Disable the clock supplied to the DMA controller logic. This instantly freezes the DMA state machine but may cause bus hangs if a transfer was in progress.
If you are using a Programmable Logic Device (PLD)—such as an FPGA or CPLD—as a PCIe endpoint, disabling DMA isn't always as simple as flipping a driver switch. You have to kill it at the hardware configuration level.
If you need to temporarily disable DMA for debugging purposes but want to keep the infrastructure: how to disable dma on pld
| Problem | Likely Cause | Solution | |---------|--------------|----------| | DMA still active after register write | Write didn't take effect (wrong address/bus width) | Use debugger to read back register; check endianness. | | System hangs after disabling DMA | Disabled DMA while burst in progress | Implement a flush or wait for busy=0 before disabling. | | Peripheral fails after DMA off | Peripheral expects DMA ack | Reconfigure peripheral for PIO (programmed I/O) mode. | | DMA re-enables spontaneously | Reset manager reinitializes DMA | Hold reset line of DMA controller separately. |
Disabling DMA on a PLD can be achieved at four distinct levels, from most hardware-centric to software-driven: Disable the clock supplied to the DMA controller logic
You must determine which of these pathways is active in your design before you can disable it.
In the realm of digital design and hardware security, Programmable Logic Devices (PLDs)—including Complex Programmable Logic Devices (CPLDs) and Field-Programmable Gate Arrays (FPGAs)—serve as the backbone of modern embedded systems. They offer flexibility, speed, and the ability to implement custom logic at the hardware level. However, with great power comes great responsibility, particularly regarding Direct Memory Access (DMA). You have to kill it at the hardware configuration level
: On the scheduled day, keep your PLD switched on and connected to the internet