[dhon_]

In this case though, the new driver has the same license as the project it was based on and explicitly credits the original project

  ISC License
  
  Copyright (c) 2010-2022 Broadcom Corporation
  Copyright (c) brcmfmac-freebsd contributors
  
  Based on the Linux brcmfmac driver.

[josephg]

This surprised me - but sure enough, they're right. The linux brcmfmac driver is ISC licensed:

https://github.com/torvalds/linux/blob/master/drivers/net/wi...

// SPDX-License-Identifier: ISC

[emaste]

A lot of Linux kernel drivers are permissively licensed, or dual-licensed with a choice of GPL and a permissive license. This is especially common for vendor-developed drivers. From a hardware vendor’s perspective, broad license compatibility directly supports adoption: the more operating systems, hypervisors, and embedded environments that can incorporate the driver code, the wider the potential market for the hardware itself.