imx7d using dma to transfer eim data

864535720 — Wed, 08 Jul 2020 07:38:36 GMT

Hello everyone
my development board is IMX7DSABRE. Linux kernel version is 4.9.88.
When I use dma to transmit EIM data to FPGA on imx7d, when I write data to EIM bus, some problems occur. My EIM bus data width is configured to 16bit, I write 16 bytes of data to the bus each time:
0x1234 0x1235 0x12346 0x1237 0x1238 0x1239 0x123a 0x123b
My FPGA can receive these 16 bytes of data, but it also receives an additional 16 bytes of 0 data. The 0 data was received because the EIM bus generated 8 more write signals.
Normally, according to the configuration of my data line width, when 16 bytes occur, only 8 write signals need to be generated, but actually 16 write signals are generated. The waveform diagram is as follows:

My dma code configuration is as follows:
dma_m2m_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
dma_m2m_config.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
dma_m2m_config.src_maxburst = EIM_WRITE_SIZE/2;
dma_m2m_config.dst_maxburst = EIM_WRITE_SIZE/2;
dmaengine_slave_config(dma_m2m_chan, &dma_m2m_config);
dma_m2m_desc = dma_m2m_chan->device->device_prep_dma_memcpy(dma_m2m_chan, dma_dst, dma_src, length, DMA_MEM_TO_MEM);

I want to know why there are 16 write signals？

At the same time I tried to configure different values for dst_addr_width and src_addr_width, but no matter how I configure it, there will always be redundant write signals. How should I solve this problem?

At the same time I tried dst_addr_width and src_addr_width to configure different values, such as:
dma_m2m_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
dma_m2m_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;

dma_m2m_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
dma_m2m_config.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;

dma_m2m_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
dma_m2m_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;

dma_m2m_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
dma_m2m_config.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;

dma_m2m_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
dma_m2m_config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;

dma_m2m_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
dma_m2m_config.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;

dma_m2m_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
dma_m2m_config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
But no matter how I configure it, there will always be redundant write signals. How should I solve this problem?

Re: imx7d using dma to transfer eim data

igorpadykov — Wed, 08 Jul 2020 11:25:57 GMT

Hi 其东刘

for eim burst with dma cases may be useful to look at

sect.9.7.5.4 Burst Clock Divisor (BCD), sect.9.7.5.8 AXI (Master) Bus Cycles Support

i.MX 7Dual Applications Processor Reference Manual

For example sdma source memory address was aligned according to burst size,

PSZ, BL settings in EIM_CSnGCR1 register. First may be useful to test configuration

with barmetal sdk:

rt-thread/eim_test.c at master · RT-Thread/rt-thread · GitHub

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: imx7d using dma to transfer eim data

nx5216 — Thu, 09 Mar 2023 09:26:21 GMT

HI, did you solve the problem, now I have the same problem, could you tell me the solution. my email: nx5216@163.com

i.MX Processorsのトピックimx7d using dma to transfer eim data

imx7d using dma to transfer eim data

Re: imx7d using dma to transfer eim data

Re: imx7d using dma to transfer eim data