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How to set imx7d dma single transmission size unit?

Question asked by 其东 刘 on May 21, 2020
Latest reply on May 21, 2020 by igorpadykov

Hello everyone
my development board is IMX7DSABRE. Linux kernel version is 4.9.88
I use dma on imx7d to transmit the data on the eim bus. Now my data can be transmitted normally, but I found that dma unpacked and transmitted my data during the transmission process. My code is set to transmit 2KByte of data every time DMA, but I measured the waveform of EIM_OE / EIM_RW, and found that DMA split the 2KByte data into 64 packets for transmission, each packet of 32 bytes. Why does DMA split 2KByte data into 64 packets for transmission?
The waveform I measured is shown below: