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I just used the Raspberry-PI V to bring up the PCIe interface on a Lattice Certus-Pro NX "Versa" board, it's very convenient. What's cool is that the Raspberry
by jhallenworld 1y ago
I just used the Raspberry-PI V to bring up the PCIe interface on a Lattice Certus-Pro NX "Versa" board, it's very convenient.
What's cool is that the Raspberry-PI V is just fast enough to run modern desktop software, including (ack!) Microsoft Teams. I was able to give a live demo of my FPGA design by sharing the desktop during a conference call.
My only complaint is, of course, lack of SoC documentation from Broadcom.
Say what you will about Intel, but they do provide full chip documentation if you go through their NDA process. With it, I made a very nice FPGA PCIe environment on Xeon Ivy Bridge: it let me save all of the PCI config registers, then reconfigure the FPGA, then reprogram them and have the chip show up on the bus without having to reboot the server or re-enumerate. The trick is to temporarily set the root complex bit to disable PCIe error detection during the reconfiguration process.
(Was using Altera Stratix-IIgx at the time).
There is possibly another way to this, but haven't tried it:
https://stackoverflow.com/questions/32334870/how-to-do-a-true-rescan-of-pcie-bus https://stackoverflow.com/questions/32334870/how-to-do-a-tru...
But even aside from that, with the documentation you have access to a lot of error reporting which is extremely useful during PCIe bring-up.
- akamoonknight 1y agoAh, that's a fancy trick! I remember many a time making Linux real angry with my PCIe fiddling. I believe in the end we got Partial Reconfiguration set up, where the PCIe portion of the device would not be reprogrammed but we could reload the rest. It was definitely a trade off though in terms of layout planning and space reservation.
- eqvinox 1y ago> Say what you will about Intel, but they do provide full chip documentation if you go through their NDA process. Unfortunately, we are unable to support individuals or smaller entities. Please reach out to your local Intel sales office for assistance. Are we talking about the same Intel? (This is the reply I got trying to sign their NDA in order to access datasheets. Even my 15-people employer wasn't worth their time.)
- jhallenworld 1y agoHmm, well the last time I did this was to get information for designing Intel Atom into an embedded system- this was ~2019 (I work for a small design firm). I remember you had to sign up for a premier account, sign a CNDA, then ask them to add the specific chipset documentation to your account. Maybe they were forgiving because these were low-end embedded chips. Anyway, the information for the PCIe registers is in documents like this: https://theretroweb.com/misc/documentation/324642-003-67f43ce1bf9fc324455360.pdf https://theretroweb.com/misc/documentation/324642-003-67f43c...
- eqvinox 1y agoThis was the "sign a CNDA" step. They just refused to give one to sign. The specific case was about Thunderbolt controllers, I guess they fact that they're selling licenses to the Thunderbolt trademark might also be a factor. The datasheets themselves have leaked on Mac forums, but that's not enough to build a design on… …so the alternate option now is ASMedia USB4 chips…