Raspberry Pi 4 PCI Express: It actually works! USB3, SATA... GPUs?
Recently, Tomasz Mloduchowski posted a popular article on his blog detailing the steps he undertook to get access to the hidden PCIe interface of Raspberry Pi 4: the first Raspberry Pi to include PCIe in its design. After seeing his post, and realizing I was meaning to go buy a Raspberry Pi 4, it just seemed natural to try and replicate his results in the hope of taking it a bit further. I am known for Raspberry Pi Butchery, after all.
What follows is a step-by-step guide to how he made it work. Setting up for remote operation, Desoldering the USB3 chip, soldering ultra-fine wires to the exposed pads using a microscope, a few reboot attempts requiring "professional" wiggling of the PCIe slot, hacking the Linux device tree to extend the bus ID limits, and some linux driver hacking, too. The article is filled with pictures and screen caps. He closes out the article listing the devices that were made available (using lspci) and then mentioning:
I also have tried some other fairly hilarious setups, including the following with a Radeon HD 7990 GPU, and another with a GTX 1060.
Even if you are not a hardware or software hacker, the pictures of his efforts along the way, culminating with a huge GPU in a PCI slot attached to a wee little Raspberry Pi 4 are worth the read.
(Score: 2, Interesting) by system32 on Monday October 14 2019, @01:02AM (8 children)
So if this is already possible thanks to the chipsets used, do you think that the Raspberry Pi foundation will make an official release with these features? Even if it cost a little bit more, it would be worth it to those trying to use the 4 as a desktop replacement. The 4 has enough power to actually be a desktop for most users, so why not let those of us doing this have full hardware access? A fully modular Pi, with SATA, PCI slots, and RAM slots would be a game changer for bringing Desktop Linux to the public.
(Score: 4, Informative) by takyon on Monday October 14 2019, @01:09AM (6 children)
I don't think so.
What you will see in the near term is a Compute Module 4 [raspberrypi.org].
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 4, Informative) by takyon on Monday October 14 2019, @01:36AM (5 children)
Raspberry Pi head honcho Eben Upton talks thermals, stores and who's buying the kit [theregister.co.uk]
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 3, Interesting) by opinionated_science on Monday October 14 2019, @01:42AM (4 children)
If I understand correctly, a working PCIe interface, would permit a GPU could be added?
That would be *some* compute upgrade!!
(Score: 2, Informative) by Anonymous Coward on Monday October 14 2019, @02:35AM (3 children)
It has a non-bifurcatable PCIe x4 connector (You need a bridge chip to split out lanes.)
The RK3366 I think it is has had that since the beginning. The Renegade(?) Libre-whatever model is the same chip and may have access too, off an RPi B formfactor board.
Point is: The Pi chips are not the only games in town and there are better groups than the Pi Foundation working on boards on a lot less budget.
And yes, 4GB boards 2 years ago. LPDDR3 and then DDR4
(Score: 2) by coolgopher on Monday October 14 2019, @03:59AM (2 children)
I concur with the parent - the raspberry is not the only choice these days. I'm running more Rock64 boards than raspberry boards these days. Neither is perfect, but I got 4GB RAM years ago, and less hassle in setting up U-Boot. YMMV. The Pi community is certainly a big plus for the raspberries.
(Score: 1, Informative) by Anonymous Coward on Monday October 14 2019, @04:08AM (1 child)
The improvements on Pi4 make it competitive again. The USB and Ethernet changes make a huge difference.
If nothing else, it will drive the others to improve.
(Score: 2) by coolgopher on Monday October 14 2019, @05:19AM
Oh yes, those changes (and RAM!) were well overdue.
(Score: 3, Interesting) by DECbot on Monday October 14 2019, @05:00PM
While I won't hold my breath, I would love to see the PCIe interface exposed in the CM4 boards. That would make a pi4 cluster a lot more attractive.
cats~$ sudo chown -R us /home/base
(Score: 3, Insightful) by Mojibake Tengu on Monday October 14 2019, @02:53AM (1 child)
Gluing a big GPU to Raspi is a crazy idea with questionable practical effects, but there are some other valuable PCIE devices out there, such as true multi serial ports: https://axagon.eu/en/produkty/pcea-s4 [axagon.eu]. Most post-modern cheap USB/Serial bridges are disaster and nightmare.
Respect Authorities. Know your social status. Woke responsibly.
(Score: 2) by coolgopher on Tuesday October 15 2019, @06:09AM
The cp210x series is pretty usable, as long as one keeps track of which port(s) is the full-featured UART and plan your design accordingly.