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(). Regards, Li
