> -----Original Message-----
> From: Intel-gfx <[email protected]> On Behalf Of Maarten
> Lankhorst
> Sent: Wednesday, January 21, 2026 7:23 PM
> To: [email protected]; [email protected]
> Cc: Maarten Lankhorst <[email protected]>
> Subject: [i915-rt v5 02/21] drm/i915/display: Make get_vblank_counter use
> intel_de_read_fw()
>
> Fixes the following lockdep splat on PREEMPT_RT:
> <3> BUG: sleeping function called from invalid context at
> kernel/locking/spinlock_rt.c:48 <3> in_atomic(): 1, irqs_disabled(): 0,
> non_block:
> 0, pid: 1373, name: xe_module_load <3> preempt_count: 1, expected: 0 <3> RCU
> nest depth: 0, expected: 0 <4> 11 locks held by xe_module_load/1373:
> <4> #0: ffff888107b691a0 (&dev->mutex){....}-{3:3}, at:
> __driver_attach+0x104/0x220 <4> #1: ffff88813cd30280 (&dev-
> >clientlist_mutex){+.+.}-{3:3}, at: drm_client_register+0x32/0xe0 <4> #2:
> ffffffff837f88f8 (registration_lock){+.+.}-{3:3}, at:
> register_framebuffer+0x1b/0x50
> <4> #3: ffffffff835985e0 (console_lock){+.+.}-{0:0}, at:
> fbcon_fb_registered+0x6f/0x90 <4> #4: ffff88812589e6a0 (&helper->lock){+.+.}-
> {3:3}, at: __drm_fb_helper_restore_fbdev_mode_unlocked+0x7b/0x110
> <4> #5: ffff88813cd30158 (&dev->master_mutex){+.+.}-{3:3}, at:
> drm_master_internal_acquire+0x20/0x50
> <4> #6: ffff88812589e488 (&client->modeset_mutex){+.+.}-{3:3}, at:
> drm_client_modeset_commit_locked+0x2a/0x1b0
> <4> #7: ffffc9000031eef0 (crtc_ww_class_acquire){+.+.}-{0:0}, at:
> drm_client_modeset_commit_atomic+0x4c/0x2b0
> <4> #8: ffffc9000031ef18 (crtc_ww_class_mutex){+.+.}-{3:3}, at:
> drm_client_modeset_commit_atomic+0x4c/0x2b0
> <4> #9: ffff888114f7b8b8 (&intel_dp->psr.lock){+.+.}-{3:3}, at:
> intel_psr_lock+0xc5/0xf0 [xe] <4> #10: ffff88812a0cbbc0
> (&wl->lock){+.+.}-{2:2},
> at: intel_dmc_wl_get+0x3c/0x140 [xe]
>
> This splat will happen otherwise on all tracepoints too, for similar reasons.
>
> Signed-off-by: Maarten Lankhorst <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_vblank.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c
> b/drivers/gpu/drm/i915/display/intel_vblank.c
> index 1b7cfe226ff8f..a85796f9d29ba 100644
> --- a/drivers/gpu/drm/i915/display/intel_vblank.c
> +++ b/drivers/gpu/drm/i915/display/intel_vblank.c
> @@ -132,7 +132,7 @@ u32 g4x_get_vblank_counter(struct drm_crtc *crtc)
> if (!vblank->max_vblank_count)
> return 0;
>
> - return intel_de_read(display, PIPE_FRMCOUNT_G4X(display, pipe));
> + return intel_de_read_fw(display, PIPE_FRMCOUNT_G4X(display, pipe));
Looks good to me. However, I think it will be good to limit this to RT.
Just to contain the impact and plan a soft landing.
Regards,
Uma Shankar
> }
>
> static u32 intel_crtc_scanlines_since_frame_timestamp(struct intel_crtc
> *crtc)
> --
> 2.51.0
