adi_mdma_IsCopyInProgress() always returning true on adi_mdma_CopyList() with source XMODIFY = 0

Hi,

From your description we understand that you are using MDMA copy in descriptor list mode to clear 4096 bytes (4 descriptors × 1024 bytes) of SDRAM. A small 32-byte zero-filled buffer is used as the source. The intent is to repeatedly copy the 32-byte zero buffer across the full 4 KB region. Please confirm our understanding.

If it's correct, please refer the attached project which copy the data correctly.

 MemCopyListMode.zip

Initially, the configuration had:

Source XCount = 1, XModify = 0
Destination XCount = 32, XModify = 32

This caused only 32 bytes to be transferred, and the DMA stalled. Each MDMA descriptor is configured to transfer 1024 bytes (i.e., MEMCOPY_BYTES_PER_DESC = 1024). Since the MSIZE is 32 bytes, that means:

1024 bytes / 32 bytes-per-transfer = 32 transfers

To match this, the source must perform 32 transfers of 32 bytes each. Setting XCount = 32, XModify = 0 tells MDMA to read the same 32-byte source buffer repeatedly without incrementing. The destination will receive 32 transfers, filling 1024 bytes with repeated 32-byte data.

If XCount is incorrectly set to 1 in the source, only 1 transfer of 32 bytes is initiated. The destination waits for 32 transfers leads to DMA hang issue. 

Regards,
Nandini C

Thank you Nandini, problem solved.

The error was in XCount value for the source descriptor, which must not reflect the size of the 32-byte buffer but the total number of MSIZE transfers that need to be performed by the DMA controller from source to destination.

Thank you Nandini, problem solved.

The error was in XCount value for the source descriptor, which must not reflect the size of the 32-byte buffer but the total number of MSIZE transfers that need to be performed by the DMA controller from source to destination.