pci bus rescan from userland

[Ian Lepore]

On Sat, 2018-08-25 at 18:21 +0300, Yuri Pankov wrote:
> Hi,
> 
> Trying to enable the HDMI/DP sound output on NVIDIA Quadro M2200, I have 
> found the following workaround on NVIDIA Linux forums 
> (https://devtalk.nvidia.com/default/topic/1024022/linux/gtx-1060-no-audio-over-hdmi-only-hda-intel-detected-azalia/post/5211273/#5211273):
> 
> setpci -s 01:00.0 0x488.l=0x2000000:0x2000000
> rmmod nvidia-drm nvidia-modeset nvidia
> echo 1 > /sys/bus/pci/devices/0000:01:00.0/remove
> echo 1 > /sys/bus/pci/devices/0000:00:01.0/rescan
> modprobe nvidia-drm
> 
> So far rmmod and modprobe steps are obvious, setpci works as well (I 
> guess I could use pciconf? doesn't really matter).  Is there a FreeBSD 
> equivalent of doing the remove/rescan steps from userland?

devctl(8) has a rescan function.  devinfo(8) might be useful for
figuring out which device(s) to use the rescan command on.

I don't know much about either of these tools beyond the fact that they
exist.

-- Ian