Hi Sam, Interesting find. Fundamentally, chdr_frame was designed to buffer and release on packet boundaries. This is due to the crossbar being packet switched and ensures packets flow through the crossbar at full rate. Generally, that is only important for sample data, which could have large packets generated slowly due to a low sample rate.
All that said, I am not seeing why switching to axi_fifo_flop2 is causing an issue. chdr_framer is not used anywhere in the settings bus data path. I wonder if there is a more complex interaction going on here. The flow_control_responder in noc_shell does use chdr_framer and its output does eventually mux with response packets generated from setting bus writes. Do you send these commands only while streaming? If so, can you try to send them when not streaming and see if you have the same issue? Jonathon On Wed, Oct 31, 2018 at 5:19 AM Samuel Prager <spra...@usc.edu> wrote: > Hi Jonathon, > > I have identified the cause of this problem as being chdr_framer.v. It > appears to not be adhering to the axi_stream protocol and is holding onto > packets until the fifo is full even when o_tready is asserted, causing the > described behavior. > > The root cause is the switch to axi_fifo_flop2 for the header fifo > (changed with commit that eb0ae36). The problem is fixed completely by > switching this back to an axi_fifo_short. > > Thanks, > > Sam > On Oct 25, 2018, 7:36 PM -0700, Samuel Prager <spra...@usc.edu>, wrote: > > Hey Jonathon, > > I had a chance to debug this a little further (On an N300) and have > observed the following behavior: > > The command packets are getting through to the radio block but are being > buffered somewhere along the line so that the first command is either not > received or not processed until exactly 16 have been sent. > > So if I am sending commands in a loop, there is a 16 command delay before > the settings bus writes and a rx command is triggered in the radio. > > This seems to indicate that there is a buffer somewhere that doesn’t pass > the commands until it is full. > > Any thoughts on what the culprit could be? > > Sam > On Oct 23, 2018, 11:17 PM -0700, Jon Pendlum <jon.pend...@gmail.com>, > wrote: > > Hey Sam, > > There have been some changes to noc_shell, maybe they are related to your > issue. If you want to try to debug this on the FPGA, I suggest using > chipscope on the file cmd_pkt_proc.v. That is the state machine that > receives command packets and issues settings bus writes. You should be able > to see your command packets come in and get processed by the state machine. > You can double check the command packet / timed command vita time versus > the radio core's vita time. You can also see if the state machine gets > stuck in a certain state. > > Jonathon > > On Wed, Oct 24, 2018 at 9:44 AM Samuel Prager <spra...@usc.edu> wrote: > >> Hi Jonathan, >> >> Just following up on this. I have switched to the UHD 3.13 release + FPGA >> version 5.2. This issue still persists. >> >> Is it possible that a change to UHD could be causing this to not work? >> >> If anyone can confirm that they are able to send commands to the radio >> block from an rfnoc block in recent versions of UHD it would help a lot. >> >> Thanks, >> >> Sam >> >> On Oct 22, 2018, 1:06 PM -0700, Samuel Prager <spra...@usc.edu>, wrote: >> >> Hi Jonathan, >> >> Yes I add my block and the radio block, connect them and tell my block to >> send commands to radio block. I have confirmed today that the simulation >> still works correctly in Vivado 2017.4 — the settings registers are written >> as expected, an rx command is generated in the radio and the correct number >> of samples are streamed back into the tb_streamer. >> >> Sam >> On Oct 21, 2018, 9:20 AM -0700, Jon Pendlum <jon.pend...@gmail.com>, >> wrote: >> >> How does your testbench work? Do you add the radio core block, send timed >> commands to it, and see the outputs toggle? >> >> On Sat, Oct 20, 2018 at 1:05 PM Samuel Prager <spra...@usc.edu> wrote: >> >>> Hi Jonathon, >>> >>> Thanks for the response! Yes I’m using ce_clk and ce_rst. Thanks for >>> sharing your code — the only real difference I see is that you increment >>> the seq_num. I am leaving it as 12’b0 — could this be causing an issue? >>> >>> I should also say that In my case, the command packets are being sent to >>> the radio block to trigger timed receive commands in order to reduce the >>> number of software sr_writes. >>> >>> Here’s my code just in case: https://pastebin.com/Asgj7Jw2 >>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__pastebin.com_Asgj7Jw2&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=opIuWAKmywF059tAs2i3Pg&m=3R0ikh1a2qoRPbHbjCY1HwGNVLITPElEnwQCWxi47Ds&s=EKhzTryz-igseKzyOz7C26jOwnxBLW-ALSJzn7z5bYY&e=> >>> . >>> >>> This is something that was simulated/verified and worked in the past, >>> but perhaps a change has been made that prevents this from working? >>> >>> I will try a release tag as soon as possible — however this is something >>> I’ve been seeing for a couple of months now that has kept me on pre-2017.4 >>> releases. >>> >>> Sam >>> On Oct 19, 2018, 8:17 PM -0700, Jon Pendlum <jon.pend...@gmail.com>, >>> wrote: >>> >>> Hi Sam, >>> >>> I am using command packets to tune the DDC block's DSP frequency. Are >>> you using ce_clk and ce_rst for clock and reset? Here is my code if you >>> want to take a look: https://pastebin.com/1AeHFb0J >>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__pastebin.com_1AeHFb0J&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=opIuWAKmywF059tAs2i3Pg&m=B6iFCsmZGjca1mKRVOeoNySiRpWdnEvZLexmRrNkccY&s=w9EL2OW3X1pPPPLi6NV6LmKod124rKXsVKTtakVbZh4&e=>. >>> Also, it might be worth trying your code on a release tag like v3.13.0.2 in >>> case master has a regression. >>> >>> Jonathon >>> >>> On Sat, Oct 20, 2018 at 8:11 AM Samuel Prager via USRP-users < >>> usrp-users@lists.ettus.com> wrote: >>> >>>> Hello, >>>> >>>> I have an RFNoC block that generates command packets to write settings >>>> registers of the downstream connected block using the Control Source >>>> (cmdout_tdata) of the noc_shell . Previously this had worked perfectly >>>> (prior to approximately d6b2283 on rfnoc-devel), for both the X300 and >>>> E310, but this functionality appears to perhaps be broken in the more >>>> recent FPGA releases — since around the switch to Vivado 2017.4 and the >>>> move of the noc block clock domain crossing to axi_wrapper.v). I have tried >>>> the latest master branch (4f25ed1) with no success. >>>> >>>> Is this a known issue? Can anyone shed light on what might have caused >>>> this? >>>> >>>> The control packets are generated in my block as follows: >>>> >>>> *wire eob = 1’b0;* >>>> >>>> *wire [1:0] pkt_type = 2'b10;* >>>> >>>> *wire [11:0] seqnum = 12'd0; // don't care* >>>> >>>> *wire [15:0] payload_length = 16'd16; //don't care (payload length in >>>> bytes)* >>>> >>>> *assign cmd_tdata = {24’d0,set_bus_addr[7:0], set_bus_val[31:0]};* >>>> >>>> *cvita_hdr_encoder cvita_hdr_encoder(* >>>> *.pkt_type(pkt_type),.eob(eob), .has_time(1'b0),* >>>> *.seqnum(seqnum),* >>>> *.payload_length(payload_length),* >>>> *.src_sid(src_sid), .dst_sid(dst_sid),* >>>> *.vita_time(vita_time),* >>>> *.header(cmd_tuser)* >>>> *);* >>>> >>>> *chdr_framer #(.SIZE(FIFO_SIZE), .WIDTH(64)) chdr_framer (* >>>> *.clk(clk), .reset(reset), .clear(clear),* >>>> *.i_tdata(cmd_tdata), .i_tuser(cmd_tuser), .i_tlast(cmd_tlast), >>>> .i_tvalid(cmd_tvalid), .i_tready(cmd_tready),* >>>> *.o_tdata(cmdout_tdata), .o_tlast(cmdout_tlast), >>>> .o_tvalid(cmdout_tvalid), .o_tready(cmdout_tready));* >>>> >>>> The command packets appear to never reach the destination rfnoc block, >>>> but I am at a loss for the cause. >>>> >>>> Is anyone currently using the control source functionality of the >>>> noc_shell? I would really appreciate any pointers on how to fix this. >>>> >>>> Thank you, >>>> >>>> Sam >>>> >>>> _______________________________________________ >>>> USRP-users mailing list >>>> USRP-users@lists.ettus.com >>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.ettus.com_mailman_listinfo_usrp-2Dusers-5Flists.ettus.com&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=opIuWAKmywF059tAs2i3Pg&m=B6iFCsmZGjca1mKRVOeoNySiRpWdnEvZLexmRrNkccY&s=P6_QXK6P9imdGBTvBybF4IrCojJ2jvCDT8CwfAAFlD0&e=> >>>> >>>
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