ARM Technical Support Knowledge Articles

What causes the lockup_err bit to be asserted?

Applies to: PL330 AXI DMA Controller


This happens where there is insufficient space in the MFIFO for all the expected data. The controller can also be configured to generate an interrupt in addition to the lockup_err bit being asserted.

The lockup_err/interrupts do not indicate overflow of the MFIFO but indicate that there is insufficient space in the MFIFO for the expected data. The MFIFO can even be less than full at the time; the detection occurs when all of the running channels are prevented from executing a load, and the store queue has been emptied so there is no prospect of any more free space appearing in the MFIFO.  There might be some free space, but not enough for the beats required.

Rate this article

Disagree? Move your mouse over the bar and click

Did you find this article helpful? Yes No

How can we improve this article?

Link to this article
Copyright © 2011 ARM Limited. All rights reserved. External (Open), Non-Confidential