Re: [PATCH] nouveau: pci: quiesce GPU on shutdown

[Danilo Krummrich]

On Wed Jan 21, 2026 at 1:50 AM CET, Li Chen wrote:
>  > > +       usleep_range(200, 400);\
>  > 
>  > Why is this needed? it at least needs a comment.
>
> This patch is needed for kexec/KHO/LUO reboot: firmware reset is skipped, so the GPU may remain in an active/DMA 
> state and the next kernel can fail to re-init nouveau. We can’t call the full DRM/TTM teardown from ->shutdown() because
> userspace may still hold DRM fds during shutdown, which triggers WARNs.
>
> So the shutdown hook reuses the suspend/quiesce path (safe with open fds) and then powers down the PCI function (D3hot)
> to leave the device in a consistent state for the next kernel.

I think the question was about the usleep_range() specifically. :)