On Fri, Jul 17, 2026 at 04:56:13PM +0530, Mahadevan P wrote: > On reboot, a late DP hot-plug-detect (HPD) IRQ can fire after > apps_smmu has already disabled translation for the display > subsystem, causing the HPD thread to kick off a new modeset that > drives DPU/DP hardware and DMA through a stale IOMMU mapping. > > DPU's own .shutdown disables all CRTCs first, but a pending HPD IRQ > thread wakes up afterwards, reads the DPCD, and fires an unsolicited > hotplug event that triggers a second atomic commit turning the > display back on -- right as the IOMMU is disabling translation: > > systemd-shutdown[1]: Rebooting. > msm_dpu: drm_atomic_commit: committing (shutdown disabling CRTCs) > arm-smmu 3da0000.iommu: disabling translation > msm_dpu: drm_dp_read_dpcd_caps (late HPD IRQ thread wakes up) > msm_dpu: drm_sysfs_connector_hotplug_event: DP-1 hotplug event > msm_dpu: drm_client_modeset_probe: DP-1 found preferred mode > msm_dpu: drm_atomic_commit: committing (unsolicited, re-enables display) > dpu_crtc_commit_kickoff: crtc94 first commit > arm-smmu 15200000.iommu: disabling translation > > Mask and flush the IRQ in .shutdown so no HPD event can retrigger a > modeset once shutdown has started. > Reported on lemans-evk and monaco-evk during reboot stress testing. > > Assisted-by: Claude:claude-sonnet-5 > Signed-off-by: Mahadevan P <[email protected]> > --- > drivers/gpu/drm/msm/dp/dp_display.c | 9 +++++++++ > 1 file changed, 9 insertions(+)
I'd very much prefer if instead we fix the framework to stop polling and HPD notifications on shutdown. -- With best wishes Dmitry
