Hacker Gets The mini-PCIe slot of the Compute Module will power the graphics card; however, not a powerful one.

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Raspberry pi
(Image credit: Toble_Miner)

Raspberry Pi Compute Module 4 carriers that show the board’s slot-free PCIe connection aren’t rare.¬†

The official carrier board has a slot, but the less common are concepts of how you can use the connections. It was probably inevitable that somebody would attempt using a mini-PCIe-based graphics card even though there’s a high-quality GPU on the Pi’s SOC already, and this is precisely what Twitter users¬†Toble_Miner¬†has created.

The card in question is one of the Delock mini-PCIe devices built upon the¬†SM750¬†chipset manufactured by Silicon Motion. It’s made to offer 2D video and graphics to embedded software, thinner clients, as well as servers. It’s unlikely to be on our¬†top graphic cards¬†list anytime shortly. With four cores operating at 300MHz and 100MB of system memory, it is capable of delivering video through a pair of analog VGA connectors and also some more advanced outputs, including Digital LCD Panel Interfaces, as well as Zoomed Video interfaces (used by devices that are connected to PCMCIA slots on laptops).

Toble_Miner’s efforts, which included changing the driver’s settings on the most recent Raspberry Pi OS Bullseye OS release because it was discovered that the “Broadcom PCIe host seems not like writing combining,” caught the attention of the developer and friend of¬†Tom’s Hardware pi Cast Jeff Geerling¬†who maintains an inventory of PCIe devices that are compatible with Compute Module 4¬†on his GitHub page.¬†Geerlingguy revealed that this is¬†in no way the sole SM750¬†card that flashed into life when connected to the small processing board.

Enter the ASRock Rack M2_VGA. A graphics card can fit into the M2 socket, which is usually packed with SSD. It also runs the SM750 chipset, which according to Geerling’s research, isn’t as efficient as the Raspberry Pi’s integrated GPU. After figuring out that M2 cards need external power and then recompiling the kernel, he is stuck and eventually emails ASRock to inform them that the M2 card is designed to be used on Intel servers and, therefore, could not be compatible with the Pi that is based on Arm. Pi.

The entire thread is well worth reading if you’re looking to hack GPU drivers to force cards to function in ways they’re not intended to. A year later, after his first post, Toble_Miner’s article on writing combining appears to be a new reason for Geerling to get involved in the project. So we might be lucky and witness an improvement on Pi graphic cards. It’s all we need is Nvidia to launch an RTX card that comes with a mini PCIe (a single-lane version of PCIe Gen 2, to be precise) interface.