[coreboot] Thinkpad SD card controller DMA

[Thomasheidler]

Hello,

I noticed that all Lenovo Thinkpads supported by coreboot have a SD card controller that is connected as a PCI device. I assume that the controller runs non-free firmware from its own ROM and because it is a PCI device it should have DMA, which seems like a security risk, right?

If so, is there a way to prevent the SD card controller from turning on when the computer is booted, by changing some code in the source (maybe in devicetree.cb) or at least to stop the controller from having DMA?

Thanks a lot,

Thomas