Using XMC and MAR registers - C6678

Hi everyone,

I'm using Hyperlink to transfer data between two C6678 (DSP A and B). One of the Hyperlink segments is mapped on DSP A's MSMC. To perform this transfer, DSP A writes a data on its local MSMC (hyperlink mapped), sends an interruption to DSP B, and DSP B reads the data.

At every execution, the first transfer works successfully, but the second transfer doesn't work : DSP B reads an old value. This issue is probably due to the Cache : I enable L1D and L1P cache and disable L2 cache (I have to keep this configuration).

First I tried to modify MAR register corresponding to MSMC in order to disable cache for this region, but this register (MAR12) is read-only.

So I chose to use XMC to extend this region to 0xA000_0000 and disable cache (with MAR160) with the code at the bottom. I also modified MAR64 register, wich is corresponding to Hyperlink region (0x4000_0000), but it seems to have no effect : DSP B still reads an old value.

I don't know if it's important : when I open ROV > Cache > EnableMARs, I see all MAR registers, except 64 and 160, registers I've modified. However, with MemoryBrowser tool, I can see the right value (0 because I set cacheability and prefetcheability to 0) at 0x0184_8100 (MAR64) and 0x0184_8280 (MAR160).

I use this following code to initialize Cache (wich is coherent with RTSC platform definition and GEL file), XMC and MAR registers.

/*
* Using MPAX register 3
* Segment size : 4 MB (0x15 = 0b10101)
* Logical address : 0xA000_0000 (after DDR3) (0x00A00)
* Physical address : 0x0C00_0000 (MSMC) (0x000C0)
* Protection for supervisor and user : read, write, no execution (110110)
* MAR Register index for 0xA000_0000 : 160 (0xA0)
* */

CACHE_setL1PSize(CACHE_L1_0KCACHE);
CACHE_setL1DSize(CACHE_L1_0KCACHE);
CACHE_setL2Size(CACHE_0KCACHE);

CACHE_setL1PSize(CACHE_L1_0KCACHE);
CACHE_setL1DSize(CACHE_L1_0KCACHE);
CACHE_setL2Size(CACHE_0KCACHE);

CSL_XMC_XMPAXH highStruct = {0x000C0, 0x15};
CSL_XMC_XMPAXL lowStruct = {0x00A00, 1, 1, 0, 1, 1, 0};

CSL_XMC_setXMPAXH(3, &highStruct);
CSL_XMC_setXMPAXL(3, &lowStruct);

CACHE_setMemRegionInfo(160, 0, 0);
CACHE_setMemRegionInfo(64, 0, 0);

To read the data, I use the following line :

Hyplnk_Status[Hyplnk_NumCore] = *((volatile char *)0x40177009);

Does anyone had this issue ?

Thanks for your time.