> I feel like this issue is to at least some extent a red herring.

I don't see that, these two issues adequately explain why so few GPUs have official support. They don't want to get hit with a lawsuit, as a result of issues outside their sphere of control.

> If this really is due to patent issues AMD can likely afford to license or cross-license the patent given potential upside.

Have you ever known any company willing to cede market dominance and license or cross-license a patent letting competition into a market that they hold an absolute monopoly over, let alone in an environment where antitrust is non-existent and fang-less?

There is no upside for NVIDIA to do that. If you want to do serious AI/ML work you currently need to use NVIDIA hardware, and they can charge whatever they want for that.

The moment you have a competitor, demand is halved at a bare minimum depending on how much the competitor undercuts you by. Any agreement on coordinating prices leads to price-fixing indictments.

> I don't see that, these two issues adequately explain why so few GPUs have official support.

I'm sorry I don't follow this. Surely if all AMD GPUs have the same problem with atomics then this can't explain why some GPUs are supported and others aren't?

> There is no upside for NVIDIA to do that.

If NVIDIA felt this patent was actually protecting them from competition then there would be no upside. But NVIDIA has competiton from AMD, Intel, Google, and Amazon. Intel have managed to engineer OneAPI support for their GPUs without licensing this patent or relying on PCIe atomics.

AMD have patents NVIDIA would be interested in. For example multi-chiplet GPUs.