[Bug 82763] [drm:intel_dp_start_link_train] error on connecting an external monitor on VGA

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=82763

--- Comment #1 from Daniele Pizzolli <daniele.pizzolli at create-net.org> ---
With the kernel 3.16.1 the xrandr output is correct and I am able to use the
display.

Sometimes (not reproducible) I got the following in the dmesg output:

[  205.455231] WARNING: CPU: 0 PID: 951 at drivers/gpu/drm/i915/intel_dp.c:3122
intel_dp_complete_link_train+0xe9/0x330 [i915]()
[  205.455233] Modules linked in: vboxpci(O) vboxnetadp(O) vboxnetflt(O)
vboxdrv(O) joydev arc4 nouveau dell_wmi sparse_keymap mxm_wmi iTCO_wdt
iTCO_vendor_support ppdev dell_laptop dcdbas x86_pkg_temp_thermal
intel_powerclamp intel_rapl coretemp kvm_intel kvm pcspkr ecb iwlmvm btusb
bluetooth mac80211 uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core
v4l2_common videodev media psmouse evdev serio_raw snd_hda_codec_realtek
snd_hda_codec_generic i2c_i801 iwlwifi cfg80211 ttm snd_hda_intel i915 rfkill
lpc_ich snd_hda_controller mfd_core shpchp snd_hda_codec i2c_algo_bit snd_hwdep
drm_kms_helper parport_pc parport wmi drm snd_pcm snd_timer video i2c_core
battery snd ac mei_me soundcore button mei processor loop fuse autofs4 ext4
crc16 mbcache jbd2 dm_crypt dm_mod sg sd_mod sr_mod crc_t10dif cdrom
crct10dif_generic uas usb_storage crct10dif_pclmul crct10dif_common
crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel aes_x86_64
glue_helper lrw gf128mul ablk_helper cryptd ahci sdhci_pci sdhci libahci
mmc_core libata ehci_pci ehci_hcd scsi_mod e1000e ptp pps_core xhci_hcd usbcore
usb_common thermal thermal_sys
[  205.455287] CPU: 0 PID: 951 Comm: Xorg Tainted: G           O  3.16.1mine1+
#2
[  205.455289] Hardware name: Dell Inc. Latitude E5440/08RCYC, BIOS A07
06/26/2014
[  205.455290]  0000000000000009 ffffffff814dd60d 0000000000000000
ffffffff81064c12
[  205.455293]  ffff8802204a30d8 0000000000000001 0000000000000000
ffff8802204a3118
[  205.455295]  ffff8802204a30f3 ffffffffa04c3e39 8000000201000000
0000008000770001
[  205.455297] Call Trace:
[  205.455302]  [<ffffffff814dd60d>] ? dump_stack+0x41/0x51
[  205.455305]  [<ffffffff81064c12>] ? warn_slowpath_common+0x72/0x90
[  205.455313]  [<ffffffffa04c3e39>] ? intel_dp_complete_link_train+0xe9/0x330
[i915]
[  205.455320]  [<ffffffffa04bc399>] ? intel_ddi_pre_enable+0x189/0x1e0 [i915]
[  205.455328]  [<ffffffffa04a529c>] ? haswell_crtc_enable+0x39c/0xa30 [i915]
[  205.455336]  [<ffffffffa04bcd6b>] ? intel_ddi_pll_select+0x3b/0x3c0 [i915]
[  205.455343]  [<ffffffffa04a7b27>] ? __intel_set_mode+0x817/0x1660 [i915]
[  205.455346]  [<ffffffff81297832>] ? idr_get_empty_slot+0x192/0x3b0
[  205.455350]  [<ffffffff8117e975>] ? __kmalloc+0x1d5/0x4f0
[  205.455358]  [<ffffffffa04aaefd>] ? intel_set_mode+0xd/0x30 [i915]
[  205.455365]  [<ffffffffa04abf13>] ? intel_crtc_set_config+0xa23/0xd50 [i915]
[  205.455371]  [<ffffffffa039091a>] ? drm_mode_set_config_internal+0x5a/0xd0
[drm]
[  205.455377]  [<ffffffffa039424a>] ? drm_mode_setcrtc+0x25a/0x560 [drm]
[  205.455383]  [<ffffffffa03857f3>] ? drm_ioctl+0x1c3/0x5a0 [drm]
[  205.455386]  [<ffffffff811a9640>] ? do_vfs_ioctl+0x2d0/0x4a0
[  205.455389]  [<ffffffff8108272c>] ? task_work_run+0xac/0xe0
[  205.455391]  [<ffffffff811a9889>] ? SyS_ioctl+0x79/0x90
[  205.455393]  [<ffffffff814e34ea>] ? int_signal+0x12/0x17
[  205.455396]  [<ffffffff814e322d>] ? system_call_fastpath+0x1a/0x1f


Something strange: after a reboot into 3.16 I do see the monitor in xrandr,
and no more warning in dmesg.
Maybe is because of the warm reboot?

I available for testing various configurations, if you need.

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