Linux Kernel 4.4.0-66 Possible DRM connector_status Bug For LG Displays

Tom Reddish tom.reddish at mediavuesystems.com
Wed May 31 16:43:52 UTC 2017


What do you mean by bisect?

My gut is telling me it's something that changed in the kernel. Maybe the kernel is correctly parsing the information it is being given from the display now and in the older kernel it was handling that information differently? With the exact same display and no settings changed on it if I use the older kernel it shows up as connected

Tom Reddish 
Software Engineer
MediaVue Systems
Skype: t.reddish
Tel: +1 781.926.0676
w <applewebdata://FF6402AA-2601-418F-BA35-F485629555D0/www.mediavuesystems.com>ww.mediavuesystems.com <applewebdata://FF6402AA-2601-418F-BA35-F485629555D0/www.mediavuesystems.com>
> On May 31, 2017, at 12:24 PM, Deucher, Alexander <Alexander.Deucher at amd.com> wrote:
> 
> Can you bisect?  Sounds like the monitor does not keep the EDID powered up when the display is off as is required by the vesa spec.
>  
> Alex
>  
> From: Tom Reddish [mailto:tom.reddish at mediavuesystems.com] 
> Sent: Wednesday, May 31, 2017 12:20 PM
> To: Deucher, Alexander; Koenig, Christian
> Cc: amd-gfx at lists.freedesktop.org; Brian Kane
> Subject: Linux Kernel 4.4.0-66 Possible DRM connector_status Bug For LG Displays
>  
>  
> LG Displays are being reported as "disconnected" when they are powered off (currently connected through DVI to mini-displayport adapter)
>  
> Only seeing this with LG displays (have tested NEC and Samsung *limited model types for each manufacturer*). With the LG display connected to the graphics card and powered off the system is reporting the DisplayPort as disconnected. In any kernel <= 4.4.0-31 the system would report the DisplayPort as connected even if the LG display was off. 
>  
> Kernel tested on
> Linux version 4.4.0-66-generic (buildd at lgw01-28) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4) ) #87-Ubuntu
>  
> Most recent kernel without the bug: 
> Linux version 4.4.0-31-generic (buildd at lgw01-16) (gcc version 5.3.1 20160413 (Ubuntu 5.3.1-14ubuntu2.1) ) #50-Ubuntu
>  
> "cat /sys/class/drm/card1-DP-1/status" will show the status as disconnected if the LG display is powered off
>  
> Environment
>           Ubuntu 16.04
>           Graphics Card: Cape Verde PRO [Radeon HD 7750/8740 / R7 250E]
>           Radeon Graphics Drivers
>           Kernel: 4.4.0-66
>  
>  
> Processor
> processor       : 0-3
> vendor_id      : AuthenticAMD
> cpu family     : 21
> model                        : 48
> model name   : AMD A8-7600 Radeon R7, 10 Compute Cores 4C+6G
> stepping         : 1
> microcode      : 0x6003106
> cpu MHz                   : 1400.000
> cache size      : 2048 KB
> physical id     : 0
> siblings          : 4
> core id                       : 0
> cpu cores       : 2
> apicid             : 16
> initial apicid   : 0
> fpu                 : yes
> fpu_exception           : yes
> cpuid level     : 13
> wp                 : yes
> flags               : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc extd_apicid aperfmperf eagerfpu pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 popcnt aes xsave avx f16c lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 tce nodeid_msr tbm topoext perfctr_core perfctr_nb bpext cpb hw_pstate vmmcall fsgsbase bmi1 xsaveopt arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold
> bugs               : fxsave_leak sysret_ss_attrs
> bogomips       : 6188.48
> TLB size        : 1536 4K pages
> clflush size     : 64
> cache_alignment        : 64
> address sizes  : 48 bits physical, 48 bits virtual
> power management: ts ttp tm 100mhzsteps hwpstate cpb eff_freq_ro [13]
>  
>  
> Loaded driver and hardware information
> cat /proc/ioports:
> 0000-03af : PCI Bus 0000:00
>   0000-001f : dma1
>   0020-0021 : pic1
>   0040-0043 : timer0
>   0050-0053 : timer1
>   0060-0060 : keyboard
>   0061-0061 : PNP0800:00
>   0064-0064 : keyboard
>   0070-0071 : rtc0
>   0080-008f : dma page reg
>   00a0-00a1 : pic2
>   00c0-00df : dma2
>   00f0-00ff : PNP0C04:00
>     00f0-00ff : fpu
> 03b0-03df : PCI Bus 0000:00
>   03c0-03df : vesafb
> 03e0-0cf7 : PCI Bus 0000:00
>   03f8-03ff : serial
>   040b-040b : pnp 00:08
>   04d0-04d1 : pnp 00:07
>     04d0-04d1 : pnp 00:08
>   04d6-04d6 : pnp 00:08
>   0800-0803 : ACPI PM1a_EVT_BLK
>   0804-0805 : ACPI PM1a_CNT_BLK
>   0808-080b : ACPI PM_TMR
>   0810-0815 : ACPI CPU throttle
>   0820-0827 : ACPI GPE0_BLK
>   0900-090f : pnp 00:08
>   0910-091f : pnp 00:08
>   0a00-0a0f : pnp 00:03
>     0a00-0a07 : f71882fg
>   0a10-0a1f : pnp 00:03
>   0b00-0b07 : piix4_smbus
>   0b20-0b3f : pnp 00:08
>     0b20-0b27 : piix4_smbus
>   0c00-0c01 : pnp 00:08
>   0c14-0c14 : pnp 00:08
>   0c50-0c51 : pnp 00:08
>   0c52-0c52 : pnp 00:08
>   0c6c-0c6c : pnp 00:08
>   0c6f-0c6f : pnp 00:08
>   0cd0-0cd1 : pnp 00:08
>   0cd2-0cd3 : pnp 00:08
>   0cd4-0cd5 : pnp 00:08
>   0cd6-0cd7 : pnp 00:08
>   0cd8-0cdf : pnp 00:08
> 0cf8-0cff : PCI conf1
> 0d00-ffff : PCI Bus 0000:00
>   d000-dfff : PCI Bus 0000:02
>     d000-d0ff : 0000:02:00.0
>       d000-d0ff : r8169
>   e000-efff : PCI Bus 0000:01
>     e000-e0ff : 0000:01:00.0
>   f000-f0ff : 0000:00:01.0
>   f100-f10f : 0000:00:11.0
>     f100-f10f : ahci
>   f110-f113 : 0000:00:11.0
>     f110-f113 : ahci
>   f120-f127 : 0000:00:11.0
>     f120-f127 : ahci
>   f130-f133 : 0000:00:11.0
>     f130-f133 : ahci
>   f140-f147 : 0000:00:11.0
>     f140-f147 : ahci
>   fe00-fefe : pnp 00:08
>  
> PCI Information
> 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde PRO [Radeon HD 7750/8740 / R7 250E] (prog-if 00 [VGA controller])
>           Subsystem: Hightech Information System Ltd. Cape Verde PRO [Radeon HD 7750/8740 / R7 250E]
>           Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
>           Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
>           Latency: 0, Cache Line Size: 64 bytes
>           Interrupt: pin A routed to IRQ 48
>           Region 0: Memory at c0000000 (64-bit, prefetchable) [size=256M]
>           Region 2: Memory at fea00000 (64-bit, non-prefetchable) [size=256K]
>           Region 4: I/O ports at e000 [size=256]
>           Expansion ROM at fea40000 [disabled] [size=128K]
>           Capabilities: [48] Vendor Specific Information: Len=08 <?>
>           Capabilities: [50] Power Management version 3
>                       Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1+,D2+,D3hot+,D3cold-)
>                       Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
>           Capabilities: [58] Express (v2) Legacy Endpoint, MSI 00
>                       DevCap:          MaxPayload 256 bytes, PhantFunc 0, Latency L0s <4us, L1 unlimited
>                                   ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
>                       DevCtl:           Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
>                                   RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
>                                   MaxPayload 256 bytes, MaxReadReq 512 bytes
>                       DevSta:           CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr- TransPend-
>                       LnkCap:          Port #0, Speed 8GT/s, Width x16, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
>                                   ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp+
>                       LnkCtl:            ASPM Disabled; RCB 64 bytes Disabled- CommClk+
>                                   ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
>                       LnkSta:           Speed 8GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
>                       DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, OBFF Not Supported
>                       DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
>                       LnkCtl2: Target Link Speed: 8GT/s, EnterCompliance- SpeedDis-
>                                    Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
>                                    Compliance De-emphasis: -6dB
>                       LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete+, EqualizationPhase1+
>                                    EqualizationPhase2+, EqualizationPhase3+, LinkEqualizationRequest-
>           Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
>                       Address: 00000000fee00000  Data: 0000
>           Capabilities: [100 v1] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
>           Capabilities: [150 v2] Advanced Error Reporting
>                       UESta:            DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
>                       UEMsk:           DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
>                       UESvrt:           DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
>                       CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
>                       CEMsk:           RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
>                       AERCap:        First Error Pointer: 00, GenCap+ CGenEn- ChkCap+ ChkEn-
>           Capabilities: [200 v1] #15
>           Capabilities: [270 v1] #19
>           Kernel driver in use: radeon
>           Kernel modules: radeon
>  
>  
>  
>  
> Tom Reddish 
> Software Engineer
> MediaVue Systems
> Skype: t.reddish
> Tel: +1 781.926.0676
> w <x-msg://8/www.mediavuesystems.com>ww.mediavuesystems.com <x-msg://8/www.mediavuesystems.com>
>  

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