Article ID: 000075159 Content Type: Troubleshooting Last Reviewed: 09/11/2012

Why is the Scatter-Gather DMA Controller Core's (SG-DMA) IRQ for descriptor_complete triggered before the descriptor is updated?

Environment

BUILT IN - ARTICLE INTRO SECOND COMPONENT
Description

You will see the descriptor_complete IRQ being triggered before descriptor writeback is updated. This could result in a syncronization issue as the status register is being updated before the descriptor is updated.

 

To workaround this issue you can manually access the last descriptor in the chain and verify that the 'owned by hardware' bit is set to 0.