FYI, we noticed the below changes on

git://anongit.freedesktop.org/drm-intel topic/core-stuff
commit 89d4375a050de1a2625a1ad3d0df9a57972b8c1a ("drm/probe-helper: don't lose hotplug event")


+-------------------------------------------------------+------------+------------+
|                                                       | 42c5814c9c | 89d4375a05 |
+-------------------------------------------------------+------------+------------+
| boot_successes                                        | 20         | 10         |
| early-boot-hang                                       | 1          |            |
| boot_failures                                         | 0          | 10         |
| WARNING:at_kernel/workqueue.c:#__queue_delayed_work() | 0          | 10         |
| WARNING:at_kernel/workqueue.c:#__queue_work()         | 0          | 10         |
| backtrace:drm_fb_helper_initial_config                | 0          | 10         |
| backtrace:mgag200_fbdev_init                          | 0          | 10         |
| backtrace:mgag200_modeset_init                        | 0          | 10         |
| backtrace:__pci_register_driver                       | 0          | 6          |
| backtrace:drm_pci_init                                | 0          | 6          |
| backtrace:mgag200_init                                | 0          | 6          |
| backtrace:load_module                                 | 0          | 6          |
| backtrace:SyS_finit_module                            | 0          | 6          |
| backtrace:work_for_cpu_fn                             | 0          | 4          |
+-------------------------------------------------------+------------+------------+


[   27.963836] ata2: SATA link down (SStatus 0 SControl 300)
[   27.965776] ata6: SATA link down (SStatus 0 SControl 300)
[   27.981757] ------------[ cut here ]------------
[   27.981762] WARNING: CPU: 3 PID: 528 at kernel/workqueue.c:1427 __queue_delayed_work+0x1a9/0x1c0()
[   27.981773] Modules linked in: mgag200(+) isci syscopyarea sysfillrect kvm sysimgblt ttm libsas drm_kms_helper crct10dif_pclmul scsi_transport_sas crc32_pclmul crc32c_intel snd_timer ghash_clmulni_intel drm snd soundcore aesni_intel ahci lrw libahci gf128mul sb_edac glue_helper ablk_helper cryptd pcspkr libata edac_core i2c_i801 ipmi_si microcode shpchp wmi acpi_cpufreq(-) pcc_cpufreq(-) ipmi_msghandler
[   27.981775] CPU: 3 PID: 528 Comm: systemd-udevd Not tainted 3.19.0-rc5-wl-gd6a2e8c #1
[   27.981776] Hardware name: Intel Corporation S2600WP/S2600WP, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
[   27.981778]  ffffffff81b77eb8 ffff880808d0b7c8 ffffffff818a5630 00000000419c419c
[   27.981779]  0000000000000000 ffff880808d0b808 ffffffff810726ba 0000000000000286
[   27.981780]  0000000000002000 ffff88081e80ce00 ffff88081a7c2bf8 ffff88081a7c2800
[   27.981781] Call Trace:
[   27.981785]  [<ffffffff818a5630>] dump_stack+0x4c/0x65
[   27.981787]  [<ffffffff810726ba>] warn_slowpath_common+0x8a/0xc0
[   27.981788]  [<ffffffff810727aa>] warn_slowpath_null+0x1a/0x20
[   27.981789]  [<ffffffff81089f39>] __queue_delayed_work+0x1a9/0x1c0
[   27.981790]  [<ffffffff8108a15b>] queue_delayed_work_on+0x2b/0x50
[   27.981794]  [<ffffffffa0295b45>] drm_helper_probe_single_connector_modes_merge_bits+0x2f5/0x4e0 [drm_kms_helper]
[   27.981796]  [<ffffffff810dbce0>] ? internal_add_timer+0xb0/0xb0
[   27.981799]  [<ffffffffa0295d43>] drm_helper_probe_single_connector_modes+0x13/0x20 [drm_kms_helper]
[   27.981803]  [<ffffffffa029f780>] drm_fb_helper_probe_connector_modes+0x50/0x70 [drm_kms_helper]
[   27.981806]  [<ffffffffa02a0b9d>] drm_fb_helper_initial_config+0x4d/0x3a0 [drm_kms_helper]
[   27.981817]  [<ffffffffa02f4932>] ? drm_modeset_unlock_all+0x42/0x70 [drm]
[   27.981820]  [<ffffffffa02116c3>] mgag200_fbdev_init+0x103/0x130 [mgag200]
[   27.981823]  [<ffffffffa021011c>] mgag200_modeset_init+0x17c/0x1e0 [mgag200]
[   27.981825]  [<ffffffffa020c65d>] mgag200_driver_load+0x3ad/0x520 [mgag200]
[   27.981831]  [<ffffffffa02de7d5>] drm_dev_register+0xb5/0x110 [drm]
[   27.981837]  [<ffffffffa02e183d>] drm_get_pci_dev+0x8d/0x200 [drm]
[   27.981840]  [<ffffffffa0210e8f>] mga_pci_probe+0x9f/0xc0 [mgag200]
[   27.981841]  [<ffffffff81445755>] local_pci_probe+0x45/0xa0
[   27.981843]  [<ffffffff81446ac5>] ? pci_match_device+0xe5/0x110
[   27.981844]  [<ffffffff81446c01>] pci_device_probe+0xd1/0x120
[   27.981847]  [<ffffffff8154b780>] driver_probe_device+0x90/0x3e0
[   27.981848]  [<ffffffff8154bbab>] __driver_attach+0x9b/0xa0
[   27.981850]  [<ffffffff8154bb10>] ? __device_attach+0x40/0x40
[   27.981851]  [<ffffffff8154955b>] bus_for_each_dev+0x6b/0xb0
[   27.981852]  [<ffffffff8154b1fe>] driver_attach+0x1e/0x20
[   27.981854]  [<ffffffff8154adc0>] bus_add_driver+0x180/0x250
[   27.981855]  [<ffffffff8154c3b4>] driver_register+0x64/0xf0
[   27.981856]  [<ffffffff81444fac>] __pci_register_driver+0x4c/0x50
[   27.981861]  [<ffffffffa02e1aaa>] drm_pci_init+0xfa/0x130 [drm]
[   27.981863]  [<ffffffffa0061000>] ? 0xffffffffa0061000
[   27.981865]  [<ffffffffa006103c>] mgag200_init+0x3c/0x1000 [mgag200]
[   27.981868]  [<ffffffff81002130>] do_one_initcall+0xc0/0x1f0
[   27.981870]  [<ffffffff811c7dec>] ? kmem_cache_alloc_trace+0x1dc/0x250
[   27.981872]  [<ffffffff810fa499>] ? load_module+0x1449/0x1b70
[   27.981873]  [<ffffffff810fa4d2>] load_module+0x1482/0x1b70
[   27.981874]  [<ffffffff810f5ef0>] ? store_uevent+0x40/0x40
[   27.981876]  [<ffffffff810fad66>] SyS_finit_module+0x86/0xb0
[   27.981879]  [<ffffffff818add69>] system_call_fastpath+0x12/0x17
[   27.981880] ---[ end trace cc8beb3d70a21b78 ]---
[   27.981880] ------------[ cut here ]------------


Thanks,
Huang, Ying