AM57X: CMEM problems with IPC between ARM and DSP

Update:

It is working now. For anybody who is interested in, I will try to explain here. It is something like a summery of all threads I have found and lead to solve this whole IPC problem between ARM and DSP.
There are several steps you have to consider, to make IPC work between the ARM and DSP1:

1. New entries in the RSC table for the DSP1:
- Use a custom RSC table (processors.wiki.ti.com/.../IPC_Resource_customTable) and not the default one rsc_table_vayu_dsp.h in ipc_x_xx_xx_xx/packages/ti/ipc/remoteproc/
- 3 new defines have to be set to let the DSP know where the physical memory of CMEM is, where its own virtual memory is and the size of it.
Example:
#define DSP_CMEM_IOBUFS 0x85000000 => virtual address of the DSP memory section
#define CMEM_PHYS_IOBUFS 0xB0000000 => physical address of the CMEM (shared) memory section
#define DSP_CMEM_IOBUFS_SIZE (SZ_1M * 90) => size of the CMEM section

And don't forget the small modifications described in the custom table link, like change offset [18] to [19] and the addition of the new entry in the ResourceTable.


2. Correct allocation of the CMEM
- In my case the command line approach for CMEM, described here (processors.wiki.ti.com/.../CMEM_Overview) was not working properly, that's why I have to change it in the file am57xx-evm-cmem.dtsi. The location is in the Linux-SDK-Processor folder in board-support/linux-4.1.13+......../arch/arm/boot/dts/. There you have create an entry for the physical address described above.
Example:
cmem_block_mem_0: cmem_block_mem@b0000000 {
reg = <0x0 0xb0000000 0x0 0x0c000000>;
no-map;
status = "okay";
};

In the CMEM section below in this file, you can decide the amount of pools and each size of them.
Example:
cmem_block_0: cmem_block@0 {
reg = <0>;
memory-region = <&cmem_block_mem_0>;
cmem-buf-pools = <4 0x0 0x00100000>;
};
4 Pools with each size of 0x100000.

- To rebuild the new changes, you have to be in the Linux top level linux-4.1.13... and call the command make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- am57xx-evm.dtb
This will build a new dtb file, which you have to copy into the boot folder on the target and overwrite the existing one. The use the changes, you have to reboot the target first. After you can check it with cat /proc/cmem.

3. Using the CMEM commands on the ARM side and the Resource commands on the DSP side
- On the ARM side, you have to include the cmem.h file and the libs to use CMEM stuff.
- You have to use following commands in this order to use CMEM:
-> CMEM_init() => to init CMEM functions
-> virtualBuffer = CMEM_alloc(Size, &CMEM_params) => for a virtual buffer, where you can copy your data
-> CMEM_getPhys(virtualBuffer) => to get a physical address for the linked virtual buffer.

Then you can send the physical address via MessageQ_put to the DSP.

- On the DSP side you have to poll your MessageQ. To learn more about the MessageQ stuff, check out the example ex02messageq of DRA7xx_linux. After the ARM is sending a message with the physical address, you have to call Resource_physToVirt(physicalAddressCMEM, &virtualAddressDSP).
-> virtualAddressDSP is equal to DSP_CMEM_IOBUFS as described above. With this you can use the data you put in on the ARM side.



And that's the magic. Took me a long time to get everything together and I described this in the way I understood. Maybe it is a bit different from the correct way to understand, but at least it leads to a result. So if I am describing something wrong, I am sorry for that, please correct me.