Re: [PATCH v10 11/15] drm/atomic-helper: Set fence deadline for vblank

[Dmitry Baryshkov]

On 08/03/2023 17:53, Rob Clark wrote:
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> For an atomic commit updating a single CRTC (ie. a pageflip) calculate
> the next vblank time, and inform the fence(s) of that deadline.
>
> v2: Comment typo fix (danvet)
> v3: If there are multiple CRTCs, consider the time of the soonest vblank
>
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> ---
>   drivers/gpu/drm/drm_atomic_helper.c | 37 +++++++++++++++++++++++++++++
>   1 file changed, 37 insertions(+)

As I started playing with hotplug on RB5 (sm8250, DSI-HDMI bridge), I 
found that this patch introduces the following backtrace on HDMI 
hotplug. Is there anything that I can do to debug/fix the issue? The 
warning seems harmless, but it would be probably be good to still fix 
it. With addresses decoded:

[   31.151348] ------------[ cut here ]------------
[   31.157043] msm_dpu ae01000.display-controller: 
drm_WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev))
[   31.157177] WARNING: CPU: 0 PID: 13 at 
drivers/gpu/drm/drm_vblank.c:728 
drm_crtc_vblank_helper_get_vblank_timestamp_internal 
(drivers/gpu/drm/drm_vblank.c:728)
[   31.180629] Modules linked in:
[   31.184106] CPU: 0 PID: 13 Comm: kworker/0:1 Not tainted 
6.3.0-rc2-00008-gd39e48ca80c0 #542
[   31.193358] Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
[   31.200796] Workqueue: events lt9611uxc_hpd_work
[   31.205990] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS 
BTYPE=--)
[   31.213722] pc : drm_crtc_vblank_helper_get_vblank_timestamp_internal 
(drivers/gpu/drm/drm_vblank.c:728)
[   31.222032] lr : drm_crtc_vblank_helper_get_vblank_timestamp_internal 
(drivers/gpu/drm/drm_vblank.c:728)
[   31.230341] sp : ffff8000080bb8d0
[   31.234061] x29: ffff8000080bb900 x28: 0000000000000038 x27: 
ffff61a7956b8d60
[   31.242051] x26: 0000000000000000 x25: 0000000000000000 x24: 
ffff8000080bb9c4
[   31.250038] x23: 0000000000000001 x22: ffffbf0033b94ef0 x21: 
ffff61a7957901d0
[   31.258029] x20: ffff61a795710000 x19: ffff61a78128b000 x18: 
fffffffffffec278
[   31.266014] x17: 0040000000000465 x16: 0000000000000020 x15: 
0000000000000060
[   31.274001] x14: 0000000000000001 x13: ffffbf00354550e0 x12: 
0000000000000825
[   31.281989] x11: 00000000000002b7 x10: ffffbf00354b1208 x9 : 
ffffbf00354550e0
[   31.289976] x8 : 00000000ffffefff x7 : ffffbf00354ad0e0 x6 : 
00000000000002b7
[   31.297963] x5 : ffff61a8feebbe48 x4 : 40000000fffff2b7 x3 : 
ffffa2a8c9f64000
[   31.305947] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 
ffff61a780283100
[   31.313934] Call trace:
[   31.316719] drm_crtc_vblank_helper_get_vblank_timestamp_internal 
(drivers/gpu/drm/drm_vblank.c:728)
[   31.324646] drm_crtc_vblank_helper_get_vblank_timestamp 
(drivers/gpu/drm/drm_vblank.c:843)
[   31.331528] drm_crtc_get_last_vbltimestamp 
(drivers/gpu/drm/drm_vblank.c:884)
[   31.337170] drm_crtc_next_vblank_start 
(drivers/gpu/drm/drm_vblank.c:1006)
[   31.342430] drm_atomic_helper_wait_for_fences 
(drivers/gpu/drm/drm_atomic_helper.c:1531 
drivers/gpu/drm/drm_atomic_helper.c:1578)
[   31.348561] drm_atomic_helper_commit 
(drivers/gpu/drm/drm_atomic_helper.c:2007)
[   31.353724] drm_atomic_commit (drivers/gpu/drm/drm_atomic.c:1444)
[   31.358127] drm_client_modeset_commit_atomic 
(drivers/gpu/drm/drm_client_modeset.c:1045)
[   31.364146] drm_client_modeset_commit_locked 
(drivers/gpu/drm/drm_client_modeset.c:1148)
[   31.370071] drm_client_modeset_commit 
(drivers/gpu/drm/drm_client_modeset.c:1174)
[   31.375233] drm_fb_helper_set_par 
(drivers/gpu/drm/drm_fb_helper.c:254 drivers/gpu/drm/drm_fb_helper.c:229 
drivers/gpu/drm/drm_fb_helper.c:1644)
[   31.380108] drm_fb_helper_hotplug_event 
(drivers/gpu/drm/drm_fb_helper.c:2302 (discriminator 4))
[   31.385456] drm_fb_helper_output_poll_changed 
(drivers/gpu/drm/drm_fb_helper.c:2331)
[   31.391376] drm_kms_helper_hotplug_event 
(drivers/gpu/drm/drm_probe_helper.c:697)
[   31.396825] drm_bridge_connector_hpd_cb 
(drivers/gpu/drm/drm_bridge_connector.c:129)
[   31.402175] drm_bridge_hpd_notify (drivers/gpu/drm/drm_bridge.c:1315)
[   31.406954] lt9611uxc_hpd_work 
(drivers/gpu/drm/bridge/lontium-lt9611uxc.c:185)
[   31.411450] process_one_work (kernel/workqueue.c:2395)
[   31.415949] worker_thread (include/linux/list.h:292 
kernel/workqueue.c:2538)
[   31.426843] kthread (kernel/kthread.c:376)
[   31.437182] ret_from_fork (arch/arm64/kernel/entry.S:871)
[   31.447828] irq event stamp: 44642
[   31.458284] hardirqs last enabled at (44641): __up_console_sem 
(arch/arm64/include/asm/irqflags.h:182 (discriminator 1) 
arch/arm64/include/asm/irqflags.h:202 (discriminator 1) 
kernel/printk/printk.c:345 (discriminator 1))
[   31.474540] hardirqs last disabled at (44642): el1_dbg 
(arch/arm64/kernel/entry-common.c:335 arch/arm64/kernel/entry-common.c:406)
[   31.489882] softirqs last enabled at (42912): _stext 
(arch/arm64/include/asm/current.h:19 arch/arm64/include/asm/preempt.h:13 
kernel/softirq.c:415 kernel/softirq.c:600)
[   31.505256] softirqs last disabled at (42907): ____do_softirq 
(arch/arm64/kernel/irq.c:81)
[   31.521139] ---[ end trace 0000000000000000 ]---



--
With best wishes
Dmitry