Warning at drivers/gpu/drm/drm_atomic_helper.c

[Fabio Estevam]

Hi,

Stopping kmscube application on mx6q through CTRL + C sometimes leads
to the following kernel warning:

^C[ 3939.785516] ------------[ cut here ]------------
[ 3939.790313] WARNING: CPU: 1 PID: 67 at
drivers/gpu/drm/drm_atomic_helper.c:1032
drm_atomic_helper_wait_for_fences+0xe4/0x104
[ 3939.801626] Modules linked in:
[ 3939.804762] CPU: 1 PID: 67 Comm: kworker/1:1 Tainted: G        W
   4.9.4 #1
[ 3939.812094] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 3939.818666] Workqueue: events drm_mode_rmfb_work_fn
[ 3939.823584] Backtrace:
[ 3939.826100] [<c010c3e4>] (dump_backtrace) from [<c010c68c>]
(show_stack+0x18/0x1c)
[ 3939.833689]  r7:ee8aa000 r6:60000013 r5:00000000 r4:c0e25cac
[ 3939.839367] [<c010c674>] (show_stack) from [<c03f67dc>]
(dump_stack+0xb4/0xe8)
[ 3939.846604] [<c03f6728>] (dump_stack) from [<c0124bb8>] (__warn+0xd8/0x104)
[ 3939.853578]  r10:ee577b80 r9:c04c9f3c r8:00000408 r7:00000009
r6:c0c3c438 r5:00000000
[ 3939.861414]  r4:00000000 r3:00000000
[ 3939.865001] [<c0124ae0>] (__warn) from [<c0124c98>]
(warn_slowpath_null+0x28/0x30)
[ 3939.872581]  r9:00000000 r8:00000000 r7:00000001 r6:ee577b80
r5:00000000 r4:ef101800
[ 3939.880340] [<c0124c70>] (warn_slowpath_null) from [<c04c9f3c>]
(drm_atomic_helper_wait_for_fences+0xe4/0x104)
[ 3939.890356] [<c04c9e58>] (drm_atomic_helper_wait_for_fences) from
[<c04cc754>] (drm_atomic_helper_commit+0x8c/0xe8)
[ 3939.900802]  r9:00000000 r8:ee8b1c8c r7:ee8b1800 r6:00000000
r5:00000000 r4:ee577b80
[ 3939.908562] [<c04cc6c8>] (drm_atomic_helper_commit) from
[<c04f517c>] (imx_drm_atomic_commit+0x1fc/0x340)
[ 3939.918137]  r7:ee8aec18 r6:00000000 r5:ee577b80 r4:00000006
[ 3939.923813] [<c04f4f80>] (imx_drm_atomic_commit) from [<c04ebee0>]
(drm_atomic_commit+0x54/0x60)
[ 3939.932609]  r10:00000001 r9:00000000 r8:ee8b1c8c r7:ee8aec18
r6:ee8b1800 r5:ee577b80
[ 3939.940444]  r4:00000000
[ 3939.942994] [<c04ebe8c>] (drm_atomic_commit) from [<c04ccca4>]
(drm_atomic_helper_set_config+0x80/0xa4)
[ 3939.952395]  r7:ee8aec18 r6:ee8abe2c r5:00000000 r4:ee577b80
[ 3939.958068] [<c04ccc24>] (drm_atomic_helper_set_config) from
[<c04de8e4>] (drm_mode_set_config_internal+0x6c/0xfc)
[ 3939.968424]  r7:ee8b1800 r6:ee8b1c80 r5:ee8aec18 r4:00000000
[ 3939.974095] [<c04de878>] (drm_mode_set_config_internal) from
[<c04de9ac>] (drm_crtc_force_disable+0x38/0x40)
[ 3939.983930]  r7:ee8b1800 r6:ee8b1c80 r5:ee4869c0 r4:ee8aec18
[ 3939.989603] [<c04de974>] (drm_crtc_force_disable) from [<c04ed768>]
(drm_framebuffer_remove+0xc8/0x104)
[ 3939.999011] [<c04ed6a0>] (drm_framebuffer_remove) from [<c04ed7e4>]
(drm_mode_rmfb_work_fn+0x40/0x50)
[ 3940.008240]  r9:00000000 r8:ee8abeb0 r7:ef7b4e00 r6:ef7b1800
r5:ee4d5d58 r4:ee4d5d38
[ 3940.016008] [<c04ed7a4>] (drm_mode_rmfb_work_fn) from [<c013ff5c>]
(process_one_work+0x198/0x4e0)
[ 3940.024888]  r5:ef0f4180 r4:ee4d5d38
[ 3940.028478] [<c013fdc4>] (process_one_work) from [<c01402d8>]
(worker_thread+0x34/0x57c)
[ 3940.036579]  r10:ef0f4180 r9:ef7b1800 r8:c0e04900 r7:ef7b1834
r6:00000008 r5:ef0f4198
[ 3940.044414]  r4:ef7b1800
[ 3940.046964] [<c01402a4>] (worker_thread) from [<c0146970>]
(kthread+0xdc/0xf8)
[ 3940.054196]  r10:00000000 r9:00000000 r8:00000000 r7:c01402a4
r6:ef0f4180 r5:ef0f7000
[ 3940.062031]  r4:00000000
[ 3940.064581] [<c0146894>] (kthread) from [<c0107e30>]
(ret_from_fork+0x14/0x24)
[ 3940.071813]  r7:00000000 r6:00000000 r5:c0146894 r4:ef0f7000
[ 3940.077578] ---[ end trace a2c0d89dc638cc35 ]---

Any ideas on how to fix it?

Thanks,

Fabio Estevam