Hey, (CCing some people who have worked on the i915 code recently)
I've had this bug on my x240t since a while now. I mentioned it a while back on this list[1], but I didn't look very deep back then. In short: display port on docking station (HDMI2 in xrandr) doesn't always detect a monitor. Sometimes you can get it to work by suspending and resuming. Having found no clues from trying a load of different combinations of docking, undocking, changing power states, plugging and unplugging monitors etc, I finally decided to start reading code. I've made some progress, but I've hit a brick wall. I'm hoping someone can point me in the right direction. The code responsible for detecting monitors on HDMI ports is intel_hdmi_detect() in intel_hdmi.c. This calls up into drm_get_edid() in drm_edid.c. This then uses the i2c bus on the graphics card to query the port. The i2c bus code is custom for the i915 graphics card: intel_i2c.c. It seems that the difference between a successfully detected and a unsuccessfully detected HDMI2 boils down to whether the call to I915_READ() on line 210 of intel_i2c.c is successful. for (retries = 50; retries > 0; retries--) { st = I915_READ(GMBUS2 + reg_offset); if (st & (GMBUS_SATOER | GMBUS_HW_RDY)) break; DELAY(1000); } if (st & GMBUS_SATOER) { bus_err = 1; goto out; } In the case where a monitor is plugged in but X fails to detect it, the call returns GMBUS_SATOER. In cases where HDMI2 is detected properly, the function exits without error. I've gotten this far with printf debugging. The existence of my printf's seems to have changed the behaviour, so I'm wondering if there is a race some place. It used to be the case that a zzz/resume cycle would *always* cause HDMI2 to be detected OK. But since adding my printfs, HDMI2 is not reliably detected with the zzz/resume cycle any more. I've not been able to find a description of GMBUS_SATOER anywhere, but I think this should not happen, right? Hopefully I'm not chasing a red herring. [1]: http://openbsd-archive.7691.n7.nabble.com/Thinkpad-dock-only-provides-HDMI2-after-first-suspend-td273037.html dmesg (including sleep/wake cycle) follows: OpenBSD 5.9 (GENERIC.MP) #1870: Mon Feb 8 17:34:23 MST 2016 dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP real mem = 16844521472 (16064MB) avail mem = 16329822208 (15573MB) mpath0 at root scsibus0 at mpath0: 256 targets mainbus0 at root bios0 at mainbus0: SMBIOS rev. 2.7 @ 0xdae9c000 (68 entries) bios0: vendor LENOVO version "GCETA2WW (2.62 )" date 04/09/2015 bios0: LENOVO 3437CTO acpi0 at bios0: rev 2 acpi0: sleep states S0 S3 S4 S5 acpi0: tables DSDT FACP SLIC TCPA SSDT SSDT SSDT HPET APIC MCFG ECDT FPDT ASF! UEFI UEFI POAT SSDT SSDT DMAR UEFI DBG2 acpi0: wakeup devices LID_(S4) SLPB(S3) IGBE(S4) EXP3(S4) XHCI(S3) EHC1(S3) EHC2(S3) HDEF(S4) acpitimer0 at acpi0: 3579545 Hz, 24 bits acpihpet0 at acpi0: 14318179 Hz acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat cpu0 at mainbus0: apid 0 (boot processor) cpu0: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz, 2594.57 MHz cpu0: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,LONG,LAHF,PERF,ITSC,FSGSBASE,SMEP,ERMS,SENSOR,ARAT cpu0: 256KB 64b/line 8-way L2 cache cpu0: smt 0, core 0, package 0 mtrr: Pentium Pro MTRR support, 10 var ranges, 88 fixed ranges cpu0: apic clock running at 99MHz cpu0: mwait min=64, max=64, C-substates=0.2.1.1.2, IBE cpu1 at mainbus0: apid 2 (application processor) cpu1: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz, 2594.10 MHz cpu1: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,LONG,LAHF,PERF,ITSC,FSGSBASE,SMEP,ERMS,SENSOR,ARAT cpu1: 256KB 64b/line 8-way L2 cache cpu1: smt 0, core 1, package 0 ioapic0 at mainbus0: apid 2 pa 0xfec00000, version 20, 24 pins acpimcfg0 at acpi0 addr 0xf8000000, bus 0-63 acpiec0 at acpi0 acpiprt0 at acpi0: bus 0 (PCI0) acpiprt1 at acpi0: bus -1 (PEG_) acpiprt2 at acpi0: bus 2 (EXP1) acpiprt3 at acpi0: bus 3 (EXP2) acpiprt4 at acpi0: bus 4 (EXP3) acpicpu0 at acpi0: C2(350@80 mwait.1@0x20), C1(1000@1 mwait.1), PSS acpicpu1 at acpi0: C2(350@80 mwait.1@0x20), C1(1000@1 mwait.1), PSS acpipwrres0 at acpi0: PUBS, resource for XHCI, EHC1, EHC2 acpitz0 at acpi0: critical temperature is 103 degC acpibtn0 at acpi0: LID_ acpibtn1 at acpi0: SLPB acpibat0 at acpi0: BAT0 model "45N1077" serial 14278 type LION oem "SANYO" acpibat1 at acpi0: BAT1 not present acpiac0 at acpi0: AC unit online acpithinkpad0 at acpi0 acpidock0 at acpi0: GDCK docked (15) cpu0: Enhanced SpeedStep 2594 MHz: speeds: 2601, 2600, 2500, 2400, 2300, 2200, 2100, 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200 MHz pci0 at mainbus0 bus 0 pchb0 at pci0 dev 0 function 0 "Intel Core 3G Host" rev 0x09 inteldrm0 at pci0 dev 2 function 0 "Intel HD Graphics 4000" rev 0x09 drm0 at inteldrm0 inteldrm0: msi inteldrm0: 1366x768 wsdisplay0 at inteldrm0 mux 1: console (std, vt100 emulation) wsdisplay0: screen 1-5 added (std, vt100 emulation) "Intel 7 Series MEI" rev 0x04 at pci0 dev 22 function 0 not configured em0 at pci0 dev 25 function 0 "Intel 82579LM" rev 0x04: msi, address 3c:97:0e:a5:02:69 ehci0 at pci0 dev 26 function 0 "Intel 7 Series USB" rev 0x04: apic 2 int 16 usb0 at ehci0: USB revision 2.0 uhub0 at usb0 "Intel EHCI root hub" rev 2.00/1.00 addr 1 azalia0 at pci0 dev 27 function 0 "Intel 7 Series HD Audio" rev 0x04: msi azalia0: codecs: Realtek ALC269, Intel/0x2806, using Realtek ALC269 audio0 at azalia0 ppb0 at pci0 dev 28 function 0 "Intel 7 Series PCIE" rev 0xc4: msi pci1 at ppb0 bus 2 sdhc0 at pci1 dev 0 function 0 "Ricoh 5U822 SD/MMC" rev 0x07: apic 2 int 16 sdmmc0 at sdhc0 ppb1 at pci0 dev 28 function 1 "Intel 7 Series PCIE" rev 0xc4: msi pci2 at ppb1 bus 3 iwn0 at pci2 dev 0 function 0 "Intel Centrino Wireless-N 2200" rev 0xc4: msi, MIMO 2T2R, BGN, address 9c:4e:36:b8:f8:f8 ppb2 at pci0 dev 28 function 2 "Intel 7 Series PCIE" rev 0xc4: msi pci3 at ppb2 bus 4 ehci1 at pci0 dev 29 function 0 "Intel 7 Series USB" rev 0x04: apic 2 int 23 usb1 at ehci1: USB revision 2.0 uhub1 at usb1 "Intel EHCI root hub" rev 2.00/1.00 addr 1 pcib0 at pci0 dev 31 function 0 "Intel QM77 LPC" rev 0x04 ahci0 at pci0 dev 31 function 2 "Intel 7 Series AHCI" rev 0x04: msi, AHCI 1.3 ahci0: port 0: 6.0Gb/s scsibus1 at ahci0: 32 targets sd0 at scsibus1 targ 0 lun 0: <ATA, Crucial_CT240M50, MU02> SCSI3 0/direct fixed naa.500a0751093c44b5 sd0: 228936MB, 512 bytes/sector, 468862128 sectors, thin ichiic0 at pci0 dev 31 function 3 "Intel 7 Series SMBus" rev 0x04: apic 2 int 18 iic0 at ichiic0 spdmem0 at iic0 addr 0x50: 8GB DDR3 SDRAM PC3-12800 SO-DIMM spdmem1 at iic0 addr 0x51: 8GB DDR3 SDRAM PC3-12800 SO-DIMM isa0 at pcib0 isadma0 at isa0 pckbc0 at isa0 port 0x60/5 irq 1 irq 12 pckbd0 at pckbc0 (kbd slot) wskbd0 at pckbd0: console keyboard, using wsdisplay0 pms0 at pckbc0 (aux slot) wsmouse0 at pms0 mux 0 pcppi0 at isa0 port 0x61 spkr0 at pcppi0 uhub2 at uhub0 port 1 "Intel Rate Matching Hub" rev 2.00/0.00 addr 2 uhidev0 at uhub2 port 2 configuration 1 interface 0 "Logitech USB Receiver" rev 2.00/12.01 addr 3 uhidev0: iclass 3/1 ukbd0 at uhidev0: 8 variable keys, 6 key codes wskbd1 at ukbd0 mux 1 wskbd1: connecting to wsdisplay0 uhidev1 at uhub2 port 2 configuration 1 interface 1 "Logitech USB Receiver" rev 2.00/12.01 addr 3 uhidev1: iclass 3/1, 8 report ids ums0 at uhidev1 reportid 2: 16 buttons, Z and W dir wsmouse1 at ums0 mux 0 uhid0 at uhidev1 reportid 3: input=4, output=0, feature=0 uhid1 at uhidev1 reportid 4: input=1, output=0, feature=0 uhid2 at uhidev1 reportid 8: input=1, output=0, feature=0 uhidev2 at uhub2 port 2 configuration 1 interface 2 "Logitech USB Receiver" rev 2.00/12.01 addr 3 uhidev2: iclass 3/0, 33 report ids uhid3 at uhidev2 reportid 16: input=6, output=6, feature=0 uhid4 at uhidev2 reportid 17: input=19, output=19, feature=0 uhid5 at uhidev2 reportid 32: input=14, output=14, feature=0 uhid6 at uhidev2 reportid 33: input=31, output=31, feature=0 ugen0 at uhub2 port 4 "Broadcom Corp BCM20702A0" rev 2.00/1.12 addr 4 uvideo0 at uhub2 port 6 configuration 1 interface 0 "Chicony Electronics Co., Ltd. Integrated Camera" rev 2.00/5.20 addr 5 video0 at uvideo0 uhub3 at uhub1 port 1 "Intel Rate Matching Hub" rev 2.00/0.00 addr 2 uhub4 at uhub3 port 3 "Standard Microsystems product 0x2514" rev 2.00/0.00 addr 3 uhidev3 at uhub3 port 5 configuration 1 interface 0 "Tablet ISD-V4" rev 1.10/6.11 addr 4 uhidev3: iclass 3/1, 2 report ids ums1 at uhidev3 reportid 1: 2 buttons wsmouse2 at ums1 mux 0 ums2 at uhidev3 reportid 2: 3 buttons, tip, barrel, eraser wsmouse3 at ums2 mux 0 vscsi0 at root scsibus2 at vscsi0: 256 targets softraid0 at root scsibus3 at softraid0: 256 targets root on sd0a (a81068940d057f4c.a) swap on sd0b dump on sd0b uhidev4 at uhub4 port 4 configuration 1 interface 0 "SEJIN SEJIN USB joint Keyboard" rev 1.10/1.30 addr 5 uhidev4: iclass 3/1 ukbd1 at uhidev4: 8 variable keys, 6 key codes wskbd2 at ukbd1 mux 1 wskbd2: connecting to wsdisplay0 wskbd1: disconnecting from wsdisplay0 wskbd1 detached ukbd0 detached uhidev0 detached wsmouse1 detached ums0 detached uhid0 detached uhid1 detached uhid2 detached uhidev1 detached uhid3 detached uhid4 detached uhid5 detached uhid6 detached uhidev2 detached ugen0 detached video0 detached uvideo0 detached uhub2 detached uhub0 detached wskbd2: disconnecting from wsdisplay0 wskbd2 detached ukbd1 detached uhidev4 detached uhub4 detached wsmouse2 detached ums1 detached wsmouse3 detached ums2 detached uhidev3 detached uhub3 detached uhub1 detached uhub0 at usb0 "Intel EHCI root hub" rev 2.00/1.00 addr 1 uhub1 at usb1 "Intel EHCI root hub" rev 2.00/1.00 addr 1 uhub2 at uhub0 port 1 "Intel Rate Matching Hub" rev 2.00/0.00 addr 2 uhidev0 at uhub2 port 2 configuration 1 interface 0 "Logitech USB Receiver" rev 2.00/12.01 addr 3 uhidev0: iclass 3/1 ukbd0 at uhidev0: 8 variable keys, 6 key codes wskbd1 at ukbd0 mux 1 wskbd1: connecting to wsdisplay0 uhidev1 at uhub2 port 2 configuration 1 interface 1 "Logitech USB Receiver" rev 2.00/12.01 addr 3 uhidev1: iclass 3/1, 8 report ids ums0 at uhidev1 reportid 2: 16 buttons, Z and W dir wsmouse1 at ums0 mux 0 uhid0 at uhidev1 reportid 3: input=4, output=0, feature=0 uhid1 at uhidev1 reportid 4: input=1, output=0, feature=0 uhid2 at uhidev1 reportid 8: input=1, output=0, feature=0 uhidev2 at uhub2 port 2 configuration 1 interface 2 "Logitech USB Receiver" rev 2.00/12.01 addr 3 uhidev2: iclass 3/0, 33 report ids uhid3 at uhidev2 reportid 16: input=6, output=6, feature=0 uhid4 at uhidev2 reportid 17: input=19, output=19, feature=0 uhid5 at uhidev2 reportid 32: input=14, output=14, feature=0 uhid6 at uhidev2 reportid 33: input=31, output=31, feature=0 ugen0 at uhub2 port 4 "Broadcom Corp BCM20702A0" rev 2.00/1.12 addr 4 uvideo0 at uhub2 port 6 configuration 1 interface 0 "Chicony Electronics Co., Ltd. Integrated Camera" rev 2.00/5.20 addr 5 video0 at uvideo0 uhub3 at uhub1 port 1 "Intel Rate Matching Hub" rev 2.00/0.00 addr 2 uhub4 at uhub3 port 3 "Standard Microsystems product 0x2514" rev 2.00/0.00 addr 3 uhidev3 at uhub3 port 5 configuration 1 interface 0 "Tablet ISD-V4" rev 1.10/6.11 addr 4 uhidev3: iclass 3/1, 2 report ids ums1 at uhidev3 reportid 1: 2 buttons wsmouse2 at ums1 mux 0 ums2 at uhidev3 reportid 2: 3 buttons, tip, barrel, eraser wsmouse3 at ums2 mux 0 uhidev4 at uhub4 port 4 configuration 1 interface 0 "SEJIN SEJIN USB joint Keyboard" rev 1.10/1.30 addr 5 uhidev4: iclass 3/1 ukbd1 at uhidev4: 8 variable keys, 6 key codes wskbd2 at ukbd1 mux 1 wskbd2: connecting to wsdisplay0 -- Best Regards Edd Barrett http://www.theunixzoo.co.uk