Hi Dave, > Hi Danilo > > > 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. :) > > > > Thanks for the hint. > > That usleep_range(200, 400) is just to give the PCI power transition time to > settle before an immediate kexec jump. > > It’s mirroring the existing nouveau_pmops_suspend() behavior, which already > does udelay(200) right after pci_set_power_state(..., PCI_D3hot). In > ->shutdown() we’re allowed to > sleep, so I used usleep_range() instead of a busy-wait udelay().
Dave, if this is ok, I would add it as comment in the next version. Regards, Li
