我的 dmesg 中有一个令人担忧的条目。
我的内核：
$ uname -a
Linux metric 4.8.0-41-generic #44-Ubuntu SMP Fri Mar 3 15:27:17 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
我的显卡：
$ sudo lspci | grep VGA
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde XT [Radeon HD 7770/8760 / R7 250X]
每次启动时，我都会得到这个：
[ 7.228303] [drm] initializing kernel modesetting (VERDE 0x1002:0x683D 0x1043:0x045D 0x00).
[ 7.228327] [drm] register mmio base: 0xFCDC0000
[ 7.228332] [drm] register mmio size: 262144
[ 7.228433] ATOM BIOS: 683D.15.21.0.0.AS01
[ 7.228575] radeon 0000:01:00.0: VRAM: 1024M 0x0000000000000000 - 0x000000003FFFFFFF (1024M used)
[ 7.228582] radeon 0000:01:00.0: GTT: 2048M 0x0000000040000000 - 0x00000000BFFFFFFF
[ 7.228588] [drm] Detected VRAM RAM=1024M, BAR=256M
[ 7.228591] [drm] RAM width 128bits DDR
[ 7.228694] [TTM] Zone kernel: Available graphics memory: 15828162 kiB
[ 7.228703] [TTM] Zone dma32: Available graphics memory: 2097152 kiB
[ 7.228708] [TTM] Initializing pool allocator
[ 7.228724] [TTM] Initializing DMA pool allocator
[ 7.228763] [drm] radeon: 1024M of VRAM memory ready
[ 7.228769] [drm] radeon: 2048M of GTT memory ready.
[ 7.228791] [drm] Loading verde Microcode
[ 7.228968] [drm] Internal thermal controller with fan control
[ 7.229055] [drm] probing gen 2 caps for device 8086:4021 = 4394d02/0
[ 7.235853] [drm] radeon: dpm initialized
[ 7.238026] [drm] Found VCE firmware/feedback version 50.0.1 / 17!
[ 7.238038] [drm] GART: num cpu pages 524288, num gpu pages 524288
[ 7.240889] [drm] probing gen 2 caps for device 8086:4021 = 4394d02/0
[ 7.240901] [drm] PCIE gen 2 link speeds already enabled
[ 7.278757] [drm] PCIE GART of 2048M enabled (table at 0x00000000001D6000).
[ 7.278892] radeon 0000:01:00.0: WB enabled
[ 7.278898] radeon 0000:01:00.0: fence driver on ring 0 use gpu addr 0x0000000040000c00 and cpu addr 0xffff99b5439a9c00
[ 7.278904] radeon 0000:01:00.0: fence driver on ring 1 use gpu addr 0x0000000040000c04 and cpu addr 0xffff99b5439a9c04
[ 7.278911] radeon 0000:01:00.0: fence driver on ring 2 use gpu addr 0x0000000040000c08 and cpu addr 0xffff99b5439a9c08
[ 7.278917] radeon 0000:01:00.0: fence driver on ring 3 use gpu addr 0x0000000040000c0c and cpu addr 0xffff99b5439a9c0c
[ 7.278923] radeon 0000:01:00.0: fence driver on ring 4 use gpu addr 0x0000000040000c10 and cpu addr 0xffff99b5439a9c10
[ 7.279293] radeon 0000:01:00.0: fence driver on ring 5 use gpu addr 0x0000000000075a18 and cpu addr 0xffffabef44035a18
[ 7.299297] radeon 0000:01:00.0: fence driver on ring 6 use gpu addr 0x0000000040000c18 and cpu addr 0xffff99b5439a9c18
[ 7.299304] radeon 0000:01:00.0: fence driver on ring 7 use gpu addr 0x0000000040000c1c and cpu addr 0xffff99b5439a9c1c
[ 7.299310] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 7.299314] [drm] Driver supports precise vblank timestamp query.
[ 7.299318] radeon 0000:01:00.0: radeon: MSI limited to 32-bit
[ 7.299371] radeon 0000:01:00.0: radeon: using MSI.
[ 7.299405] [drm] radeon: irq initialized.
[ 7.580009] ioc0: LSISAS1068E B3: Capabilities={Initiator}
[ 7.775188] [drm] ring test on 0 succeeded in 1 usecs
[ 7.775201] [drm] ring test on 1 succeeded in 1 usecs
[ 7.775207] [drm] ring test on 2 succeeded in 1 usecs
[ 7.775222] [drm] ring test on 3 succeeded in 9 usecs
[ 7.775230] [drm] ring test on 4 succeeded in 3 usecs
[ 7.950916] [drm] ring test on 5 succeeded in 2 usecs
[ 7.950925] [drm] UVD initialized successfully.
[ 8.060126] [drm] ring test on 6 succeeded in 21 usecs
[ 8.060140] [drm] ring test on 7 succeeded in 3 usecs
[ 8.060143] [drm] VCE initialized successfully.
[ 8.060633] [drm] ib test on ring 0 succeeded in 0 usecs
[ 8.060661] [drm] ib test on ring 1 succeeded in 0 usecs
[ 8.060688] [drm] ib test on ring 2 succeeded in 0 usecs
[ 8.060765] [drm] ib test on ring 3 succeeded in 0 usecs
[ 8.060813] [drm] ib test on ring 4 succeeded in 0 usecs
[ 8.672035] floppy0: no floppy controllers found
[ 8.736038] [drm] ib test on ring 5 succeeded
[ 9.248037] [drm] ib test on ring 6 succeeded
[ 9.760024] [drm] ib test on ring 7 succeeded
[ 9.761065] [drm] Radeon Display Connectors
[ 9.761078] [drm] Connector 0:
[ 9.761081] [drm] DP-1
[ 9.761084] [drm] HPD4
[ 9.761088] [drm] DDC: 0x6540 0x6540 0x6544 0x6544 0x6548 0x6548 0x654c 0x654c
[ 9.761092] [drm] Encoders:
[ 9.761095] [drm] DFP1: INTERNAL_UNIPHY2
[ 9.761099] [drm] Connector 1:
[ 9.761101] [drm] HDMI-A-1
[ 9.761104] [drm] HPD3
[ 9.761107] [drm] DDC: 0x6530 0x6530 0x6534 0x6534 0x6538 0x6538 0x653c 0x653c
[ 9.761112] [drm] Encoders:
[ 9.761114] [drm] DFP2: INTERNAL_UNIPHY2
[ 9.761117] [drm] Connector 2:
[ 9.761120] [drm] DVI-I-1
[ 9.761122] [drm] HPD1
[ 9.761126] [drm] DDC: 0x6560 0x6560 0x6564 0x6564 0x6568 0x6568 0x656c 0x656c
[ 9.761130] [drm] Encoders:
[ 9.761133] [drm] DFP3: INTERNAL_UNIPHY
[ 9.761136] [drm] CRT1: INTERNAL_KLDSCP_DAC1
[ 9.823031] [drm] fb mappable at 0xD05D9000
[ 9.823035] [drm] vram apper at 0xD0000000
[ 9.823038] [drm] size 8294400
[ 9.823041] [drm] fb depth is 24
[ 9.823043] [drm] pitch is 6912
[ 9.823105] fbcon: radeondrmfb (fb0) is primary device
[ 9.861409] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery tried 5 times
[ 9.861450] [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
[ 9.881669] Console: switching to colour frame buffer device 200x65
[ 9.885004] radeon 0000:01:00.0: fb0: radeondrmfb frame buffer device
[ 9.900036] [drm] Initialized radeon 2.46.0 20080528 for 0000:01:00.0 on minor 0
[ 10.805071] ------------[ cut here ]------------
[ 10.805119] WARNING: CPU: 4 PID: 75 at /build/linux-xXpTKI/linux-4.8.0/include/drm/drm_crtc.h:3131 drm_helper_choose_encoder_dpms+0x8a/0x90 [drm_kms_helper]
[ 10.805186] Modules linked in: amdkfd amd_iommu_v2 radeon i2c_algo_bit ttm drm_kms_helper tg3 syscopyarea sysfillrect ptp sysimgblt mptsas(+) hid_generic fb_sys_fops mptscsih usbhid mptbase hid pata_acpi drm pps_core ahci scsi_transport_sas libahci
[ 10.805363] CPU: 4 PID: 75 Comm: kworker/4:1 Not tainted 4.8.0-41-generic #44-Ubuntu
[ 10.805393] Hardware name: Dell Inc. Precision WorkStation T7400 /0RW199, BIOS A11 04/30/2012
[ 10.805474] Workqueue: events radeon_dp_work_func [radeon]
[ 10.805500] 0000000000000286 000000000e7db13a ffff99b54c9fbd18 ffffffff82830e92
[ 10.805542] 0000000000000000 0000000000000000 ffff99b54c9fbd58 ffffffff8248319b
[ 10.805583] 00000c3b43a39488 ffff99b54cdcb800 ffff99b543c91600 ffff99b543a3b000
[ 10.805625] Call Trace:
[ 10.805641] [<ffffffff82830e92>] dump_stack+0x63/0x81
[ 10.805664] [<ffffffff8248319b>] __warn+0xcb/0xf0
[ 10.805685] [<ffffffff824832cd>] warn_slowpath_null+0x1d/0x20
[ 10.805712] [<ffffffffc047150a>] drm_helper_choose_encoder_dpms+0x8a/0x90 [drm_kms_helper]
[ 10.805744] [<ffffffffc04715fb>] drm_helper_connector_dpms+0x4b/0x100 [drm_kms_helper]
[ 10.805785] [<ffffffffc04d3917>] radeon_connector_hotplug+0xf7/0x100 [radeon]
[ 10.805828] [<ffffffffc04e174f>] radeon_dp_work_func+0x3f/0x60 [radeon]
[ 10.805856] [<ffffffff8249d96c>] process_one_work+0x1fc/0x4b0
[ 10.805880] [<ffffffff8249dc6b>] worker_thread+0x4b/0x500
[ 10.805902] [<ffffffff8249dc20>] ? process_one_work+0x4b0/0x4b0
[ 10.805927] [<ffffffff8249dc20>] ? process_one_work+0x4b0/0x4b0
[ 10.805952] [<ffffffff824a40d8>] kthread+0xd8/0xf0
[ 10.805972] [<ffffffff82ca071f>] ret_from_fork+0x1f/0x40
[ 10.805992] [<ffffffff824a4000>] ? kthread_create_on_node+0x1e0/0x1e0
[ 10.806017] ---[ end trace 54c886ab4efdb67a ]---
[ 10.806037] ------------[ cut here ]------------
[ 10.806061] WARNING: CPU: 4 PID: 75 at /build/linux-xXpTKI/linux-4.8.0/include/drm/drm_crtc.h:3131 drm_helper_choose_crtc_dpms+0x93/0xa0 [drm_kms_helper]
[ 10.806104] Modules linked in: amdkfd amd_iommu_v2 radeon i2c_algo_bit ttm drm_kms_helper tg3 syscopyarea sysfillrect ptp sysimgblt mptsas(+) hid_generic fb_sys_fops mptscsih usbhid mptbase hid pata_acpi drm pps_core ahci scsi_transport_sas libahci
[ 10.806268] CPU: 4 PID: 75 Comm: kworker/4:1 Tainted: G W 4.8.0-41-generic #44-Ubuntu
[ 10.806302] Hardware name: Dell Inc. Precision WorkStation T7400 /0RW199, BIOS A11 04/30/2012
[ 10.806350] Workqueue: events radeon_dp_work_func [radeon]
[ 10.806376] 0000000000000286 000000000e7db13a ffff99b54c9fbd18 ffffffff82830e92
[ 10.806417] 0000000000000000 0000000000000000 ffff99b54c9fbd58 ffffffff8248319b
[ 10.807990] 00000c3b43a39488 ffff99b54cdcb800 ffff99b543a3b000 ffff99b543a3b000
[ 10.809053] Call Trace:
[ 10.809053] [<ffffffff82830e92>] dump_stack+0x63/0x81
[ 10.809053] [<ffffffff8248319b>] __warn+0xcb/0xf0
[ 10.809053] [<ffffffff824832cd>] warn_slowpath_null+0x1d/0x20
[ 10.809053] [<ffffffffc04715a3>] drm_helper_choose_crtc_dpms+0x93/0xa0 [drm_kms_helper]
[ 10.809053] [<ffffffffc0471627>] drm_helper_connector_dpms+0x77/0x100 [drm_kms_helper]
[ 10.809053] [<ffffffffc04ba010>] ? atombios_blank_crtc+0x150/0x150 [radeon]
[ 10.809053] [<ffffffffc04d3917>] radeon_connector_hotplug+0xf7/0x100 [radeon]
[ 10.809053] [<ffffffffc04e174f>] radeon_dp_work_func+0x3f/0x60 [radeon]
[ 10.809053] [<ffffffff8249d96c>] process_one_work+0x1fc/0x4b0
[ 10.809053] [<ffffffff8249dc6b>] worker_thread+0x4b/0x500
[ 10.809053] [<ffffffff8249dc20>] ? process_one_work+0x4b0/0x4b0
[ 10.809053] [<ffffffff8249dc20>] ? process_one_work+0x4b0/0x4b0
[ 10.809053] [<ffffffff824a40d8>] kthread+0xd8/0xf0
[ 10.809053] [<ffffffff82ca071f>] ret_from_fork+0x1f/0x40
[ 10.809053] [<ffffffff824a4000>] ? kthread_create_on_node+0x1e0/0x1e0
[ 10.834872] ---[ end trace 54c886ab4efdb67b ]---
然后它挂起约 25 秒，然后继续。显卡似乎能够恢复，因为在运行时我没有看到任何图形问题。
这是什么原因造成的？有什么方法可以修复它吗？