[PATCH] Revert "drm/xe/display: use xe->display to decide whether to do anything"

[Kasireddy, Vivek]

Hi Jani,

> Subject: Re: [PATCH] Revert "drm/xe/display: use xe->display to decide
> whether to do anything"
> 
> On Thu, 05 Jun 2025, Jani Nikula <jani.nikula at intel.com> wrote:
> > On Wed, 04 Jun 2025, Vivek Kasireddy <vivek.kasireddy at intel.com> wrote:
> >> This reverts commit 5a9f299f956ef9764f56044cfca7aafa23cea1d1.
> >>
> >> The following crash/regression was seen with the reverted commit
> >> on a specific BMG SKU with no display capabilities:
> >>
> >> [  115.582833] BUG: kernel NULL pointer dereference, address:
> 00000000000005d0
> >> [  115.589775] #PF: supervisor write access in kernel mode
> >> [  115.594976] #PF: error_code(0x0002) - not-present page
> >> [  115.600088] PGD 0 P4D 0
> >> [  115.602617] Oops: Oops: 0002 [#1] SMP
> >> [  115.606267] CPU: 14 UID: 0 PID: 1547 Comm: kworker/14:3 Tainted: G
> 	U      E       6.15.0-local+ #62 PREEMPT(voluntary)
> >> [  115.617332] Tainted: [U]=USER, [E]=UNSIGNED_MODULE
> >> [  115.622100] Hardware name: Intel Corporation Meteor Lake Client
> Platform/MTL-P DDR5 SODIMM SBS RVP, BIOS
> MTLPEMI1.R00.3471.D49.2401260852 01/26/2024
> >> [  115.635314] Workqueue: pm pm_runtime_work
> >> [  115.639309] RIP: 0010:_raw_spin_lock+0x17/0x30
> >> [  115.662382] RSP: 0018:ffffd13f82e7bc30 EFLAGS: 00010246
> >> [  115.667581] RAX: 0000000000000000 RBX: ffff8be919076000 RCX:
> 0000000000000002
> >> [  115.674675] RDX: 0000000000000001 RSI: 000000000000004b RDI:
> 00000000000005d0
> >> [  115.681775] RBP: ffffd13f82e7bc60 R08: ffffd13f82e7bb00 R09:
> ffff8beb0c1b06c0
> >> [  115.688869] R10: ffff8be7c034f4c0 R11: fefefefefefefeff R12: fffffffffffffff0
> >> [  115.695965] R13: ffff8be9190762e8 R14: ffff8be919077798 R15:
> 00000000000005d0
> >> [  115.703062] FS:  0000000000000000(0000) GS:ffff8beb552b6000(0000)
> knlGS:0000000000000000
> >> [  115.711106] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >> [  115.716826] CR2: 00000000000005d0 CR3: 000000024c68d002 CR4:
> 0000000000f72ef0
> >> [  115.723921] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> >> [  115.731015] DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7:
> 0000000000000400
> >> [  115.738113] PKRU: 55555554
> >> [  115.740816] Call Trace:
> >> [  115.743258]  <TASK>
> >> [  115.745363]  ? xe_display_flush_cleanup_work+0x92/0x120 [xe]
> >> [  115.751102]  xe_display_pm_runtime_suspend+0x42/0x80 [xe]
> >> [  115.756542]  xe_pm_runtime_suspend+0x11b/0x1b0 [xe]
> >> [  115.761463]  xe_pci_runtime_suspend+0x23/0xd0 [xe]
> >> [  115.766291]  pci_pm_runtime_suspend+0x6b/0x1a0
> >> [  115.770717]  ? pci_pm_thaw_noirq+0xa0/0xa0
> >> [  115.774797]  __rpm_callback+0x48/0x1e0
> >> [  115.778531]  ? pci_pm_thaw_noirq+0xa0/0xa0
> >> [  115.782614]  rpm_callback+0x66/0x70
> >> [  115.786090]  ? pci_pm_thaw_noirq+0xa0/0xa0
> >> [  115.790173]  rpm_suspend+0xe1/0x5e0
> >> [  115.793647]  ? psi_task_switch+0xb8/0x200
> >> [  115.797643]  ? finish_task_switch.isra.0+0x8d/0x270
> >> [  115.802502]  pm_runtime_work+0xa6/0xc0
> >> [  115.806238]  process_one_work+0x186/0x350
> >> [  115.810234]  worker_thread+0x33a/0x480
> >> [  115.813968]  ? process_one_work+0x350/0x350
> >> [  115.818132]  kthread+0x10c/0x220
> >> [  115.821350]  ? kthreads_online_cpu+0x120/0x120
> >> [  115.825774]  ret_from_fork+0x3a/0x60
> >> [  115.829339]  ? kthreads_online_cpu+0x120/0x120
> >> [  115.833768]  ret_from_fork_asm+0x11/0x20
> >> [  115.829339]  ? kthreads_online_cpu+0x120/0x120
> >> [  115.833768]  ret_from_fork_asm+0x11/0x20
> >> [  115.837680]  </TASK>
> >> [  115.839907]  acpi_tad(E) drm(E)
> >> [  115.931629] CR2: 00000000000005d0
> >> [  115.934935] ---[ end trace 0000000000000000 ]---
> >> [  115.939531] RIP: 0010:_raw_spin_lock+0x17/0x30
> >>
> >> We cannot yet use xe->display to determine whether display hardware
> >> has been successfully probed/initialized or not. This is because
> >> xe->display would not be set to NULL even with GPUs with no display
> >> capabilities (e.g, GMD_ID_DISPLAY = 0). However, this might change
> >> in the future as Xe and i915 code is unified to deal with no display
> >> cases.
> >>
> >> Therefore, for now we have to continue to rely on xe->info.probe_display
> >> (which would be set to false with display-less GPUs) to decide
> >> whether to invoke any display related functions or not.
> >>
> >> Cc: Jani Nikula <jani.nikula at intel.com>
> >> Cc: Matt Roper <matthew.d.roper at intel.com>
> >> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> >> Signed-off-by: Vivek Kasireddy <vivek.kasireddy at intel.com>
> >
> > Thanks, and sorry again for the trouble,
> >
> > Reviewed-by: Jani Nikula <jani.nikula at intel.com>
> 
> Are you going to merge this? I think it needs to be merged via
> drm-intel-next, that's where the original changes are.
I do not have commit access to drm-intel-next. So, I guess either you
or Matt would need to merge it. 

Thanks,
Vivek

> 
> BR,
> Jani.
> 
> 
> --
> Jani Nikula, Intel