FROMLIST: drm/msm/dp: add .shutdown to mask HPD IRQ before system shutdown

[yashgupta2126]

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.

Link: https://lore.kernel.org/all/20260717-dpshutdown-v1-1-b062c2f7dfb1@oss.qualcomm.com/

CRs-Fixed: 4573119

[qcomlnxci]

Test jobs on 2d53bf1

• Job 183890 on hamoa-iot-evk
• Job 183888 on lemans-evk
• Job 183886 on monaco-evk
• Job 183891 on qcs615-ride
• Job 183887 on qcs6490-rb3gen2
• Job 183885 on qcs8300-ride
• Job 183889 on qcs9100-ride-r3
• Job on qrb2210-rb1

[qcomlnxci]

Test Matrix

Test Case	hamoa-iot-evk	lemans-evk	monaco-evk	qcs615-ride	qcs6490-rb3gen2	qcs8300-ride	qcs9100-ride-r3
BT_FW_KMD_Service	✅ Pass	✅ Pass	✅ Pass	❌ Fail	✅ Pass	✅ Pass	✅ Pass
BT_ON_OFF	✅ Pass	✅ Pass	✅ Pass	⚠️ skip	✅ Pass	✅ Pass	✅ Pass
BT_SCAN	✅ Pass	✅ Pass	✅ Pass	⚠️ skip	✅ Pass	✅ Pass	✅ Pass
CPUFreq_Validation	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
CPU_affinity	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
DSP_AudioPD	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
Ethernet	⚠️ skip	⚠️ skip	⚠️ skip	⚠️ skip	⚠️ skip	⚠️ skip	⚠️ skip
Freq_Scaling	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
GIC	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
IPA	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
Interrupts	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
OpenCV	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
PCIe	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
Probe_Failure_Check	❌ Fail	❌ Fail	❌ Fail	✅ Pass	❌ Fail	❌ Fail	❌ Fail
RMNET	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
UFS_Validation	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
USBHost	✅ Pass	❌ Fail	❌ Fail	❌ Fail	❌ Fail	❌ Fail	❌ Fail
WiFi_Firmware_Driver	❌ Fail	✅ Pass	❌ Fail	✅ Pass	✅ Pass	✅ Pass	✅ Pass
WiFi_OnOff	❌ Fail	✅ Pass	❌ Fail	⚠️ skip	✅ Pass	✅ Pass	✅ Pass
adsp_remoteproc	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
cdsp_remoteproc	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
gpdsp_remoteproc	⚠️ skip	✅ Pass	✅ Pass	⚠️ skip	⚠️ skip	✅ Pass	✅ Pass
hotplug	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
irq	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
kaslr	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
pinctrl	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
qcom_hwrng	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
remoteproc	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
rngtest	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
shmbridge	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
smmu	❌ Fail	❌ Fail	✅ Pass	❌ Fail	✅ Pass	✅ Pass	❌ Fail
watchdog	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass
wpss_remoteproc	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass	✅ Pass