litex produces non-functional bitfile for digilent cmod a7 35t with symbiflow

[bl0x]

What is observed:

• A compiled litex bitfile for CMOD A7 35t using symbiflow toolchain does not work
  • LED chaser does not blink the LEDs
  • logging in via lxterm is not possible
• On the other hand, a bitfile compiled with Vivado works just as expected

What is expected:

• The bitfile should work also when compiled using symbiflow toolchain

Prerequisites:

• Symbiflow is installed according to the instructions on the web
• I'm using this to set up my environment:

export INSTALL_DIR=~/opt/symbiflow
export FPGA_FAM="xc7"
export PATH="$INSTALL_DIR/$FPGA_FAM/install/bin:$PATH";
source "$INSTALL_DIR/$FPGA_FAM/conda/etc/profile.d/conda.sh"
conda activate $FPGA_FAM

• Litex is installed according to the quick start guide

Steps to reproduce:

• Build litex

cd /base/dir/of/litex
python -m litex_boards.targets.digilent_cmod_a7 --toolchain symbiflow --build

• Upload resulting bitfile to CMOD A7 module with openOCD

openocd -f digilent_cmod_a7.cfg -c "init; pld load 0 digilent_cmod_a7.bit; exit;"

Versions:

yosys:
Yosys 0.9+4270 (git sha1 539d4ee9, x86_64-conda_cos6-linux-gnu-gcc 1.24.0.133_b0863d8_dirty -fvisibility-inlines-hidden -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -ffunction-sections -fdebug-prefix-map=/home/runner/work/conda-eda/conda-eda/workdir/conda-env/conda-bld/yosys_1628927583200/work=/usr/local/src/conda/yosys-0.9_5567_g539d4ee9 -fdebug-prefix-map=/home/bloeher/opt/symbiflow/xc7/conda/envs/xc7=/usr/local/src/conda-prefix -fPIC -Os -fno-merge-constants)

vpr:
VPR FPGA Placement and Routing.
Version: 8.1.0-dev+06317d042
Revision: 8.0.0-4118-g06317d042
Compiled: 2021-08-13T07:42:12
Compiler: GNU 9.3.0 on Linux-4.15.0-1113-azure x86_64
Build Info: Release IPO PGO VTR_ASSERT_LEVEL=2

symbiflow-arch-defs:
Version: 20211116-000105

litex (installed on 20220117):
$for d in lite* migen; do [[ -d $d ]] && (echo -n "$d: "; git -C $d log --pretty=format:"%h%x09%an%x09%ad%x09%s" | head -n1) ; done |sort
litedram: 24fad45       Florent Kermarrec       Mon Jan 17 10:56:09 2022 +0100  frontend/dma/LiteDRAMDMAReader: Make sure to flush FIFO/Reservation counter when disabled.
liteeth: 14edaae        Florent Kermarrec       Fri Jan 14 18:38:21 2022 +0100  frontend/stream: Add data_width support.
litehyperbus: a950fa7   Florent Kermarrec       Wed Jan 5 09:03:33 2022 +0100   Bump year.
liteiclink: 7718e96     Florent Kermarrec       Wed Jan 5 09:04:25 2022 +0100   Bump year.
litejesd204b: 0c90b3e   Florent Kermarrec       Wed Jan 5 09:05:09 2022 +0100   Bump year.
litepcie: 5446109       Florent Kermarrec       Thu Jan 13 18:01:35 2022 +0100  tlp/(de)packetizer: Cosmetic cleanup.
litesata: c068dc8       Florent Kermarrec       Wed Jan 5 09:06:39 2022 +0100   Bump year.
litescope: 42a3577      Florent Kermarrec       Wed Jan 5 09:24:43 2022 +0100   ci: Install ninja-build/meson.
litesdcard: e52c731     Florent Kermarrec       Wed Jan 5 09:07:52 2022 +0100   Bump year.
litespi: 4a8e149        Florent Kermarrec       Wed Jan 5 09:08:36 2022 +0100   Bump year.
litex-boards: b8aad4b   enjoy-digital   Fri Jan 21 08:05:22 2022 +0100  Merge pull request #332 from tcal-x/prog-cmod-a7
litex: 443faef3 Florent Kermarrec       Fri Jan 21 10:05:07 2022 +0100  litex_sim: Update SPI Flash support.
migen: ac70301  Harry Ho        Mon Sep 6 15:08:05 2021 +0800   sayma_amc2: add SSP1 pins

[bl0x]

I've tried the same build with litex and symbiflow environment set up by CFU-playground.

This works!

Versions used in CFU-playground

yosys:
Yosys 0.13+3 (git sha1 61324cf55, x86_64-conda_cos6-linux-gnu-gcc 1.24.0.133_b0863d8_dirty -fvisibility-inlines-hidden -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -ffunction-sections -fdebug-prefix-map=/home/runner/work/conda-eda/conda-eda/workdir/conda-env/conda-bld/yosys_1642201854658/work=/usr/local/src/conda/yosys-0.13_4_g61324cf55 -fdebug-prefix-map=/d/land6/bloeher/CFU-Playground/env/conda/envs/cfu-common=/usr/local/src/conda-prefix -fPIC -Os -fno-merge-constants)

vpr:
VPR FPGA Placement and Routing.
Version: 8.1.0-dev+116f30cb8
Revision: 8.0.0-5105-g116f30cb8
Compiled: 2022-01-14T23:42:34
Compiler: GNU 9.3.0 on Linux-5.11.0-1025-azure x86_64
Build Info: Release IPO PGO VTR_ASSERT_LEVEL=2

symbiflow-arch-defs:
version: 20211222-000718

litex:
$ for d in lite* migen nmigen; do echo -n "$d: "; git -C $d log --pretty=format:"%h%x09%an%x09%ad%x09%s" | head -n1 ; done |sort
litedram: 17c19de       Florent Kermarrec Mon Nov 29 13:22:11 2021 +0100        frontend/dma: Move ack of write responses and other cosmetic cleanups.
liteeth: 7acb2a8        enjoy-digital Sun Nov 21 21:19:17 2021 +0100    Merge pull request #96 from lschuermann/dev/compliant-xgmii-fixup
litehyperbus: 9f118e8   Florent Kermarrec Tue Aug 31 17:50:01 2021 +0200        Copyrights: Bump year.
liteiclink: 3d8ecdb     Florent Kermarrec Thu Apr 1 18:59:33 2021 +0200 serdes/gtx_7series: Set TXDIFFCTRL default control value also to 0b1000 (800mV).
litepcie: 90013df       enjoy-digital Tue Nov 30 09:47:42 2021 +0100    Merge pull request #66 from JuliaComputing/tb/pr1
litescope: 08072a7      Florent Kermarrec Tue Aug 31 17:48:07 2021 +0200        Copyrights: Bump year.
litespi: 05afb0c        enjoy-digital Sun Oct 24 10:09:15 2021 +0200    Merge pull request #64 from gregdavill/generic_phy_x1_fix
litevideo: 41f3014      Florent Kermarrec Sat Apr 11 19:54:42 2020 +0200        README: switch to markdown.
litex: d36e1b60 enjoy-digital Tue Dec 21 19:22:01 2021 +0100    Merge pull request #1139 from tilk/jtagbone_typo
litex_boards: b8aad4b   enjoy-digital Fri Jan 21 08:05:22 2022 +0100    Merge pull request #332 from tcal-x/prog-cmod-a7
migen: 9a0be7a  occheung  Fri Nov 12 14:04:01 2021 +0800 kasli v2: enable ExploreWithRemap
nmigen: 0b28a97 whitequark Fri Oct 8 17:48:00 2021 +0000 CI: preserve YoWASP cache as well.

[tcal-x]

@bl0x I seem to have reproduced what you saw. Using the SymbiFlow install from symbiflow-examples, then using litex_boards/targets/digilent_cmod_a7.py, the generated bitstream does not seem to work on the CMOD A7 board. The LEDchaser is not working, and there is no response on ttyUSB1.

[bl0x]

Updating yosys to 0.13 and arch-defs to the 20211222 version allows to produce a working bitfile. The main change was to unpin the versions in xc7/environment.yml and run a conda update.

[mithro]

FYI - @acomodi / @kgugala

[acomodi]

@bl0x @tcal-x Great to hear that it works. The CMOD A7 should be on the way so I can test on HW as well.

I am not sure though what might have changed in the tools and arch-defs that fixed the issue, so I thing that we might still need to investigate what is going on to have a clearer picture.

[tcal-x]

@acomodi -- have you received your CMOD A7 yet? :)

[acomodi]

@tcal-x Yep, actually it has arrived, I am gonna give it a try tomorrow probably

[md-raz]

Hi All,

I was wondering if there was any progress/fix for this, as I ran into a similar issue: I am running the litex_sata_demo example on the Nexys Video Board. All parts of the flow execute without errors, and I get the top.bit file within \build\nexys_video folder. Loading the bit file via Vivado hardware manager and openFPGALoader, the bit file is loaded into the flash but with no response from the FPGA over UART or via the LEDs.

Furthermore, I tried the same flow with the counter example on the Nexys Video board, and also see no response from the LEDs.

To install F4PGA, I used this guide: https://f4pga-examples.readthedocs.io/en/latest/getting.html The examples are from here: https://github.com/chipsalliance/f4pga-examples/tree/main/xc7/litex_sata_demo

I appreciate any help. Thanks!