We found another bug after the fix of https://gitlab.freedesktop.org/drm/intel/-/issues/2538. The external monitor is also connected via WD19's HDMI/DisplayPort just as #2538. However, the display monitor can only be detected and show output at the very first time we power on the WD19 dock. If we unplug the cable and replug again, the monitor seems to be detected but there's no video output.
When we power on the WD19 dock with cable connected to the monitor, the drm kernel log shows as follows
i915 0000:00:02.0: [drm:intel_get_hpd_pins.isra.0 [i915]] hotplug event received, stat 0x00010000, dig 0x0088888a, pins 0x00000200, long 0x00000200 i915 0000:00:02.0: [drm:intel_hpd_irq_handler [i915]] digital hpd on [ENCODER:292:DDI D] - long i915 0000:00:02.0: [drm:intel_hpd_irq_handler [i915]] Received HPD interrupt on PIN 9 - cnt: 10 i915 0000:00:02.0: [drm:intel_dp_hpd_pulse [i915]] got hpd irq on [ENCODER:292:DDI D] - long i915 0000:00:02.0: [drm:i915_hotplug_work_func [i915]] running encoder hotplug functions i915 0000:00:02.0: [drm:i915_hotplug_work_func [i915]] Connector DP-1 (pin 9) received hotplug event. (retry 0) i915 0000:00:02.0: [drm:intel_dp_detect [i915]] [CONNECTOR:293:DP-1] i915 0000:00:02.0: [drm:intel_power_well_enable [i915]] enabling TC cold off i915 0000:00:02.0: [drm:tgl_tc_cold_request [i915]] TC cold block succeeded i915 0000:00:02.0: [drm:__intel_tc_port_lock [i915]] Port D/TC#1: TC port mode reset (tbt-alt -> dp-alt) i915 0000:00:02.0: [drm:intel_power_well_enable [i915]] enabling AUX D TC1 i915 0000:00:02.0: [drm:drm_dp_dpcd_read [drm_kms_helper]] AUX D/port D: 0xf0000 AUX -> (ret= 8) 14 1e 40 55 02 00 00 00 i915 0000:00:02.0: [drm:intel_dp_lttpr_init [i915]] LTTPR common capabilities: 14 1e 40 55 02 00 00 00
Then I replug the cable, the intel_power_well_enable() in intel_dp_aux_xfer() shows "enabling DC off" power domain instead of enabling AUX D TC1. After that, the flooded i915 0000:00:02.0: [drm:intel_dp_aux_xfer [i915]] AUX D/port D: timeout (status 0x7d4003ff) keeps show up and no video output.
I filed a bug on https://gitlab.freedesktop.org/drm/intel/-/issues/3407 and also uploaded the journal log with kernel boot parameter "drm.debug=0x10e".
Can anyone suggest what happens at the replug? What can we do to identify the cause? Thanks
Chris