about AXI_VFIFO

[Monster-Kee]

I tried to use the AXI_vfifo module you wrote, and I tried to configure it as a single channel FIFO. The other side is connected to a DDR MIG controller, it seems that the input of the FIFO is normal, and the AXI reading and writing of the MIG are also normal, but the FIFO has no output. I don't know where the problem lies at the moment

[ThomasVec]

I have the same problem with the simulation of the vFIFO. It seems that the decoding module does not start decoding. The data from the vFIFO rd goes to the decoding module, with a valid signal. The decoding module does not terminate the data with Ready.

Used Parameters for vFIFO:
-- AXI channel count
axi_ch => 1,
-- Width of AXI data bus in bits
axi_data_width => 32,
-- Width of AXI address bus in bits
axi_addr_width => 32,
-- Width of AXI wstrb (width of data bus in words)
axi_strb_width => 32/8,
-- Width of AXI ID signal
axi_id_width => 3,
-- Maximum AXI burst length to generate
axi_max_burst_len => 256,
-- Width of AXI stream interfaces in bits
axis_data_width => 32,
-- Use AXI stream tkeep signal
axis_keep_enable => 1,
-- AXI stream tkeep signal width (words per cycle)
axis_keep_width => 32/8,
-- Use AXI stream tlast signal
axis_last_enable => 1,
-- Propagate AXI stream tid signal
axis_id_enable => 1,
-- AXI stream tid signal width
axis_id_width => 3,
-- Propagate AXI stream tdest signal
axis_dest_enable => 1,
-- AXI stream tdest signal width
axis_dest_width => 3,
-- Propagate AXI stream tuser signal
axis_user_enable => 1,
-- AXI stream tuser signal width
axis_user_width => 1,
-- Width of length field
len_width => 8,
-- Maximum segment width
max_seg_width => 256,
-- Input FIFO depth for AXI write data (full-width words)
write_fifo_depth => 64,
-- Max AXI write burst length
write_max_burst_len => 16,
-- Output FIFO depth for AXI read data (full-width words)
read_fifo_depth => 128,
-- Max AXI read burst length
read_max_burst_len => 16

[ThomasVec]

I did further research in the decoding module, but I am not a Verilog developer and therefore limited in my analysis. But I identified the following signals as part of the problem: seg_empty is 1 because the wr and rd pointers are the same. No write is triggered because ctrl_fifo_wr_en remains 0, although the SOP is recognised see ctrl_fifo_wr_sop. Is ctrl_fifo_wr_en not set because seg_valid[1] = Undefined? And why is this a 2 bit vector?

[ivansun1688]

Hi,

currently I set axi_data_width=256, ch = 1, and then set axis_data_width=axi_data_width/2, max_seg_width = axi_data_width/2, and then the vfifo works.

if axi_ch=1 then set axis_data_width=axi_data_width and max_seg_width = axi_data_width, parameter SEG_CNT will to be 1, and parameters in encode/decode fifo are not correctly calculated and the vfifo will failed.

Thanks, please take a review.