On 3/14/26 9:51 PM, Val Packett wrote:
On 3/13/26 10:09 PM, Dmitry Baryshkov wrote:
Currently, all HPD interrupt handling must go through the HPD state
machine.
This has caused many issues where the DRM framework assumes that DP is
in one state while the state machine is stuck in another state.
As discussed here [1], this series:
- Removes the state machine
- Moves link training to atomic_enable()
- Changes the detect() behavior to return true if a display is
physically
plugged in (as opposed to if the DP link is ready).
- Remove event queue and move internal HPD handling to hpd_notify()
To correctly detect the displays which are plugged on boot on the boards
which use dp-connector devices, this series depends on [2]. USB-C and
eDP panels are handled natively.
[1]
https://patchwork.freedesktop.org/patch/656312/?series=142010&rev=2#comment_1201738
[2]
https://lore.kernel.org/all/[email protected]/
Unfortunately this currently seems to mostly break link training with
USB-C, on x1e80100-dell-latitude-7455:
[ 102.190083] [drm:msm_dp_ctrl_link_train_1_2 [msm]] *ERROR* link
training #2 on phy 1 failed. ret=-110
[ 102.192846] [drm:msm_dp_ctrl_setup_main_link [msm]] *ERROR* link
training of LTTPR(s) failed. ret=-110
[ 102.211095] [drm:msm_dp_bridge_atomic_enable [msm]] *ERROR* Failed
link training (rc=-104)
[ 102.211164] [drm:msm_dp_aux_isr [msm]] *ERROR* Unexpected DP AUX
IRQ 0x01000000 when not busy
[ 102.247168] [drm:msm_dp_ctrl_link_train_1_2 [msm]] *ERROR* link
training #2 on phy 1 failed. ret=-110
[ 102.252859] [drm:msm_dp_ctrl_setup_main_link [msm]] *ERROR* link
training of LTTPR(s) failed. ret=-110
[..]
Actually looks like that might've been due to having applied the [2]
dp-connector series from above.
Removed it and rebooted, now plugging and unplugging multiple times
between the 2 ports works fine.
Except unplug is still not reliable, the "ghost" monitor often remains
after unplugging.
Almost nothing is logged to dmesg, literally I've only seen this line once:
[drm:msm_dp_panel_read_sink_caps [msm]] *ERROR* panel edid read failed
But I have unplugged the monitor now and I still see:
crtc[108]: crtc-1
enable=1
active=1
self_refresh_active=0
planes_changed=1
mode_changed=0
active_changed=0
connectors_changed=0
color_mgmt_changed=0
plane_mask=2
connector_mask=2
encoder_mask=2
mode: "3840x2560": 60 631750 3840 3888 3920 4000 2560 2563 2573
2633 0x48 0x9
lm[0]=2
ctl[0]=1
lm[1]=3
ctl[1]=1
connector[38]: DP-2
crtc=crtc-1
[..]
and the compositor thinks it's still present, I can move the mouse to
where the screen was etc.
~val
