM range. Does pointer returning of virtual address or its physical only?

0 Yuan Zhao over 8 years ago in reply to Pankil Shah

TI__Expert 4045 points

Hi Pankil,

The returned pointer from __malloc_ddr() is the virtual pointer in Linux address space, mapped from a physical address in CMEM. You can create a buffer with USE_HOST_PTR flag and pass it to a kernel running on DSP. From that kernel, you can print the pointer out, it would be the virtual pointer in DSP address space, mapped from the same physical address in CMEM. For details, please see TI OpenCL documentation: downloads.ti.com/.../host-malloc-extension.html

If the physical address really matters to you, you can call CMEM_getPhys() on the pointer returned by __malloc_ddr(). Make sure you compile with -D_FILE_OFFSET_BITS=64 because the returned physical address might be 36-bit.

Hope this helps.

- Yuan

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AM5726: CMEM memory allocation for DSP usage