X freezes for a second or every now and then when lid closed

[Joel Fernandes]

Hi!
My Linux laptop running kernel v4.17 freezes intermittently when the laptop
lid is closed but external monitors are connected to 2 HDMI ports. I provided
details on the issue, any idea what could be causing it?

I ruled out many different subsystems by trial and error, finally I enabled
ftrace events on power subsystem and see that the freeze is precisely at the
same time as drm_mode_getconnector is called on these events and its the Xorg
process. I think since Xorg is busy on this drm_mode_getconnector ioctl, its
not able to perform its duties.

I get a stacktrace like so:
	    Xorg-1285  [001] ....   801.156606: pm_qos_update_request:
	         pm_qos_class=CPU_DMA_LATENCY value=-1
	    Xorg-1285  [001] ....   801.156607: pm_qos_update_target:
	         action=UPDATE_REQ prev_value=0 curr_value=2000000000
	    Xorg-1285  [001] ....   801.156609: <stack trace>
 => pm_qos_update_target
 => intel_dp_aux_xfer
 => intel_dp_aux_transfer
 => drm_dp_dpcd_access
 => drm_dp_dpcd_read
 => intel_dp_read_dpcd
 => intel_dp_detect
 => drm_helper_probe_single_connector_modes
 => drm_mode_getconnector
 => drm_ioctl_kernel
 => drm_ioctl
 => do_vfs_ioctl
 => ksys_ioctl
 => __x64_sys_ioctl
 => do_syscall_64
 => entry_SYSCALL_64_after_hwframe

The X version I'm running is X.Org X Server 1.19.6

I also see these in /var/log/Xorg.0.log every 30 seconds and it seems
correlated to the time of freezing:
[  1141.925] (--) modeset(0): HDMI max TMDS frequency 170000KHz
[  1142.223] (II) modeset(0): EDID vendor "HWP", prod id 13093
[  1142.223] (II) modeset(0): Using hsync ranges from config file
[  1142.223] (II) modeset(0): Using vrefresh ranges from config file
[  1142.223] (II) modeset(0): Printing DDC gathered Modelines:
[  1142.223] (II) modeset(0): Modeline "1920x1080"x0.0  148.50  1920 2008
2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
[  1142.223] (II) modeset(0): Modeline "1920x1080"x0.0  148.50  1920 2448
2492 2640  1080 1084 1089 1125 +hsync +vsync (56.2 kHz e)

Let me know if you spot anything weird, and if you have any suggestions?

thank you!

 - Joel