Linux/AM5728: CMEM region 0xA0000000 - 0xABFFFFFF usage

Darshan Patel7

Intellectual 455 points

Part Number: AM5728

Tool/software: Linux

Hi,

Which module is using DDR memory region 0xA0000000 - 0xABFFFFFF ( 192 MB) ? For what purpose ?

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

Could you please provide more details to your question?

0 Darshan Patel7 over 9 years ago in reply to Biser Gatchev-XID

Intellectual 455 points

Hi,

In latest processor sdk, linux device tree has cmem entry which reserves 192 MB DDR space. I want to understand which module is using this region ? It could be for IPC/ Data sharing between A15 and other cores.

0 Biser Gatchev-XID over 9 years ago in reply to Darshan Patel7

TI__Guru**** 393215 points

Thanks. I have notified the software team. They will respond here.

0 Yordan Kovachev over 9 years ago

TI__Guru**** 161600 points

Hi,

Which kernel version is this? How did you determine that this exact memory space is used?
Is this AM5728 GP evm or a custom board?

Best Regards,
Yordan

0 Darshan Patel7 over 9 years ago in reply to Yordan Kovachev

Intellectual 455 points

Hi Yordan,

It's kernel version 4.4 (Linux am57xx-evm). It is AM5728 GP EVM.

# cat /proc/iomem | grep cmem

a0000000-abffffff : CMEM

As reserved in file arch/arm/boot/dts/am57xx-evm-cmem.dtsi .

0 Yordan Kovachev over 9 years ago in reply to Darshan Patel7

TI__Guru**** 161600 points

Hi,

The CMEM is explained in processors.wiki.ti.com/.../CMEM_Overview
This memory section is available the continuous memory allocated buffers (that will be shared with another processor, i.e. cortex m4, sgx, dsp, etc..).
There are also the following reserved memory locations:
reserved-memory {
#address-cells = <2>;
#size-cells = <2>;
ranges;

ipu2_cma_pool: ipu2_cma@95800000 {
compatible = "shared-dma-pool";
reg = <0x0 0x95800000 0x0 0x3800000>;
reusable;
status = "okay";
};

dsp1_cma_pool: dsp1_cma@99000000 {
compatible = "shared-dma-pool";
reg = <0x0 0x99000000 0x0 0x4000000>;
reusable;
status = "okay";
};

ipu1_cma_pool: ipu1_cma@9d000000 {
compatible = "shared-dma-pool";
reg = <0x0 0x9d000000 0x0 0x2000000>;
reusable;
status = "okay";
};

dsp2_cma_pool: dsp2_cma@9f000000 {
compatible = "shared-dma-pool";
reg = <0x0 0x9f000000 0x0 0x800000>;
reusable;
status = "okay";
};
};
defined in am57xx-beagle-x15-common.dtsi.

Best Regards,
Yordan

0 Darshan Patel7 over 9 years ago in reply to Yordan Kovachev

Intellectual 455 points

Hi Yordan,

Thanks for your input.

CMEM and CMA both are used for physical contiguous buffer allocation.

I know specifically, CMA regions are used for allocating code, data and other sections of IPU and DSP firmware.

I want to know for which specific purpose CMEM is used in processor SDK? Is it used by DSP/ gstreamer pipeline/ IPU2 video codec data, etc ?

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Linux/AM5728: CMEM region 0xA0000000 - 0xABFFFFFF usage