Qualcomm MHI Host Controller for PCIe Cellular Modems
The host side of the Modem Host Interface, the protocol Qualcomm-based PCIe and M.2 cellular modems use to talk to a Linux machine. It's what lets laptops, routers, and IoT gateways drive 4G/5G modules from vendors like Sierra Wireless, Telit, Quectel, Foxconn, and Cinterion, including current 5G products such as the Sierra EM9191 and Telit FN990B40.
recommendation
It should stay because the hardware it supports — Qualcomm-based 5G M.2 modems — is actively sold in 2025 and widely deployed in laptops, industrial gateways, and routers. Upstream development is healthy, with a major init.c rework and a new PF/VF controller-configuration series both landing in 2025, and new modem PCI IDs continue to be added. There is no sign of deprecation.
repository signals
sources
- kernel.org
MHI is an active Linux bus/protocol primarily used by host processors to control and communicate with modem devices, especially PCIe-based devices.
- lore-kernel.gnuweeb.org
drivers/bus/mhi/host saw substantive upstream design discussion and code changes in 2025, including a large init.c rework for MHI control configuration allocation.
- spinics.net
A 2025 patch series added PF/VF split controller configuration support to bus: mhi: host, showing ongoing feature development rather than deprecation.
- sierrawireless.com
Sierra Wireless markets the EM9191 5G M.2 module, one class of hardware supported by this driver family, indicating new-deployment relevance.
- telit.com
Telit markets the FN990B40 5G M.2 modem, another supported modem class, indicating hardware is still sold for current deployments.
codex reasoning notes (technical)
Local inspection via exec_command of Kconfig and pci_generic.c shows this is the MHI host/controller driver, not a helper library, with live PCI IDs for Quectel/Sierra/Telit/Foxconn/Cinterion devices. Upstream attention was checked first using web search/open on lore/archive results: the 2025 lore thread on init.c and the 2025 PF/VF patch series show active maintenance and new functionality; I found no removal/deprecation thread in the performed lore-targeted searches. Deployment evidence came from vendor product pages obtained by web search/open for Sierra EM9191 and Telit FN990B40, both current M.2 cellular modem products matching hardware families enumerated in pci_generic.c. Because the directory is young, heavily touched recently, and still gaining modem IDs/features for currently sold hardware, the defensible recommendation is keep.