[Xen-devel] S3 causing IRQ delivery mismatch - i915 hotplug storm

[Ben Guthro <ben@xxxxxxxxxx>]

I'm trying to debug an issue on an older lapop (Toshiba Satellite A505) - that has an i3 processor (M330) - and intel graphics.

This is running under Xen-unstable, and a 3.7-rc4 pvops kernel - but can also be reproduced using kernels as old as 3.2.23 - and hypervisors as old as 4.0.4

(I have cross posted here, because I am not yet sure if this is a Xen, pvops, or i915 issue - and would appreciate opinions in sorting it out.)

The symptoms of the problem exhibit themselves by a lagging mouse in X11 after resume, when using the trackpad.

After digging in a bit, the problem seems a bit more insidious - the i915 kworker responsible for hotplug detection (i915_hotplug_work_func) seems to be getting triggered for every PS2 IRQ - every trackpad mouse movement, and keypress triggers tracing (with drm.debug=0x06) like the following:

Nov 6 21:41:58 rusting kernel: [ 263.924454] [drm:i915_hotplug_work_func], running encoder hotplug functions 

Nov 6 21:41:58 rusting kernel: [ 263.924468] [drm:intel_ironlake_crt_detect_hotplug], ironlake hotplug adpa=0xf40018, result 0 

Nov 6 21:41:58 rusting kernel: [ 263.924472] [drm:intel_crt_detect], CRT not detected via hotplug 

Nov 6 21:41:58 rusting kernel: [ 263.924475] [drm:output_poll_execute], [CONNECTOR:11:VGA-1] status updated from 2 to 2 

Nov 6 21:41:58 rusting kernel: [ 263.926771] [drm:drm_do_probe_ddc_edid], drm: skipping non-existent adapter i915 gmbus dpc 

Nov 6 21:41:58 rusting kernel: [ 263.926775] [drm:output_poll_execute], [CONNECTOR:14:HDMI-A-1] status updated from 2 to 2 

Nov 6 21:41:58 rusting kernel: [ 263.927291] [drm:intel_dp_aux_ch], dp_aux_ch timeout status 0x5145003e 

Nov 6 21:41:58 rusting kernel: [ 263.944207] [drm:intel_dp_aux_ch], dp_aux_ch timeout status 0x5145003e 

Nov 6 21:41:58 rusting kernel: [ 263.964201] [drm:intel_dp_aux_ch], dp_aux_ch timeout status 0x5145003e 

Nov 6 21:41:58 rusting kernel: [ 263.983694] [drm:intel_dp_detect], DPCD: 0000000000000000 

Nov 6 21:41:58 rusting kernel: [ 263.983704] [drm:output_poll_execute], [CONNECTOR:17:DP-1] status updated from 2 to 2

Additionally, this same trace stack is printed out at a regular 10s interval, after resume - where prior to resuming from S3 it is printed out once at boot time.

This kworker consumes a significant portion of the cpu, and essentially grinds Xorg to a halt, until the probing can catch up with the user moving the cursor.

There seems to be a mismatch for these IRQ delivery - or at least exhibits the behavior similar to such a problem.

Does anyone have any thoughts as to where in the software stack I should start to dig in?

Any opinions on which component likely contains the issue is appreciated.

/btg

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel